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1
Thobatsi, Jacob Thobatsi. "Growth and yield responses of maize (Zea mays L.) and cowpea (Vigna unguiculata L.) in an intercropping system." Diss., Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-10122009-184005.
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Harena, Tchamse. "Essai de validation et perspectives d'application en agrometeorologie d'un modele de simulation de la croissance et du developpement du mais : ceres-maize." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF2D214.
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Apres une description du modele couple de simulation du bilan hydrique, du developpement et de la croissance, les valeurs simulees sont comparees aux donnees recueillies lors de quatre annees d'experimentation dans le puy-de-dome sur deux varietes de mais (dea et boree). On a constate que du point de vue phenologique le modele presente un retard de precocite et que les valeurs de croissance sont sous estimees. On etudie la sensibilite du modele aux parametres genetiques d'entree et a deux coefficients numeriques (phyllochrone et plastochrone), puis a la variation de l'etat hydrique du sol et a une irrigation intervenant pendant la floraison femelle
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Maende, Cleophas Makokha. "An application of a model of maize growth to maize production by smallholders in Kenya." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240744.
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Drost, Roelof Gerrit. "MAIS, a mechanistic model of maize growth and development." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61892.pdf.
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Schortemeyer, Marcus. "Effects of nitrogen form on the growth of maize seedlings /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10739.
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Massignam, Angelo Mendes. "Quantifying nitrogen effects on crop growth processes in maize and sunflower /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17639.pdf.
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Verheul, Michel J. "Seedling growth of maize (<> L.) genotypes under chilling conditions /." [S.l.] : [s.n.], 1992. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9855.
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Anil, Leena. "The growth and utilization of forage maize intercrops for livestock production." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266795.
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Olsson, Adam. "Graphene Growth through Chemical Vapor Deposition - Optimization of Growth and Transfer Parameters." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-137546.
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The goal of this thesis work is to investigate the possibility to grow graphene by Chemical Vapor Deposition (CVD) on copper foil with acetylene as a precursor and varigon (5\% H$_2$ in Ar) as a carrier gas. The possibility of nitrogen doping by ammonia treatment during the growth process is also investigated. The possibility of graphene transfer, with the use of Poly(Methyl Metacrylate) (PMMA), from the copper onto another target substrate, Flourine doped Tin Oxide (FTO), is also explored. The main technique of characterization of the grown and transfered graphene is Raman spectroscopy, a great tool for investigating the number of graphene layers and amount of defects. Other characterization methods used are Scanning Electron Microscopy (SEM) X-ray Photoelectron Spectroscopy (XPS) to investigate morphology and elemental composition, respectively. The result of this thesis study is that graphene growth is entirely possible with acetylene as a precursor, as shown by the Raman spectroscopy, XPS and SEM. The grown graphene has a high quality with few layers and a low number of defects. The ammonia treatment, however, doesn't seem to have an immediate effect on the graphene growth. The XPS data indicates that there are no nitrogen doping in the graphene, though there might be a correlation between the ammonia and the number of layers, but further investigations has to be made. Transfer is also proven possible with the method developed. However, improvements to the transfer method can be done since there are both larger tares, caused by the transfer onto the FTO, as well as microscopic tares, possibly caused by thermal expansion of the PMMA.
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Siqueira, Rafael Telles Tenorio de. "Characterizing nitrogen deficiency of maize at early growth stages using fluorescence measurements." Thesis, Colorado State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10138898.
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<p> Among all nutrients that are important for crop production, nitrogen (N) is one of the least efficiently utilized, mainly due to its high mobility in soil. The possibility of using crop sensing in real-time to detect variability in N deficiency within a field has the potential to enhance N efficiency, increase crop yield, and reduce potential environmental risks and crop production costs. Potassium (K), another important crop nutrient, can also lead to higher yield when applied in the right amount and manner. Real-time fluoro-sensing is a new technology for crop sensing and studies have shown that it could enable variable rate nutrient management for precision agriculture practices. The objective of this study was (1) to evaluate if fluorescence sensing can detect variability of N and K in crop canopy at early growth stages of maize (prior to V6 crop growth stage) under controlled condition (greenhouse), (2) to evaluate the effect of different fertilization dosages of N over the plant growth, and (3) to verify if induced fluorescence can detect <i>in situ </i> N variability at early growth stages of maize. Research was conducted in two stages, first in a greenhouse condition and later in field spread over three site-years. The greenhouse research was conduct in year 2011 and plants were grown in plant-pots with silica sand and supplied with modified Hoagland solution with different rates of N and K. Field trials were conducted in year 2012 and 2013 in northern Colorado. For the greenhouse study, data collected via fluorescence sensor (Multiplex<sup>®</sup>3) were analyzed using ANOVA and Tukey’s HSD to test significant differences among treatments in each experiment. For the N experiment, regression analysis between the seven fluorescence indices and N uptake was performed for the 12 days of data acquisition at five different growth stages (i.e. 2-leaf to 6-leaf growth stages) and coefficient of determination was used to identify the best fluorescence indices to detect N status. Also, root mean square error (RMSE) was used to test the precision of the estimates for each index. Results of this study indicated that all fluorescence indices were able to detect N variability in maize canopy prior to V2 growth stage. However, the fluorescence indices failed to identify K deficiency as the maize plants with K treatments showed small variability at early crop growth stages. For the field study, two site-years had 5 N rate treatments applied as UAN 32% (urea ammonium nitrate; 32-0-0), while one site-year had 6 N treatments applied pre-planting. Sensors used in this study were the Multiplex<sup>®</sup>3 for fluorescence sensing and the GreenSeeker<sup>®</sup> for reflectance sensing (NDVI). Sensor measurements were correlated with aboveground biomass, N content, and N uptake measured at two growth stages (V6 and V9 maize growth stage). The aboveground biomass, N content, N uptake, yield, and sensors readings were analyzed using ANOVA and Tukey’s HSD to test significant differences among the N treatments. Also, a regression tree between N uptake and the fluorescence indices was fitted along with the coefficient of determination (R<sup>2 </sup>). The N rates had no effect on aboveground biomass, N content and N uptake (for both sampled growth stages). Under field conditions, fluorescence indices failed to detect N variability in maize at early growth stages for all three site-years. This finding may require further investigation, as for most of the N treatment plots, maize plants had sufficient N levels and another biotic or abiotic stress may be responsible for unexplained differences in N variability as measured by fluorescence sensor. Contrasting findings under greenhouse conditions versus field conditions limit the application of fluorosensing sensor. Further field studies are needed to evaluate the potential of this sensor for detecting N variability <i>in situ.</i></p>
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Yang, Rick L. "Tissue specificity of signal transmission and differential growth during maize root gravitropism." Connect to resource, 1992. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1244222463.
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Raymond, Fred Douglas. "Reducing Corn Yield Variability and Enhancing Yield Increases Through the Use of Corn-Specific Growth Models." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/36304.
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Crop simulation models (CSMs) are used to evaluate management and environmental scenarios on crop growth and yields. Two corn (Zea Mays L.) crop growth simulation models, Hybrid-Maize, and CERES-Maize were calibrated and validated under Virginia conditions with the goal of better understanding corn response to variable environmental conditions and decreasing temporal yield variation. Calibration data were generated from small plot studies conducted at five site-years. Main plots were plant density (4.9, 6.2, 7.4, and 8.6 plants m-2); subplots were hybrids of differing relative maturity (RM) [early = Pioneer® Brand â 34B97â (108 day RM); medium = Pioneer® Brand â 33M54â (114 day RM); and late = Pioneer® Brand â 31G66â (118 day RM)]. Model validation was generated from large scale, replicated strip plot trials conducted at various locations across Virginia in 2005 and 2006. Prior to model adjustments based on calibration data, both CSMs under predicted corn grain yield in calibration and validation studies. CERES-Maize grain yield prediction error was consistent across the range of tested plant density while accuracy of Hybrid-Maize varied with plant density. Hybrid-Maize-estimated biomass production was highly accurate. Greater leaf area index (LAI) and biomass production were measured than was predicted by the CERES-Maize CSM. Both CSMs were modified based on calibration data sets and validated. Validation results of the calibrated CSMs showed improved accuracy in simulating planting date and environmental effects on a range of corn hybrids grown throughout Virginia over two years. We expect that both modified models can be used for strategic research and management decisions in mid-Atlantic corn production.<br>Master of Science
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Traynor, Mary. "Root growth in drying soil : a role for ABA?" Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322894.
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Bond, Jeffery. "The optimization of carbon nanotube growth parameters for photonics." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27447.
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Suspended carbon nanotubes are of particular interest for optical and optoelectronic applications because of their superior optical properties. The purpose of this work is to explore sample preparation and chemical vapour deposition (CVD) process parameters to develop methods of fabricating large quantities of freely suspended single walled carbon nanotubes (SWNTs). Parameters including CVD hydrogen soak temperature, growth temperature, choice of catalyst, gas flow rate, and gas composition were examined.
Various techniques were tested for their practical capability to suspend SWNTs. A simple procedure was used to suspend SWNTs over networks of randomly organized thick MWNTs on unpatterned substrates. In a more versatile procedure SWNTs were suspended between adjacent pillars of vertically aligned MWNT forests on patterned substrates. Large quantities of SWNTs were also suspended over pre-fabricated trenches in the substrate. All of these laterally suspended SWNT were found to be useful for optical studies.
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Boggess, Chadwick D. "Optimization of Growth Parameters for Algal Regrowth Potential Experiments." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1234.
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Water cost is one of the key deterrents in making algal biofuels a feasible alternative to traditional petroleum fuels. Research into recycling of algal media was conducted in a laboratory setting at the California Polytechnic State University in San Luis Obispo. A growth assay was created to allow for algal cultures, specifically Ward’s Chlorella sp., to proliferate in sealed culture vessels. Bold’s Basal Medium (BBM) was selected as the media due to its extensive use with freshwater algal strains. However, this medium can limit algal growth through nutrient limitation and it became necessary to augment the original recipe. 50mM of sodium bicarbonate was added to the media in order to buffer the purging of 100% CO2 into the culture vessel. The resultant pH of the CO2 saturated media was 6.25. The elemental? composition of Chlorella vulgaris was compared with the nutrient content of BBM to estimate possible nutrient limitations which could occur throughout growth (Oh Hama, 1988). From this analysis, the nitrogen and phosphorus concentration in BBM was augmented by a factor of three (BBM3N3P). Further, vitamins, specifically cyanocobalamin, thiamine HCL, and biotin, were incorporated after conducting a comparison growth study with BBM 3N3P. The average maximum specific growth rates for the normal BBM and for the vitamin-enhanced BBM were 0.689 +/- 0.0818 and 0.887 +/- 0.1901 (mean +/- std. deviation) per day, respectively. This difference was proved significant by a t-test with a p-value equal to 0.041. A standardized methodology for conducting a regrowth potential experiment was outlined by the research. One phase of this methodology included reintroduction of nutrients consumed during the first round of growth. Prior to continuing with this methodology the effect of supplementing trace metals and micronutrients into the culture was investigated. At a p-value of 0.0956, there was no significant difference between BBM 3N3P + vitamins and the same media with eight times the trace metal and micronutrient concentration. This allowed for up to seven rounds of regrowth with no inhibition caused from the restoration of these nutrients. A final regrowth was conducted on BBM 3N3P + vitamins + 50 mM bicarbonate. A significant difference existed between both the Round 1 and Round 2 cultures, as well as between the Round 2 cultures and their respective controls. This signified the possible release of allelochemicals by the Chlorella sp.. A preliminary investigation into the possible use of anaerobic digester effluent as a primary source of nutrients for algal cultures was also conducted. The digestate (diluted 50% v/v with a saline make-up) grew significantly faster than the controls (p-value<0.001). Further, after the introduction of trace metals and micronutrients the digestate columns outlived the control columns increasing the feasibility of using digestate to supplemental algal cultures.
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Hugo, Elbé. "Growth responses, competitiveness and control of Digitaria nuda (Schumach.) in maize (Zea mays)." Thesis, University of Pretoria, 2014. http://hdl.handle.net/2263/43354.
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Digitaria species infestation levels have recently increased in South Africa due to the
prevailing misconception amongst producers and herbicide agents that acetanilide
herbicides will control all Digitaria spp. equally effective, irrespective of species differences.
Since 2008 a relatively unknown Digitaria spp was noticed in maize fields and was positively
identified as D. nuda (naked crabgrass). Research on naked crabgrass world-wide is limited;
it has been reported to be of importance in sugarcane in Brazil and is considered as a
serious grass weed in West Africa. Growth chamber trials were conducted to elucidate the
germination characteristics of naked crabgrass. Germination of fresh naked crabgrass seed
was less than 20%. Pre-treatment of fresh seed, by means of soaking seed for 24 h in
distilled water, increased germination to 99%. Stored seed (1-yr old) germinated best (100%)
in a 0.2 M KNO3 solution. Naked crabgrass germinated best at constant temperature greater
than 25 °C and at fluctuating regimens of 30/15 °C, with alternating light/dark conditions.
Naked crabgrass emerged faster and total seedling emergence was 20% higher on clay soil.
Above-ground biomass was 5.0 g per plant on clay soil compared to 2.3 g on sandy soil.
Seedling emergence was reduced by 27% after burial at a depth of 1 cm and only 5% seeds
emerged at a depth of 6 cm. In a replacement series glasshouse trial naked crabgrass was
more aggressive with regard to root mass (AI=0.3) and large crabgrass (D. sanguinalis) with
regard to shoot mass (AI=0.04). Naked crabgrass was more competitive in a wet soil profile
(CR=1.88) and large crabgrass in a dry soil profile (CR=2.02). Both grass weeds are making
similar demands on the available resources (RYT=1). The competition effect of both naked
and large crabgrass was determined in glasshouse trials in two soil types at different
watering regimens. A negative linear relationship was recorded between grass density and
maize plant height, shoot- and kernel weight. Estimated yield loss of maize varied between
29 and 76% and was described by the hyperbolic equation of Cousens (1985). Large
crabgrass had a higher damage coefficient (4.1 on sandy soil) compared to naked crabgrass
(3.1 on clay soil). A critical period of weed control was established in field trials for naked crabgrass. The beginning of the critical period of weed control when a 10% yield loss is
estimated varied between the two and six leaf stage of maize, ending at the twelve leaf
stage or two weeks after tasseling, indicating a need for season-long control of naked
crabgrass. Yield loss of maize in the field trials ranged between 28 and 82% in the seasonlong
weedy control treatments. In field and glasshouse trials the efficacy of naked crabgrass
control was evaluated with different herbicides registered on maize. Naked crabgrass is
more tolerant to acetochlor and s-metolachlor and started to emerge two weeks after
applications. Large crabgrass is still effectively controlled by these herbicides. More than
85% of naked crabgrass was controlled when PRE applications of acetanilide herbicides
were followed by triketone herbicides. Indiscriminate identification of all crabgrass species as
“large crabgrass” can cause a shift from large crabgrass to naked crabgrass since the latter
is more difficult to control. Extrapolation of characteristics and factors affecting germination
and growth between similar species is perilous and should be verified. Results of this study
proved that both grass weeds are severe competitors of maize, causing significant yield
losses, but species specific characteristics could be distinguished and will improve decision
making processes significantly to control naked crabgrass effectively in maize.<br>Thesis (PhD)--University of Pretoria, 2014.<br>lk2014<br>Plant Production and Soil Science<br>PhD<br>Unrestricted
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BEN, HASSINE MORTADHA. "GROWTH, NITROGEN UPTAKE AND MAIZE NITROGEN RECOVERY OF COVER CROPS IN CONSERVATION AGRICULTURE." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/702471.
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Planting winter cover crops has several benefits compared to keeping the soil bare. The choice of the cover crop species and sowing date is crucial to have the best cover crops establishment and weed suppression. The seeds germination of cover crops is affected by the sowing date with a preference of early sowing. However, the appropriate date of cover crops sowing is not known. Also, cover crops nitrogen dynamics is variable among species. In a conservation agriculture context, we conducted two field experiments in Northern Italy and one laboratory experiment under controlled conditions of temperature and soil moisture. The objectives were to (i) assess the growth and nitrogen uptake of five pure winter cover crops (black oat, Avena strigosa Schreb.; cereal rye, Secale cereale. L.; white mustard, Sinapis alba L.; Egyptian clover Trifolium alexandrinum L.; and hairy vetch, Viccia villosa Roth) as influenced by plant species from three botanical families and two sowing dates (SD1 and SD2), (ii) assess the effect of cover crops presence/absence (bare soil) on weed suppression and maize productivity, (iii) estimate and assess the cover crops contribution to the following main crop (maize) in terms of nitrogen recovery and immediate availability, (iv) establish the course of nitrogen mineralization from pure cover crops in laboratory incubation conditions and (v) assess the effect of three managements of winter-hardy cover crops termination methods and control of weed in maize (chemical vs. mechanical) on maize productivity. The field experiments were carried out in Orzinuovi, Brescia, Italy. Relevant differences in cover crops growth were observed among species, with white mustard SD1 having the highest biomass in November (5.3 and 3.2 t ha-1, respectively for the first and the second year) and Egyptian clover the lowest (less than 1 t ha-1). Also, we demonstrated that hairy vetch SD1 had the highest nitrogen uptake in November (114 kg N ha-1). The presence of cover crops reduced weed infestation compared to a bare soil. Sowing cover crops at end of August, instead of mid-September, had a positive effect on production, establishment, nitrogen uptake, and weed suppression. Maize yield following cover crops was not affected by the cover crop sowing dates and species during the two years of experiment. The maize nitrogen recovery was variable within years; the highest recovery was for maize following hairy vetch SD2 (+67%). The importance of sowing cover crops was demonstrated by the higher nitrogen recovery of maize following cover crops compared to maize following no cover crop treatment. In a laboratory incubation experiment of 84 days, cover crop shoots were collected from cover crops grown in the field, mixed with soil and kept under controlled temperature of 20 °C and soil moisture of 100% field capacity. We demonstrated differences in nitrogen mineralization among the five pure cover crops and weed shoots with hairy vetch, collected in March (C/N ratio of 10.1), having the highest and immediate net nitrogen mineralization from the beginning of incubation until 84 days after start of incubation. Black oat collected in March (C/N ratio of 19.8), had also an immediate net nitrogen mineralization during the whole incubation period but at a lower rate compared to hairy vetch. Egyptian clover collected in November (C/N ratio of 11.4), started nitrogen mineralization 7 days after start of incubation. White mustard collected in November (C/N ratio of 17.7), had a low rate of nitrogen mineralization. Shoots of weed, cereal rye, white mustard and black oat collected in March immobilized nitrogen during the whole incubation period at different rates; cereal rye had the highest rate of immobilization and was not able to start nitrogen mineralization 84 days after start of incubation. In the second field experiment our results indicated that a “post-glyphosate” scenario (mechanical termination of cover crops and chemical control of weed in maize) is the best management to produce the highest yield of maize compared to a “business-as-usual” management (chemical termination of cover crops and weed control in maize) and “organic” management (mechanical termination of cover crops and weed control in maize).
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FIGUEIREDO, ANACLETO M. de. "Texture and growth parameters in semisolid processing of Basub2YCusub3Osub7-gamma." reponame:Repositório Institucional do IPEN, 1993. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10345.
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04860.pdf: 16120223 bytes, checksum: e94349c100b463afba7f046b474fbb09 (MD5)<br>Tese (Doutoramento)<br>IPEN/T<br>Massachusetts Institute of Technology - Cambridge, Mass - MIT
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Mkentane, Kwezikazi. "Human scalp hair: geometry, biochemistry, growth parameters and mechanical characteristics." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/23419.
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Scalp hair is increasingly being used as a testing substrate for toxins and monitoring treatment adherence. The biochemistry of human hair is assumed to be similar; however, a recent study reported higher concentration of lipids in African hair. The effect of hair curvature, if any, on drug incorporation (e.g. lipid soluble drugs) is unknown. Racial description of hair morphology is unscientific. A geometric classification of hair into 8 groups (I-straight to VIII-tightly curly) was recently proposed, however its reliability has not been confirmed. The aim of this thesis was to investigate the reliability of the geometric classification (and to assess whether it could be improved) and investigate relationships between morphology and other hair characteristics. Virgin hair was collected from 128 volunteers using a standardized protocol. Geometric measurements of hair using published templates were conducted for classification. Reliability was assessed using Kappa statistics. Characteristics assessed included mechanical properties (miniature tensile tester), growth rate and hair density (TrichoScan® trichogram), biochemistry (Vanillin assay for lipids and Fourier Transform Infrared adsorption) and imaging (Electron and Fluorescent Light Microscopy). Inter-observer agreement was poor for 8-groups (k=0.418) but improved for 6-groups (k=0.671). The intra-observer agreement also improved [ranges: k=0.444 to 0.648 (8-groups) and k=0.599 to 0.836 (6-groups)]. The yield strength of all hair groups was higher than reported for racially grouped samples. Curly hair groups had lower growth rates and tensile strengths. The TrichoScan based growth rate was for fastest for the straightest (0.72±0.3 cm/month) and slowest for the curliest (0.39 ± 0.2 cm/month) hair. No correlation with biochemistry was detected for either the 8 or 6-group classification, although a trend toward higher absorption of lipid (C-H) bands was noted for curly hair. A supervised statistical approach applied to 4 hair groups using the FTIR data improved classification success to 79% (range: 69% - 88%), which needs confirmation but would be more objective than using race for hair testing in Medicine and Forensic Science. This thesis supports a geometric classification with fewer groups (6, based kappa statistics and 4, based on biochemistry); it is also the first to report correlations between hair geometry, biochemistry and physical properties.
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Gurney, Anita L. "Growth and photosynthetic responses of maize and sorghum to the parasitic weed Striga hermonthica." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267174.
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Cho, In-jeong. "Function of abscisic acid in maintenance of maize primary root growth under water deficit." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4459.
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Thesis (Ph.D.)--University of Missouri-Columbia, 2006.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file plus two media files. Title from title screen of research.pdf file (viewed on May 1, 2009) Vita. Includes bibliographical references.
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Macharia, J. N. M. "Growth and photosynthesis of maize (Zea mays L.) in sub-optimal environments with particular reference to Britain and Kenya." Thesis, University of Essex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234197.
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Njaimwe, Arnold Ngare. "Tillage and crop rotation impacts on soil, quality parameters and maize yield in Zanyokwe Irrigation Scheme, South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/460.
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Intensive tillage and monoculture cropping practices reduce soil C accumulation hence increasing soil vulnerability to chemical, physical and biological degradation. This study focussed on enhancing biomass production of wheat and oat winter cover crops as a means of increasing C sequestration in the low organic C soils of the central part of Eastern Cape Province. The specific objectives were (i) to evaluate the short-term effects of no till and cereal-fallow based crop rotations on; soil organic matter related parameters, pH and electrical conductivity, (ii) soil bulk density, water retention and aggregate stability, (iii) soil microbial biomass C and N, mineralizable N, soil respiration, and dehydrogenase enzyme activity, (iv) grain yield, soil nutrient concentration (N, P and K) and their uptake by maize, and (v) to identify soil parameters with high sensitivity to tillage under maize-fallow-maize, maize-wheat-maize and maize-oat-maize rotational cover cropping practices. The experiment was laid out as a split-plot arrangement in a randomized complete block design with 4 replicates. Tillage treatments (CT and NT) were applied on the main plots which measured 8 × 18 m while crop rotation treatments were applied in the subplots which measured 8 × 6 m. The rotation treatments were maize-fallow-maize (MFM), maize-wheat-maize (MWM) and maize-oat-maize (MOM). Weed control in NT plots involved preplant application of glyphosate to control mainly the grass weeds while post emergence weed management was done using Atrazine (485 atrazine and 15 g l-1 triazines). Initial weed control in CT plots was achieved through ploughing to a depth of 20 cm followed by disking while post emergence weed iii management was done by hand hoeing. Soil parameters measured were; (i) particulate organic matter (POM), soil organic carbon (SOC), total nitrogen (TN), pH and electrical conductivity (EC), (ii) soil bulk density (b), moisture at field capacity (FC), aggregate mean weight diameter (MWD) determined by fast wetting (FW), slow wetting (SW), mechanical breakdown by shaking (MB) and the stability index (SI), (iii) soil microbial biomass C (MBC) and N (MBN), mineralizable N (MN), soil respiration (SR), and dehydrogenase enzyme activity (DHEA). No-till increased POM and TN compared to CT in Lenye and Burnshill, respectively. The MWM and the MOM rotations increased TN relative to the MFM rotation in Lenye. The MWM and MOM rotations enhanced SOC relative to MFM in all sampled soil depths at Burnshill and similar observations were made under MOM rotation in the 5-20 cm depth in Lenye. The MWM and MOM rotations tended to depress soil pH relative to the MFM rotation in both sampled soil depths in Lenye while NT reduced soil pH relative to CT on the surface soil layer in Burnshill. Soil EC and pH varied with depth across tillage practices but both parameters remained within the ideal range for successful crop production over the study period. Soil stability index (SI) and aggregate MWD determined by FW, SW and MB were higher in Lenye compared to Burnshill. The MOM rotation enhanced the SI relative to MFM and MWM rotations at both sites. Scanning electron microscope (SEM) showed that more organic C was incorporated into the soil under NT and MOM rotation compared to CT and MFM rotation which had few organic coatings on the soil particles. Microbial properties varied with plant biomass input as influenced by tillage and type of rotational cover crop at both sites. Like in other past studies, NT showed higher levels of MBC, MBN, NM and SR at the soil surface layer compared to CT in Burnshill. No till increased MN iv relative to CT in both sampled soil depths in Lenye and resulted in higher DHEA compared to CT in Burnshill. The MOM rotation increased MBC, MBN, MN relative to MFM rotation especially within surface soil layer. Similar observations were made with respect to MN and SR in both sampled soil layers at Lenye. By contrast, the DHEA was higher under the MFM relative to the MWM and MOM rotations in Lenye but similar under the MFM and MOM rotations in Burnshill. Maize grain yield was not affected by both tillage and crop rotations but varied with cropping season. Comparable grain yields observed under the two tillage practices with similar fertilizer application rates indicated the advantage of NT over CT in saving on labour costs in maize production without compromising yields. High plant biomass retention under NT relative to CT contributed to high soil N and P levels under the former compared to the latter tillage practice especially on soil surface layer at both study sites. Principal component analysis (PCA) revealed that soil chemical and biological parameters closely linked to organic matter, namely SOC, MN, MBC and MBN showed the highest sensitivity to tillage and crop rotation treatments. Soil aggregate MWD determined by SW and b were the physical parameters which were highly altered by agronomic management practice. The MWM and MOM rotations were clustered together and clearly separated from the MFM rotation and this observed trend only applied to the 0-5 and 5-20 cm depths in Lenye site only. No till, MWM and MOM rotations enhanced POM, SOC and TN relative to CT and MFM rotation suggesting these practices have greater potential to improve soil chemical properties compared to intensive tillage and maize monoculture based production practices. Reduced soil b under MOM rotation and improved SI under NT compared to MFM and CT, respectively v indicate that these practices have the potential to improve degraded soils. Although not significantly different, NT values for MBC, MBN, MN, SR and DHEA were higher compared to CT indicating the potential of the practice to improve soil biotic activity relative to conventional tillage practices. No till enhanced surface soil nitrate N and extractable P compared to CT at both sites revealing the long-term potential of NT in improving the supply of these essential plant nutrients compared to CT. Principal component analysis showed that SOC, MN, K, P, MBC, MBN, soil aggregate MWD determined by SW and b were the most sensitive parameters to tillage and crop rotations. Therefore, these parameters could constitute the minimum data set for assessments of the impact of selected CA practices on soil quality attributes.
24
Ali, Rao Sajjad. "The potential for breeding Zea mays (L.) for saline conditions." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387451.
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Bello, Zaid Adekunle. "Effect of soil nutrient status on growth, reproductive development and yield components of maize in a long term field trial." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/28237.
Full textAbstract:
The research objectives were to examine the effect of soil nutrient status on the growth rate, reproductive development, yield components and yield of maize in a long-term trial. On the Experimental Farm of the University of Pretoria, treatments selected for this investigation were O (control), PK (nitrogen deficient), NK (phosphorus deficient), NP (potassium deficient), NPK (balanced nutrient), and WNPKM (mixture of balanced nutrient and manure). Growth analyses were performed, embryonic tassel and ear development recorded, developmental stages and rate of tasseling and silking were monitored while yield components were determined at maturity. The balanced nutrient treatment (WNPKM) plants showed the highest growth rate and produced the highest biomass while the P and K deficient treatments resulted in low growth rates and low biomass. The PK and NPK treatments were intermediate in terms of growth rate and biomass production. The WNPKM, NPK and PK treatments exhibited a high net assimilation rate (NAR) and crop growth rate (CGR), illustrating that an adequate supply of N, P and K is required for high growth rate and biomass production. Plants in the WNPKM plots exhibited early tassel initiation and ear differentiation and larger reproductive organs. Reproductive development in the PK treatment was ahead of those of the NP and NPK treatments. Nutrient stress delayed initiation and differentiation resulting in smaller reproductive organs. A linear relationship was found between leaf area indices (LAI) and the sizes of the reproductive structures. The higher the LAI the larger the size of the reproductive structures. Emergence of inflorescences was timely in plants exposed to the balanced nutrient but delayed in nutrient deficient treatments. Grain yield and the yield components were positively affected by the balanced nutrient treatment while the nutrient stress treatments reduced the yield. Copyright 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bello, ZA 2008, Effect of soil nutrient status on growth, reproductive development and yield components of maize in a long term field trial, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-02122009-105701 / > E1251/gm<br>Dissertation (MSc(Agric))--University of Pretoria, 2008.<br>Plant Production and Soil Science<br>unrestricted
26
Kruger, Marlene. "An investigation into the development and status of resistance of Busseola fusca (Lepidoptera: Noctuidae) to Bt maize / Marlene Kruger." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4573.
Full textAbstract:
Based on surface area, South Africa is currently ranked 8th in planting genetically
modified (GM) crops in the world. The stem borer, Busseola fusca (Fuller) (Lepidoptera:
Noctuidae) is of economic importance throughout sub–Saharan Africa. Bt maize
(MON810) has been grown to control lepidopterous stem borers in South Africa since its
first release in 1998. The first report of resistance to Bt maize was made in the
Christiana area of South Africa in 2007. The objectives of this study were to evaluate
the status of resistance of populations of B. fusca to Bt maize; to evaluate farmers'
perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and
how the field situation developed between 1998 and 2010; to compare the fitness of the
fertility, fecundity and longevity of Bt–resistant and susceptible B. fusca populations and
to determine if there are fitness costs associated with resistance of B. fusca to Bt maize.
Questionnaire surveys were conducted amongst 185 farmers in seven districts
throughout the maize production region. The questionnaire addressed signing of
contracts upon purchasing GM seed, refuge compliance, pest management practices,
perceived benefits and risks relating to Bt maize. In order to study fitness and fitness
costs that may be associated with resistance development, the life history parameters of
known Bt–resistant and susceptible populations were compared in the laboratory using a
diapauses–as well as second–generation populations collected in maize fields. The
following parameters were compared between different stem borers populations and
treatments: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and
sex ratio. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810)
and that larvae collected from refugia at Vaalharts were resistant and survived on Bt
maize. Compliance to refugia requirements was low especially during the initial 5 – 7
years after release. An alarmingly high number of farmers applied insecticides as
preventative sprays on Bt maize and refugia. Except for moth longevity and LT50–
values, no other fitness costs were observed to be associated with the resistance trait in
the highly resistant B. fusca population used in this study. The LT50 may indicate some
degree of fitness cost but does not translate into observable costs in terms of fecundity,
larval mass and survival. The absence of fitness costs may promote the use of
alternative Bt–resistance management strategies, such as the introduction of a multigene strategy. The introduction of a stacked event such as MON89034 which produces
more than one protein with activity active against the resistant target pest, together with
compliance to the refuge strategy, is most likely the only solution to managing Btresistant
stem borer populations in South Africa.<br>Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.
27
Chao, Sheng. "The Investigation of Growth Parameters and Characterization of Dilute Nitride Semiconductors." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523134.
Full text
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Lindquist, Miles T. "Investigation of growth parameters for as-grown 2D materials- based devices." Ohio University Honors Tutorial College / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1492781232538674.
Full text
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Shonjani, Saeed. "Salt sensitivity of rice, maize, sugar beet, and cotton during germination and early vegetative growth." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965829588.
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Magallón, Servin Paola. "Development of an inoculant of phosphate rock-solubilizing bacteria to improve maize growth and nutrition." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30283/30283.pdf.
Full textAbstract:
L'utilisation directe de roche phosphatée (RP) est une alternative viable pour remplacer les coûteux fertilisants chimiques dans les pays en voie de développement. L'utilisation de bactéries solubilisatrices de RP (BSRP) est un bon moyen pour augmenter la réactivité de la RP. L'objectif principal de ce travail a été d'obtenir des isolats provenant de la mycorhizosphère du maïs possédant une grande capacité de solubilisation de RP, compatibles avec la mycorhize arbusculaire (MA) et présentant des traits associés aux rhizobactéries favorisant la croissance de plantes (RFCP) pour le développement d'un inoculant bactérien pour le maïs.À partir de 118 isolats obtenus de maïs biologique cultivé au Québec, huit BSRP ont été identifiés comme Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 et Sr24) et Pantoea agglomerans (Vr9, Ve16 et Vr25). En milieu liquide, les isolats ont dissous le P des RP selon leur réactivité (Gafsa>Tilemsi>Maroc). La solubilisation des RP s'est effectuée par la production d'acides organiques (OA) et l'abaissement du pH. Les meilleures BSRP de chaque groupe: (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 et P. agglomerans Vr25) ont été sélectionnées selon leur capacité élevée de solubilisation de la RP et de leur production d'acide indolacétique (AIA) et de sidérophores. L’importance des biofilms formés, ainsi que le degré de motilité variaient selon les isolats et tous étaient compatibles avec le Glomus irregulare (Gi). L’étude de la colonisation des racines montre que R. aquatilis Sr24 et P. agglomerans Vr25 ont été les meilleurs colonisateurs. Lors des expériences en serre, certains mélanges contenant R. aquatilis Sr24, P. agglomerans Vr25 et Gi, ont amélioré la biomasse, l'absorption des nutriments et la colonisation de la plante en association avec un champignon mycorhizien indigène du maïs cultivé dans un sol non stérile et fertilisé avec la RP Marocaine. Nous attribuons ces résultats à leur capacité d'être de bonnes BSRP colonisatrices des racines. Elles sont aussi compatibles avec Gi et sont capables de produire de l'AIA et des sidérophores. Cette thèse démontre donc le potentiel d'utilisation de BSRP comme inoculant afin d'améliorer l'efficacité de l'utilisation directe de RP comme fertilisant phosphaté pour l'agriculture durable du maïs.<br>Phosphorous is the second most important nutrient for plant growth, but its availability is often reduced. Therefore high quantities of expensive soluble P-fertilizers are added to soil. Direct use of phosphate rock (PR) is an alternative to chemical P-fertilizers in developing countries and for sustainable agriculture. In order to increase PR reactivity the use of phosphate rock-solubilizing bacteria (PRSB) is a good alternative. Therefore, the main objective of this work was to obtain mycorrhizosphere-competent PRSB presenting other PGPR-associated traits to be used for the development of an inoculant to improve maize growth and P nutrition. Out of 118 isolates obtained from organically grown maize in Quebec, eight PRSB were identified as Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 and Sr24) and Pantoea agglomerans (Vr9, Ve16 and Vr25). All isolates were able to mobilize P from different sparingly soluble P sources in solid media. In liquid medium the isolates were able to solubilize P from PRs according to their reactivity (Gafsa>Tilemsi>Morocco). PRs were solubilized by the production of organic acids (OAs) and by lowering the pH. The best PRSB from each group (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 and P.3 agglomerans Vr25) were selected based on their high PR solubilization, and capacity for indolacetic acid (IAA) and siderophore production. These four isolates presented different biofilm formation and motility capacities and were compatible with Glomus irregulare (Gi). A root colonization study showed that R. aquatilis Sr24 and P. agglomerans Vr25 were the best root colonizers. Vr25 was very competitive when used with other PRSB. In greenhouse trials, plant inoculation with R. aquatilis Sr24 and P. agglomerans Vr25 in addition to Gi, increased the biomass, nutrient uptake in non-sterile soil amended with Moroccan PR (MPR). We attribute these results not only to their PR-solubilizing capacity but also for their ability to be good PRSB, competitive root colonizers, compatible with Gi and to produce IAA and siderophores. This thesis shows that PRSB with AM fungi can be used as inoculants to improve the efficiency of the direct use of PR as P fertilizer for sustainable maize production.
31
Kanton, Roger Adamu Lure. "Growth, yield components and resource use by morphologically contrasting maize-pea sole crops and intercrops." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408994.
Full text
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Magallón-Servin, Paola, and Paola Magallón-Servin. "Development of an inoculant of phosphate rock-solubilizing bacteria to improve maize growth and nutrition." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/24965.
Full textAbstract:
L'utilisation directe de roche phosphatée (RP) est une alternative viable pour remplacer les coûteux fertilisants chimiques dans les pays en voie de développement. L'utilisation de bactéries solubilisatrices de RP (BSRP) est un bon moyen pour augmenter la réactivité de la RP. L'objectif principal de ce travail a été d'obtenir des isolats provenant de la mycorhizosphère du maïs possédant une grande capacité de solubilisation de RP, compatibles avec la mycorhize arbusculaire (MA) et présentant des traits associés aux rhizobactéries favorisant la croissance de plantes (RFCP) pour le développement d'un inoculant bactérien pour le maïs.À partir de 118 isolats obtenus de maïs biologique cultivé au Québec, huit BSRP ont été identifiés comme Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 et Sr24) et Pantoea agglomerans (Vr9, Ve16 et Vr25). En milieu liquide, les isolats ont dissous le P des RP selon leur réactivité (Gafsa> Tilemsi> Maroc). La solubilisation des RP s'est effectuée par la production d'acides organiques (OA) et l'abaissement du pH. Les meilleures BSRP de chaque groupe: (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 et P. agglomerans Vr25) ont été sélectionnées selon leur capacité élevée de solubilisation de la RP et de leur production d'acide indolacétique (AIA) et de sidérophores. L’importance des biofilms formés, ainsi que le degré de motilité variaient selon les isolats et tous étaient compatibles avec le Glomus irregulare (Gi). L’étude de la colonisation des racines montre que R. aquatilis Sr24 et P. agglomerans Vr25 ont été les meilleurs colonisateurs. Lors des expériences en serre, certains mélanges contenant R. aquatilis Sr24, P. agglomerans Vr25 et Gi, ont amélioré la biomasse, l'absorption des nutriments et la colonisation de la plante en association avec un champignon mycorhizien indigène du maïs cultivé dans un sol non stérile et fertilisé avec la RP Marocaine. Nous attribuons ces résultats à leur capacité d'être de bonnes BSRP colonisatrices des racines. Elles sont aussi compatibles avec Gi et sont capables de produire de l'AIA et des sidérophores. Cette thèse démontre donc le potentiel d'utilisation de BSRP comme inoculant afin d'améliorer l'efficacité de l'utilisation directe de RP comme fertilisant phosphaté pour l'agriculture durable du maïs.<br>L'utilisation directe de roche phosphatée (RP) est une alternative viable pour remplacer les coûteux fertilisants chimiques dans les pays en voie de développement. L'utilisation de bactéries solubilisatrices de RP (BSRP) est un bon moyen pour augmenter la réactivité de la RP. L'objectif principal de ce travail a été d'obtenir des isolats provenant de la mycorhizosphère du maïs possédant une grande capacité de solubilisation de RP, compatibles avec la mycorhize arbusculaire (MA) et présentant des traits associés aux rhizobactéries favorisant la croissance de plantes (RFCP) pour le développement d'un inoculant bactérien pour le maïs.À partir de 118 isolats obtenus de maïs biologique cultivé au Québec, huit BSRP ont été identifiés comme Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 et Sr24) et Pantoea agglomerans (Vr9, Ve16 et Vr25). En milieu liquide, les isolats ont dissous le P des RP selon leur réactivité (Gafsa> Tilemsi> Maroc). La solubilisation des RP s'est effectuée par la production d'acides organiques (OA) et l'abaissement du pH. Les meilleures BSRP de chaque groupe: (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 et P. agglomerans Vr25) ont été sélectionnées selon leur capacité élevée de solubilisation de la RP et de leur production d'acide indolacétique (AIA) et de sidérophores. L’importance des biofilms formés, ainsi que le degré de motilité variaient selon les isolats et tous étaient compatibles avec le Glomus irregulare (Gi). L’étude de la colonisation des racines montre que R. aquatilis Sr24 et P. agglomerans Vr25 ont été les meilleurs colonisateurs. Lors des expériences en serre, certains mélanges contenant R. aquatilis Sr24, P. agglomerans Vr25 et Gi, ont amélioré la biomasse, l'absorption des nutriments et la colonisation de la plante en association avec un champignon mycorhizien indigène du maïs cultivé dans un sol non stérile et fertilisé avec la RP Marocaine. Nous attribuons ces résultats à leur capacité d'être de bonnes BSRP colonisatrices des racines. Elles sont aussi compatibles avec Gi et sont capables de produire de l'AIA et des sidérophores. Cette thèse démontre donc le potentiel d'utilisation de BSRP comme inoculant afin d'améliorer l'efficacité de l'utilisation directe de RP comme fertilisant phosphaté pour l'agriculture durable du maïs.<br>Phosphorous is the second most important nutrient for plant growth, but its availability is often reduced. Therefore high quantities of expensive soluble P-fertilizers are added to soil. Direct use of phosphate rock (PR) is an alternative to chemical P-fertilizers in developing countries and for sustainable agriculture. In order to increase PR reactivity the use of phosphate rock-solubilizing bacteria (PRSB) is a good alternative. Therefore, the main objective of this work was to obtain mycorrhizosphere-competent PRSB presenting other PGPR-associated traits to be used for the development of an inoculant to improve maize growth and P nutrition. Out of 118 isolates obtained from organically grown maize in Quebec, eight PRSB were identified as Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 and Sr24) and Pantoea agglomerans (Vr9, Ve16 and Vr25). All isolates were able to mobilize P from different sparingly soluble P sources in solid media. In liquid medium the isolates were able to solubilize P from PRs according to their reactivity (Gafsa> Tilemsi> Morocco). PRs were solubilized by the production of organic acids (OAs) and by lowering the pH. The best PRSB from each group (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 and P.3 agglomerans Vr25) were selected based on their high PR solubilization, and capacity for indolacetic acid (IAA) and siderophore production. These four isolates presented different biofilm formation and motility capacities and were compatible with Glomus irregulare (Gi). A root colonization study showed that R. aquatilis Sr24 and P. agglomerans Vr25 were the best root colonizers. Vr25 was very competitive when used with other PRSB. In greenhouse trials, plant inoculation with R. aquatilis Sr24 and P. agglomerans Vr25 in addition to Gi, increased the biomass, nutrient uptake in non-sterile soil amended with Moroccan PR (MPR). We attribute these results not only to their PR-solubilizing capacity but also for their ability to be good PRSB, competitive root colonizers, compatible with Gi and to produce IAA and siderophores. This thesis shows that PRSB with AM fungi can be used as inoculants to improve the efficiency of the direct use of PR as P fertilizer for sustainable maize production.<br>Phosphorous is the second most important nutrient for plant growth, but its availability is often reduced. Therefore high quantities of expensive soluble P-fertilizers are added to soil. Direct use of phosphate rock (PR) is an alternative to chemical P-fertilizers in developing countries and for sustainable agriculture. In order to increase PR reactivity the use of phosphate rock-solubilizing bacteria (PRSB) is a good alternative. Therefore, the main objective of this work was to obtain mycorrhizosphere-competent PRSB presenting other PGPR-associated traits to be used for the development of an inoculant to improve maize growth and P nutrition. Out of 118 isolates obtained from organically grown maize in Quebec, eight PRSB were identified as Asaia lannaensis Vb1, Pseudomonas sp. Vr14, Rahnella aquatilis (Vr7, Vr13 and Sr24) and Pantoea agglomerans (Vr9, Ve16 and Vr25). All isolates were able to mobilize P from different sparingly soluble P sources in solid media. In liquid medium the isolates were able to solubilize P from PRs according to their reactivity (Gafsa> Tilemsi> Morocco). PRs were solubilized by the production of organic acids (OAs) and by lowering the pH. The best PRSB from each group (A. lannaensis Vb1, Pseudomonas sp. Vr14, R. aquatilis Sr24 and P.3 agglomerans Vr25) were selected based on their high PR solubilization, and capacity for indolacetic acid (IAA) and siderophore production. These four isolates presented different biofilm formation and motility capacities and were compatible with Glomus irregulare (Gi). A root colonization study showed that R. aquatilis Sr24 and P. agglomerans Vr25 were the best root colonizers. Vr25 was very competitive when used with other PRSB. In greenhouse trials, plant inoculation with R. aquatilis Sr24 and P. agglomerans Vr25 in addition to Gi, increased the biomass, nutrient uptake in non-sterile soil amended with Moroccan PR (MPR). We attribute these results not only to their PR-solubilizing capacity but also for their ability to be good PRSB, competitive root colonizers, compatible with Gi and to produce IAA and siderophores. This thesis shows that PRSB with AM fungi can be used as inoculants to improve the efficiency of the direct use of PR as P fertilizer for sustainable maize production.
33
Wu, Yajun. "Cell wall proteins and growth maintenance of the maize primary root at low water potentials /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9720531.
Full text
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Leyendecker, Heinz Bert. "Investigation of design parameters for semi-closed fumigation facilities." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361556.
Full text
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Saropulos, Athanassios S. "Chilling-induced physiological dysfunction in leaves of Zea mays L. and Capsicum annuum L. seedlings." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283693.
Full text
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Makaronidis, Georgios. "Influence of growth parameters on the structural quality of MOCVD grown GaN." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616243.
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Kellerman, Stephanie, and S. J. Schoeman. "The influence of dietary protein levels on growth curve parameters of quail." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/830.
Full textAbstract:
Thesis (MPhil (Agrisciences)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: In South Africa quail do not have the same status as an agricultural produce as do other livestock
species. As quail has mostly been judged as a cute little bird seen on shows, very few people have
paid attention to the commercial value of this bird specie.
In South Africa quail farming is done on a very limited scale, but competition regarding this very
unique market is already challenging. If it is to be a viable project it is of utmost importance to limit
the costs to the minimum and, by doing so, increasing the profitability of the project.
In this study the economic aspects of a quail production unit was researched to assess whether any
improvements in profitability could be made.
Quails from a production unit outside Stellenbosch were used to describe the growth curves of these
birds under three different diet regimes. 300 Birds were used and then divided into groups of a
hundred. The first treatment was fed the standard starter (22% protein) then after five weeks a
finisher (19% protein). The second treatment was fed a starter ration containing 40% Soya oil cake
and 60% of the standard starter (27.2% protein). The same finisher as in treatment one was fed to
treatment two after five weeks. Treatment three was fed a newly formulated starter ration (28%
protein). The same finisher was fed to treatment three after five weeks as with the first two
treatments.
It was found that treatments one and two differed significantly from treatment three, but not from
each other. It was expected that treatment three would result in better growth than treatment one,
but contrariwise, treatment three did the worst. In accordance with literature it was found that under
commercial conditions quail could be fed lower concentrations of protein than prescribed by
literature.<br>AFRIKAANSE OPSOMMING: As 'n landbouproduk het kwartels in Suid-Afrika nie dieselfde status as ander lewende hawe nie.
Omdat kwartels merendeels gesien is as 'n oulike klein voeltjie op skoue, het weinig mense enige
aandag gegee aan die kommersiele waarde van kwartels.
Alhoewel kwartelboerdery in Suid-Afrika huidiglik slegs op 'n baie klein skaal bedryf word, is
kompetisie in hierdie nismark reeds kompeterend en uitdagend. Om so 'n boerdery ekonomies
vatbaar te maak en hoe profyt marges te handhaaf, is dit van wesenlike belang om insetkostes tot
die minimum te beperk.
In hierdie studie is ekonomiese aspekte van 'n kwartel produksie eenheid nagevors om sodoende te
kon bepaal op watter aspekte, indien enige, gekonsentreer kan word om wins marges te verhoog.
Kwartels van 'n produksie eenheid buite Stellenbosch is gebruik. Hierdie kwartels is op drie
verskillende diete geplaas en afsonderlik ge-evalueer om die groeikurwes op elke dieet te bepaal.
Driehonderd kwartels is in groepe van honderd elk verdeel. Die eerste groep se dieet het bestaan uit
die standaard beginners groeimeel wat deur Meadows vervaardig word (22% proteren), en is na vyf
weke afgerond na 'n afrondings dieet (19% proteren). Die tweede groep se dieet was dieselfde
beginners dieet as in groep een wat met 40% Soya oliekoek gemeng is (totale proteren inhoud van
27.2%). Daar is na vyf weke oorgeslaan na dieselfde afrondings dieet as in groep een. Die derde
dieet het bestaan uit 'n nuut geformuleerde beginners dieet (28% proteren). Weereens is daar na vyf
weke oorgeslaan na dieselfde afrondings dieet as in die vorige twee groepe.
Daar is gevind dat die groeikurwes van diete een en twee beduidend verskil het van dieet drie, maar
daar was nie 'n beduidende verskil tussen groepe een en twee nie. Alhoewel daar verwag is dat
dieet drie 'n beter groeikurwe sou toon as dieet een, was dit egter nie die geval nie. Dieet drie het
egter die swakste groeikurwe getoon. Daar is dus gevind dat kwartels onder kommersiele toestande
laer konsentrasies proteren gevoer kan word as wat algemeen voorgeskryf word.
38
Serra-Stepke, Ignacio M. "Influence of soil parameters and canopy structure on root growth and distribution." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4184.
Full textAbstract:
Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: Because of long-term climate changes, apparently associated with higher temperatures and
fewer rainfall events, factors such as water-use efficiency and site selection for new cultivars are
a matter of increasing importance for viticulture. Within this context, the root system is expected
to play a key role. Its relevance to grapevine functioning is due to the numerous functions in
which it is involved. In the light of this, the development of the root system is highly relevant to
the viticulturist because of the fact that grapevine growth and functioning are dependent on the
development of the root system. Differences can, therefore, be expected in terms of berry
ripening on single grapevines of the same scion for situations with differing development of root
systems, despite being grafted on the same rootstock.
Root growth is influenced by several factors, among the ecological aspects. Soil parameters
have a predominant influence on root growth and distribution but also annual root production
can be altered by canopy manipulation. Due to the importance of root growth to the
aboveground development of the vine, it is critical to gain understanding of the relationship
between soil factors and root growth and distribution, and the central role that the subterranean
environment plays in the concept of terroir. This study aimed to investigate the effect of selected
soil physical and chemical parameters on root growth and distribution and to investigate
whether having very different canopies influences root growth. In order to achieve these goals,
two experiments were conducted; the first was performed in two commercial Sauvignon blanc
vineyards each grafted onto Richter 110, non-irrigated, with two treatments: undisturbed lateral
growth and complete lateral removal. The second study included the analysis of eight
commercial Sauvignon blanc vineyards grafted onto Richter 99 and Richter 110 located in the
Stellenbosch Wine of Origin District. Measurements of physical and chemical soil parameters,
root growth and distribution, canopy growth and functioning, vine water status and berry
composition were performed.
The edaphic factors appeared to be one of the most important parameters that affected root
development by changing soil water availability and possibly causing physical or chemical
limitations on root growth. From the results of this study, it is clear that severe water stress and
a pH (KCl) lower than 4.5 play a key role in the limitation of root growth. Due to the fact that
most of the soils from the Stellenbosch Wine of Origin District, especially the subsoils, are
acidic, this is a factor to consider before planting. On the other hand, the combination of
favourable edaphic conditions, such as a subsoil pH of higher than 5.0, light- to mediumtextured
subsoil and moderate water stress, allow increased growth of thin roots.
However, the effect of canopy management on root growth cannot be discounted due to its
importance in the variation of carbohydrate demand by competing sinks. This study showed that
lateral removal done from when the berries are at pea size results in an increase in the number
of thin roots (0.5-2.0 mm). The secondary leaf area represents at least the same leaf area as
the primary leaf area in all the vineyards evaluated, which reveals the relative importance of the
laterals in the total leaf area of the vine and the potential importance in terms of microclimate
and leaf area available for photosynthesis. Studies of root growth should take the vineyard
canopy architecture into account.<br>AFRIKAANSE OPSOMMING: As gevolg van langtermyn klimaatsveranderinge wat toegeskryf kan word aan die voorkoms van
hoër temperature en laer reënval, is faktore soos effektiwiteit van waterverbruik en
liggingseleksie vir nuwe kultivars van kardinale belang vir wingerdkunde. Binne hierdie konteks,
speel die wortelsisteem ‘n belangrike rol. Die belangrikheid hiervan vir wingerdfunksionering kan
toegeskryf word aan die talle funksies waarby dit betrokke is. Die ontwikkeling van die
wortelsisteem is dus hoogs relevant vir die wingerdkundige, omdat wingerdgroei en
funksionering afhanklik is van die ontwikkeling van die wortelsisteem. Verskille kan daarom dus
verwag word in terme van korrelrypwording op ‘n enkele wingerdstok van dieselfde onderstok
vir gevalle met verskillende ontwikkeling van die wortelsisteem, ten spyte daarvan dat dit op
dieselfde onderstok geënt is.
Wortelgroei word, onder ekologiese aspekte, deur verskillende faktore beïnvloed. Grondfaktore
het meerendeels ‘n predominante invloed op wortelgroei en -verspreiding, terwyl jaarlikse
wortelproduksie deur lowermanipulasie beïnvloed kan word. Weens die belangrikheid van
wortelgroei vir die bogrondse ontwikkeling van die wingerd, is dit krities om kennis op te doen
oor die verhouding tussen grondfaktore en wortelgroei en –verspreiding, asook die sentrale rol
wat die subterreinomgewing op die terroir-konsep speel. Die studie was daarop gemik om die
invloed van geselekteerde fisiese en chemiese parameters van grond op wortelgroei en
-verspreiding vas te stel, en ook te ondersoek of verskillende lowers wortelgroei sal beïnvloed.
Om laasgenoemde doelwitte te bereik, is twee eksperimente uitgevoer. Die eerste is uitgevoer
in ‘n kommersïele Sauvignon blanc-wingerd wat geënt is op Richter 110, sonder besproeïng en
met twee behandelings, naamlik onversteurde sêkondere lootgroei en volledige sêkondere
lootverwydering. Die tweede studie het die analise van agt kommersïele Sauvignon blancwingerde
geënt op Richter 99 en Richter 110 in die Stellenbosch Wyn van Oorsprong Distrik.
Metings van fisiese en chemiese grondfaktore, wortelgroei en -verspreiding, lowergroei en
-funksionering, plantwaterstatus en korrelsamestelling is uitgevoer.
Dit blyk dat edafiese faktore een van die belangrikste parameters is wat wortelontwikkeling
beïnvloed deur beskikbaarheid van grondwater te verander, en wat moontlik fisiese en
chemiese beperkings op wortelgroei kan veroorsaak. Uit die resultate van die studie is dit
duidelik dat intense waterspanning en ‘n pH (KCl) laer as 4.5 ‘n belangrike rol in die beperking
van wortelgroei speel. Aangesien die meeste van die grondsoorte in die Stellenbosch Wyn van
Oorsprong Distrik, veral al die subgronde, suur is, is dit ‘n faktor wat in oorweging geneem moet
word voor aanplantings. Die kombinasie van gunstige edafiese toestande, soos ‘n subgrond
met ‘n pH hoër as 5.0, ‘n lig tot medium tekstuur en matige waterspanning, sal dus aanleiding
gee tot ‘n toename in die groei van dun wortels.
Die effek van lowerbestuur op wortelgroei kan egter nie buite rekening gelaat word nie weens
die belangrikheid daarvan in die variasie van koolhidraataanvraag deur kompeterende
vraagpunte. Hierdie studie toon dat, indien sêkondere lootverwydering tydens ertjiekorrelgrootte
toegepas is, dit aanleiding gee tot ‘n toename in die dun wortels (0.5 tot 2.0 mm). Die
sêkondere blaaroppervlakte verteenwoordig minstens dieselfde blaaroppervlakte as die primêre
blaaroppervlakte in al die wingerde wat ondersoek is, wat dui op die belangrikheid van
sêkondere lote in die totale blaaroppervlakte van die wingerd en die potensiële belangrikheid daarvan in terme van mikroklimaat en blaaroppervlakte wat vir fotosintese beskikbaar is.
Studies van wortelgroei moet lowerargitektuur in ag neem.
39
Mokhtari, Shabestari Mehdi Mokhtari. "Fabrication Of Ceramic Nanofibers And Effect Of Calcination Parameters On Grain Growth." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462018118.
Full text
40
Vedantham, Kumar. "Effect of operating parameters on the growth rate of solution grown crystals." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-07122004-101317.
Full text
41
Mampana, Reedah Makgwadi. "Cropping system effects on soil water, soil temperature and dryland maize productivity." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/43165.
Full textAbstract:
Improved soil water conservation has become an important subject in semi-arid areas due to low and erratic rainfall which is often combined with higher temperatures to provide unsuitable conditions for successful crop productivity. Dryland agriculture remains vulnerable to yield losses in these areas. This calls for implementation of conservation agricultural practices that would improve dryland maize productivity. An on-station field trial was started in 2007 at Zeekoegat experimental farm (24 kilometers north of Pretoria), to establish the effect of different conservation agriculture practices on soil and plant properties. The experimental lay-out was a split-plot randomized complete block design, replicated three times, with each replicate split into two tillage systems (whole plots) and then each whole plot (reduced tillage (RT) and conventional tillage (CT)) was subdivided into 12 treatments (two fertilizer levels x 6 cropping patterns). The present study explored the impacts of different tillage practices, cropping patterns and fertilization levels on soil water content, soil temperature and dryland maize productivity during the 2010/11 and 2011/12 growing seasons. To improve the quality of soil water content (SWC) data, the effect of correction for concretions on soil bulk density and the relationship between volumetric soil water content (SWC) vs neutron water meter (NWM) count ratios was also investigated. Corrections for concretions on soil bulk density did not improve NWM calibrations in this study. In all seasons, significantly higher mean SWC was found under RT treatment than in CT at all depths except at 0-300 mm. For example, during the 2010/11 growing season, SWC under RT was 1.32 % and 1.10 % higher than CT for the 300 – 1350 mm and 0 – 1350 mm soil profiles, respectively. The mean weekly SWC was consistently higher for RT throughout both the growing seasons. Significantly higher SWC was also found under monoculture at all soil depths (except at 0-300 mm during 2011/12) compared to treatments under intercropping. For example, during 2010/11, at 0-300mm, SWC under maize monoculture was 1.72 % higher than under intercropping. The maximum and minimum soil temperatures were significantly higher at 100 and 400 mm soil depths under CT than under RT during 2010/11. During 2011/12, significantly higher minimum soil temperatures at 100 mm depth and lower temperature differences (maximum – minimum soil temperatures) at 400 mm depth were observed under intercropping. Despite the higher SWC and reduced soil temperature under RT, the maize seeds emergence rate was lower and plant stand was reduced. This is attributed to other factors associated with RT systems such as increased soil penetration resistance which often leads to poor root development. The lower soil temperatures under RT were generally within the range that would not be expected to inhibit growth and uptake of nutrients. Slower growth under RT resulted in lower biomass and grain yield. Plants that received high fertilizer rates grew more vigorously than plants under lower fertilizer levels when water was not a limiting factor, but produced lower grain yield due to water shortage in March, especially in 2011/12. The harvest index was therefore lower for treatments that received high fertilizer levels. Maize biomass under monoculture x low fertilizer level was significantly lower compared to other fertilizer x cropping pattern treatments. Maize plant growth under intercropping was improved throughout the seasons, which led to significantly higher grain yield than under maize monoculture. It is therefore recommended that farmers in dryland areas take the advantage of intercropping maize with legumes to obtain higher maize productivity. Further research should focus on investigating the possibility of roots restrictions occurring under RT conditions and under various environmental and soil conditions.<br>Dissertation (MScAgric)--University of Pretoria, 2014.<br>lk2014<br>Plant Production and Soil Science<br>MScAgric<br>Unrestricted
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Ashraf, Zakira Naureen. "Identification of rhizobacteria from rice and maize for plant growth promotion and biological control of rice diseases." Thesis, Lancaster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578244.
Full textAbstract:
The scope of this study was the selection of bacterial strains from rice and maize and evaluation of their potential for plant growth promotion and biological control of rice diseases. 103 bacterial strains isolated from roots, rhizosphere and soil of rice and maize were assayed for production of siderophores, antibiotics, hydrolytic enzymes and HCN. From these, 33 strains were found to produce siderophores, eight were capable of producing diffusible antibiotics and four produced volatile antibiotics, while only one strain was found to produce HCN. Dual culture antagonistic assays were used to select strains capable of inhibiting growth of three major rice pathogens, Xanthomonas oryzae pv. oryzae (bacterial blight), Rhizoctonia solani (sheath blight) and Magnaporthe grisea (rice blast). When inoculated into soils, a number of strains suppressed the incidence of rice blast and sheath blight diseases in two different rice varieties. A strong correlation between siderophore production and in vitro antagonism was found, which extended to biocontrol assays for rice blast disease in the variety Super Basmati, but not Azucena, suggesting that bacterial strains use different mechanisms in suppressing the same pathogen in different rice varieties. As there was no direct contact between the pathogen and bacterial strains, the proposed mechanism for disease suppreSSIOn is induced systemic resistance (ISR). Gene expression analysis for sheath blight experiments confirmed the enhanced induction of chitinase IIb and the peroxidase P0X22.3 by selected bacterial strains. Selected bacterial strains from rice were also observed to enhance plant growth and yield, and this may be related to their ability to fix nitrogen (detected by acetylene reduction assay), solubilize phosphates and/or produce auxin. This study led to the isolation, selection and evaluation of potentially useful bacterial strains from rice and maize that were genetically diverse and persistently abundant in the rhizosphere and can be further utilized for integrated pest management of rice. Moreover, as these strains are . also capable of improving plant health and enhancing grain yield, they could be further utilized either individually or in consortia for integrated nutrient management of rice and maize.
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Otukpa, Faith Obiye. "Metabolomic analysis of maize (Zea mays  L.) seedlings treated with selected plant growth promoting rhizobacteria." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/77875.
Full textAbstract:
Global food production has significantly increased mainly due to the use of high-yield crop varieties, fertilisers, fungicides and pesticides, and improved irrigation methods. Despite the increase in production, there has been a significant cost to the environment in the form of pollution, and to farmers in the form of rising fertiliser and pesticide costs. The impacts on the environment include but are not limited to groundwater contamination, declining soil health and increased pest and pathogen resistance, all which increase the financial cost to farmers. To reverse or rather salvage the situation, more sustainable agricultural practices need to be employed that will maintain high productivity with little to no damage to the environment, and will reduce agrochemical use, thus, reducing the financial strain on farmers. A potential solution would be to exploit soil dwelling rhizospheric microorganisms to improve plant growth with little to no application of agrochemicals.
The rhizosphere refers to the region of soil directly influenced by plant roots and is home to microorganisms known as plant growth promoting rhizobacteria (PGPR). These PGPR have been found to stimulate plant growth via numerous mechanisms, which directly affect the plant metabolome and in turn translates into observable effects in the plant phenotype. The plant metabolome has been described as the bridge between the genotype and phenotype, thus metabolomics acts as a useful tool to evaluate the contribution of external influences on the plant phenotype based on metabolic changes. The effect of PGPR on the plant metabolome is vital in understanding their mode of action, which will further validate their use in farming.
The overall aim of this project was to assess the effect of selected PGPR strains with known plant growth promoting activity on the metabolic profile of maize seedlings; and to evaluate if these changes in the metabolic profile directly correlate with the observable effects on the growth of the seedlings. To achieve this aim, firstly, the effect of Lysinibacillus sphaericus (T19), Paenibacillus sp. (T29) and Bacillus megaterium (A07) on early maize growth, i.e., the effects on dry root and shoot biomass, leaf chlorophyll content, stem diameter and shoot length, was assessed. Secondly, the effect of single strain PGPR inoculation on the metabolic profile of maize was evaluated. Finally, metabolomics analysis was conducted on the roots and shoots of the maize seedlings inoculated with strains T29 and T19 respectively. Statistical analysis of the metabolomics results was conducted to find significant pathways and discriminating metabolites between the control and inoculated plants. To assess the effects of the PGPR strains on early maize growth, a greenhouse trial was first conducted. Non-invasive techniques were used to measure the growth parameters that could be recorded prior to harvest. Next an untargeted metabolomics approach was used to analyse the metabolome of harvested roots and shoots. Metabolomics data acquisition was achieved using ultra-performance liquid chromatography hyphenated to quadrupole time of flight mass spectrometry detection (UPLC/QTOF-MS). Finally, to evaluate the effect of single strain inoculation on the maize root and shoot metabolome, univariate and multivariate methods were applied.
The results of the greenhouse trial showed a tendency of strains T19 and T29 in stimulating shoot growth and root growth respectively in the maize seedlings. Pathway analysis using results from univariate analysis revealed a number of pathways affected by T19 and T29 in the shoots and roots respectively. Multivariate statistical analysis also showed that the inoculated samples differed from the control samples, albeit with varying trends, which indicates differing metabolic states. Some of the metabolic pathways deemed significant in the inoculated shoots and roots were amino acid, nucleotide metabolism or carbon fixation related. A number of discriminating features were found to be differentially regulated in the inoculated roots and shoots. Overall, the results showed that T19 and T29 inoculation stimulated metabolic responses in maize shoots and roots linked to plant growth and development.<br>Dissertation (MSc)--University of Pretoria, 2019.<br>Biochemistry<br>MSc<br>Unrestricted
44
Divsalar, F. "Correlation of mechanical test parameters with fatigue crack growth rates in structural steels." Thesis, Robert Gordon University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234735.
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Mwitwa, Jacob Pacific. "Growth and physiological parameters related to shoot dieback in Pterocarpus angolensis DC seedlings." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/20431.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2004.<br>ENGLISH ABSTRACT:Six experiments, five in the glasshouse and one in the field near Nelspruit, were
carried out to ascertain the effect of factors related to shoot die-back, and of water
treatments on the growth and physiological responses of Pterocarpus angolensis
seedlings. The study was undertaken to broaden the knowledge and understanding of
the phenomenon of shoot die-back in order to enhance our ability to regenerate the
species. The following experiments were carried out
(a) Assessment of biomass accumulation; anatomical characteristics of the shoot
apical meristem; foliar, stem and root concentration of micro- and macronutrients
associated with each phenophase,
(b) Effect of seedling age and seed source on the occurrence of shoot die-back
under field conditions;
(c) Water treatment effects on ChI. afluorescence traits of£'. angolensis seedlings
obtained by assessing the fluorescence yield of photosynthetic samples
subjected to dark- and light-adaptation;
(d) Genetic variation in shoot die-back and other traits of sixteen halfsib families
of £.. angolensis from Malawi, Namibia and Zambia grown over two die-back
seasons.
Experiments conducted revealed the following
1. Patterns of growth observed in phenophases are indicators of seasonal changes in
annual biomass allocation to the shoot and root. Phenophases such as leaf loss
and stem senescence, whether shoot die-back occurs completely or not, are
directly related to the decline in above-ground biomass and declined rate of
increase in root biomass respectively. Leaf flush, expansion and maturation result
in increased biomass accumulation whilst shoot die-back has a minimal downregulatory
effect on root biomass accumulation compared to the shoot. Shoot dieback
is not sudden, therefore from the first day of germination, seedlings
synchronise growth and development with the occurrence of shoot die-back.
2. Phenophasic concentration of foliar N, Ca and Mg, stem Fe and Cu and root
concentrations of P, K, Mg, Fe and B are associated with shoot die-back. Patterns
of mineral nutrient concentration obtained in foliage and roots but to a lesser
extent in the stem, may be related to nutrient remobilisation during shoot dieback.
Higher relative mineral nutrient changes during leaf yellowing and shoot
die-back may be an indication of the removal of significant volumes of mobile
nutrients from senescing tissues.
3. The volume of the shoot apex of E. angolensis remains constant during different
phenophases which points to seasonal uniformity in the size of the apical dome.
Changes in phenology associated with declined growth, or shoot die-back, is
revealed through declined cell number in the tunica which is a reflection of
declined mitotic activity.
4. Shoot die-back occurs in all seedlings from nursery stock planted under field
conditions and all seedlings of up to two years experience complete shoot dieback.
Shoot die-back takes place irrespective of seed source or the age of nursery
stock that is planted. Survival after the first shoot die-back is normally low. Water
treatments had no significant effect on the function of PSIJ reaction centres of P.
angolensis nursery seedlings. In the case of both dark- and light-adapted leaves,
water treatment had no significant effect on the measured Chi. a fluorescence
parameters or the calculated parameters (specific activities, phenomenological
fluxes, structure-function and performance indexes and drivingforces).
5. Water treatments affect the shape of ChI. a fluorescence transients of lightadapted
compared to that of dark-adapted photosynthetic samples of E.
angolensis. No significant water treatment effect was obtained for extracted and
technical Chi. afluorescence parameters, specific fluxes, quantum efficiencies and
phenomenological fluxes. Quantum yield, relative electron transport and quantum
yield limitation, de-excitation rate constants, structure-function, performance
indexes and driving forces were also not significantly different across water
treatments.6. Genetic variation was observed to exist among 16 halfsib families from Malawi,
Namibia and Zambia. High heritabilities were obtained for shoot die-back and
other traits, indicating that shoot die-back is genetically controlled. The trait is
passed from parents to offspring and it is highly probable that it occurs,
throughout its natural range, in all seedlings. Since shoot die-back is genetically
programmed, it remains crucial to the ability of a seedling to regenerate in the
following rainy season<br>AFRIKAANSE OPSOMMING:Ses eksperimente, vyf in die glashuis en een in die veld naby Nelspruit, is uitgevoer
om die effek van faktore wat verwant is aan die terugsterwing van lote op saailinge,
sowel as om die effek van waterstres op die groei en fisiologiese responsies van
Pterocarpus angolensis saailinge, te ondersoek. Die studie is ondemeem om die
kennis en begrip aangaande die regenerasie-dinamika van die spesies te verbeter. Die
volgende eksperimente is uitgevoer:
(a) Evaluering van die effek van jisiologiese veranderings op biomassa; blaar-,
stam- en wortelkonsentrasies van spoor- en makro-voedingselemente, en
anatomiese eienskappe van die apikale meristeem van die lote.
(b) Effek van saailingouderdom en saadbron op die voorkoms van lootterugsterwing
onder veldtoestande.
(c) Waterbehandelingseffekte op Chi. ajluorisensie eienskappe van ,e. angolensis
saailinge wat verkry is deur die jluorisensie te evalueer van fotosintesemonsters
wat aan donker- en lig-adaptasies onderwerp is.
(d) Genetiese variasie in loot-terugsterwing en ander groei-eienskappe van 16
halfsib families van ,e. angolensis vanaf Malawi, Namibia en Zambia wat
gekweek is oor twee terugsterj-seisoene.
Die eksperimente het die volgende aan die lig gebring:
1. Groeipatrone waargeneem gedurende die fenofases is indikatore van seisoenale
veranderings in jaarlikse biomassa allokasies aan die loot en die wortels.
Fenofases soos blaarverlies en lootafsterwing, ongeag of loot-terugsterwing
volledig is of nie, is direk verwant aan die afname in bogrondse biomassa en
afnemende tempo van toename in wortelbiomassa respektiewelik. Bottende blare,
vergroting en rypwording van blare lei tot toenemende biomassa akkumulasie
terwyl loot-terugsterwing 'n minimale afskalende effek op akkumulasie van
wortelbiomassa het in vergelyking met die van die loot. Loot-terugsterwing is nie
skielik, met ander woorde vanaf die eerste dag van ontkieming sinchroniseer
saailinge groei en ontwikkeling met die voorkoms van loot-terugsterwing.
2. Fenofase konsentrasies van en veranderings in blaar N en Ca en loot Fe, asook
veranderings in waargenome wortel N, K, Ca, Mn, Cu, Zn en B is sterk geassosieer
met loot-terugsterwing. Patrone van minerale
voedingselementkonsentrasies wat in blare en wortels, en in minder mate in die
loot, verkry is, mag direk verwant wees aan hermobilisering van
voedingselemente gedurende loot-terugsterwing. Hoe relatiewe minerale
voedingselementveranderings gedurende die vergeling van blare en lootterugsterwing
mag 'n indikasie wees van die verwydering van betekenisvoUe
hoeveelhede mobiele nutriente vanaf sterwende weefsel.
3. Die volume van die groeipunt van r. angolensis bly konstant gedurende
verskillende fenofases wat dui op seisoenale uniformiteit in die grootte van die
apikale koepel. Veranderings in fenologie ge-assosieer met afnemende groei, of
loot-terugsterwing, word gerejlekteer deur afnemende selgetaUe in die tunika wat
dui op afnemende mitotiese aktiwiteit.
4. VoUedige loot-terugsterwing kom voor in aUe saailinge vanaf die kwekery wat in
die veld geplant word tot op die ouderdom van twee iaar. Dit kom voor angeag
van saadbron of ouderdom van saailinge ten tye van planting. Oorlewing na
aanvanklike loot-terugsterwing is normaalweg laag.
5. Water behandelings het geen beduidende effek op die funksie van PSII
reaksiesentra van r. angolensis kewekery-saailinge gehad. Vir beide donker- en
lig-aangepaste blare is geen beduidende waterbehandelingseffek verkry vir
waargenome ChI. a jluoresensie parameters of die berekende parameters
(spes ifieke aktiwiteite, jenomenologiese jlukse, struktuur-funksie-indekse,
"perjormance-indekse oj" driving forces" ).
6. Genetiese variasie tussen 16 halfsibfamilies vanaf Malawi, Namibie en Zambie is
verkry vir loot-terugsterwing en ander groei-eienskappe. Dit dui op genetiese
beheer van terugsterwing en dat die eienskap oorerjbaar is, en waarskynlik in die
hele natuurlike verspreidingsgebied van die spesies in aUe saailinge voorkom.
Aangesien loot-terugsterwing gene ties geprogrammeer is, is dit noodsaaklik vir
die vermoe van die plant om in die volgende reenseisoen te regenereer.
46
Yi, Sheng. "Transforming growth factor beta 1 modulates electrophysiological parameters of vas deferens epithelial cells." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16898.
Full textAbstract:
Doctor of Philosophy<br>Department of Anatomy and Physiology<br>Bruce Schultz<br>Transforming growth factor β1 (TGF-β1) is a cytokine that reportedly affects the severity of cystic fibrosis lung disease. The goal of this project was to define the effect of TGF-β1 on vas deferens, an organ that is universally affected in male cystic fibrosis patients.
In the first study, experiments were conducted using freshly isolated porcine vas deferens epithelial cells. Primary porcine vas deferens epithelial cells exposed to TGF-β1 exhibited a significantly reduced basal transepithelial electrical resistance (Rte). TGF-β1-induced reduction in Rte was prevented by SB431542, a TGF-β receptor I inhibitor, indicating that the effect of TGF-β1 requires the activation of TGF-β receptor I. Western blot and immunohistochemistry results showed the expression of TGF-β receptor I in native vas deferens epithelia, indicating that the impaired barrier function and anion secretion that were observed in cultured vas deferens cells can likely be observed in the native context. Immunohistochemical outcomes showed that TGF-β1 exposure led to loss of organization of tight junction proteins occludin and claudin-7. These outcomes suggest that TGF-β1 impairs the barrier integrity of epithelial cells lining the vas deferens.
In a parallel study that employed PVD9902 cells that are derived from porcine vas deferens, TGF-β1 exposure significantly reduced anion secretion stimulated by forskolin, forskolin/IBMX, and 8-pCPT-cAMP, suggesting that TGF-β1 affects downstream targets of the cAMP signaling pathway. Real-time RT-PCR and western blot analysis showed that TGF-β1 exposure reduced both the mRNA and the protein abundance of cystic fibrosis transmembrane conductance regulator (CFTR). Pharmacological studies showed that the inhibitory effect of TGF-β1 on forskolin-stimulated anion secretion was abrogated by SB431542 and attenuated by SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor. These outcomes suggest that TGF-β1, via the activation of TGF-β receptor I and p38 MAPK signaling, reduces CFTR expression, and thus impairs CFTR-mediated anion secretion.
Outcomes from these studies suggest that, in epithelial cells lining the vas deferens, TGF-β1 exposure leads to an impaired physical barrier and/or reduced anion secretion, which is expected to modify the composition and the maintenance of the luminal environment and thus, is expected to reduce male fertility.
47
Santana, Maria Gabrielle Sousa de. "Efect of sewage wastewater reuse of the parameters of growth and nutrition sorgo." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16322.
Full textAbstract:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior<br>The wastewater reuse for irrigation crops has many ecological and economic advantages, for example: nutrients recycling, reducing pollution, fertilizer and water economy. Therefore, the reuse of wastewater is an alternative to regions with water deficit, especially in urban and industrial areas. Sorghum is an important crop produced by family farmers in the semiarid region and used in animal feed. Produced under rainfed conditions, the use of irrigation becomes an alternative to stability in production. The research was conducted in EstaÃÃo MeteorolÃgica do Centro de CiÃncias AgrÃrias da Universidade Federal do CearÃ. The effluent used was collected in EstaÃÃo de Tratamento de Esgotos do Campus do Pici (ETE-PICI) da Universidade Federal do Cearà (UFC), which receives wastewater with sewage characteristics. 10 treatments were used in a completely randomized design with 4 replications. Where: T1 supply water without chemical fertilizers; T2 supply water with 25% of recommended mineral fertilization; T3 supply water with 50% of recommended mineral fertilization; T4 supply water with 75% of recommended mineral fertilization; T5 supply water with 100% of recommended mineral fertilization T6- effluent water without chemical fertilizers; T7- effluent water with 25% of recommended mineral fertilization; T8 effluent water with 50% of recommended mineral fertilization; T9- effluent water with 75% of recommended mineral fertilizer and T10 effluent water with 100% of recommended mineral fertilization. The plant height, stem diameter, number of leaves at 20 days, showed no variation in type of water applied. However, the variables showed significant difference related to the doses of N, P and K. The variables analyzed (Plant height, number of leaves, leaf area, stem diameter) at 40 days after sowing, had significant difference only for the N levels, P and K. The nutrients P and S showed statistical differences in the interaction. The nutrients K and Ca obtained significant results at 1% over the interaction. The nitrogen contents showed a significant difference as the nitrogen rates, P and K, but did not fit any regression model. The treated sewage effluent can be used for irrigation of crops provided a controlled and well managed.<br>A reutilizaÃÃo de Ãguas residuÃrias na irrigaÃÃo apresenta incontÃveis vantagens ecolÃgicas e econÃmicas, dentre elas estÃo: a reciclagem dos nutrientes, reduÃÃo da poluiÃÃo, economia de fertilizantes e Ãgua. Portanto, o reÃso de efluente domÃstico se mostra como uma alternativa para regiÃes com dÃficit hÃdrico, principalmente em zonas urbanas e industriais. O sorgo à uma cultura relevante produzida pela agricultura familiar na regiÃo semiÃrida e usada na alimentaÃÃo animal. Produzido em condiÃÃes de sequeiro o uso da irrigaÃÃo torna-se uma alternativa para estabilidade na produÃÃo. A pesquisa foi realizada na EstaÃÃo MeteorolÃgica do Centro de CiÃncias AgrÃrias da Universidade Federal do CearÃ. O efluente utilizado no estudo foi coletado na EstaÃÃo de Tratamento de Esgotos do Campus do Pici (ETE-PICI) da Universidade Federal do Cearà (UFC), que recebe Ãguas residuÃrias com caracterÃsticas de esgoto domÃstico. Foram utilizados 10 tratamentos em delineamento inteiramente casualizado com 4 repetiÃÃes. Sendo: T1- Ãgua de abastecimento sem adubaÃÃo mineral; T2- Ãgua de abastecimento com 25 % da adubaÃÃo mineral recomendada; T3 - Ãgua de abastecimento com 50% da adubaÃÃo mineral recomendada T4- Ãgua de abastecimento com 75% da adubaÃÃo mineral recomendada; T5- Ãgua de abastecimento com 100% da adubaÃÃo mineral recomendada T6- Ãgua de efluente sem adubaÃÃo mineral; T7- Ãgua de efluente com 25% da adubaÃÃo mineral recomendada; T8- Ãgua de efluente com 50% da adubaÃÃo mineral recomendada; T9- Ãgua de efluente com 75% da adubaÃÃo mineral recomendada e T10- Ãgua de efluente com 100% da adubaÃÃo mineral recomendada. A altura das plantas, diÃmetro do colmo, nÃmero de folhas aos 20 dias nÃo apresentaram variaÃÃo em relaÃÃo ao tipo de Ãgua aplicado. No entanto, as variÃveis analisadas mostraram diferenÃa significativa apenas quanto Ãs doses de N, P e K aplicadas. As variÃveis analisadas (Altura das plantas, nÃmero de folhas, Ãrea foliar, diÃmetro do colmo) aos 40 dias apÃs a semeadura obtiveram diferenÃa significativa somente quanto Ãs doses de N, P e K aplicadas. Os nutrientes P e S mostraram diferenÃa significativa a 5% com relaÃÃo a interaÃÃo. Os nutrientes K e Ca obtiveram resultados significativos a 1% com relaÃÃo as interaÃÃo. Os teores de nitrogÃnio apresentaram diferenÃa significativa a 5% de significÃncia quanto Ãs doses de N, P e K aplicadas, mas nÃo se adequaram a nenhum modelo de regressÃo. O efluente de esgoto tratado pode ser utilizado na irrigaÃÃo das culturas desde que de forma controlada e bem manejada.
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Fidantemiz, Yavuz F. "Effect of Water Table Level on Soybean Water Use, Growth and Yield Parameters." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/29277.
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Responses of soybean (Glycine max) water uptake and crop growth to four constant water table depths (30, 50, 70, and 90 cm) were studied under a controlled environment using lysimeters. Additionally, control lysimeters with irrigation and no water table were used for comparison. A randomized complete block design (RCBD) was used with six replications in each treatment. The results indicated that the water table depths of 30, 50, 70 and 90 cm contributed to 77, 71, 65 and 62% of soybean water use, respectively. Thus, the water use efficiency, total grain yield (g lysimeter-1) per unit water use (mm) was 0.008, 0.022, 0.018, 0.025, and 0.031 for irrigation, 30, 50, 70, and 90 cm water table depth treatments, respectively. Soybean was found to be tolerant to shallow groundwater conditions, and root mass distribution in the soil profile was significantly influenced by the presence of shallow water table depths.<br>North Dakota Water Resources Research Institute<br>North Dakota Agricultural Experiment Station (Fargo)
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Combs, Stephen H. "Physical and chemical effects of pelleting feed on broiler growth and behavioral parameters." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/90926.
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Barred Rock chickens were offered diets that had been pelleted at 55° or 85°C. In an 8-week feeding trial, the subjects receiving pellets processed at the higher temperature experienced significant (P ≤ .05) weight gain over those receiving the diet processed at 55°C. Although feed consumption for this treatment increased as well, the difference was not significant (P ≤ .05). Chemical investigation revealed that metabolizable energy and bioavailability of lysine of both heat treatments were similar. Starch availability as measured by in vitro enzyme susceptibility, however, was lowered by increased heat application.
In a second experiment, the feeding behavior of 12-16 week old cockerels offered diets of varying particle size, resulted in significant (P ≤ .05) increases in feed consumption rate and therefore decreases in total feeding activity for birds offered pellets and crumbles as compared to mash and reground pellets. No differences were noted in meal size, meal frequency, interval between meals, or total consumption.
In a parallel experiment, no differences were noted in the behavioral parameters of birds receiving diets pelleted at 55, 70, or 85°C of similar density and particle size. Mash controls, however, experienced significantly (P ≤ .05) decreased consumption rate and concurrent increase in feeding activity.
The beneficial effects experienced with pelleting can therefore be attributed to the reduction in total feeding activity that allows an increased proportion of net energy to be utilized in support of growth.<br>M.S.
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Istain, Brandon. "Isolation and characterization of plant growth promoting endophytic bacteria from Medicago lupulina for enhanced drought tolerance in Maize." University of the Western Cape, 2019. http://hdl.handle.net/11394/7870.
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>Magister Scientiae - MSc<br>Maize is one of the major staple foods in many African nations however, this crop is sensitive to environmental stressors. Drought is a major environmental stressor affecting maize production. Due to global warming, drought episodes are expected to increase in duration and frequency. Therefore, it is vital to improve maize drought tolerance thereby increasing food security. Many studies have looked at improving maize drought tolerance through genetic engineering techniques which has shown promising results, nonetheless GMOs have been under scrutiny due to public concerns regarding unknown side effects.<br>2024-02-24