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1
Bo, Sann. "Functional Trait Based Community Assembly in a Secondary Tropical Dry Forest (熱帯乾燥地の二次林における機能形質に基づいた群集形成)". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225668.
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Clarke, Jodie Johnson. "Development of a Greenhouse Tobacco Seedling Performance Index." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33863.
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Tobacco seed performance is traditionally measured as percentage
germination at 14 d under controlled laboratory conditions. However, under
greenhouse conditions, seed lots with equal 14-d germination may exhibit
substantial differences in uniformity of early seedling growth and spiral root
incidence that impact the number of usable transplants. A seedling performance
index (SPI) was developed to quantitatively describe greenhouse tobacco seedling
performance. The 14-d emergence, relative leaf area uniformity, and seedling leaf
area determined by computer image analysis were used to calculate the index.
Greenhouse tobacco seed trials demonstrated that seed with the Rickard pellet had
higher emergence, but the higher spiral root incidence associated with the Rickard
pellet lowered the SPI compared to the Cross Creek pellet. Primed seed lots of
flue-cured cultivars (NC 72 and NC 71) had a significantly higher SPI than the
nonprimed seed lots at one location but not at a second location. Seed lots sown
in Premier Pro-Mix TA commercial medium had a higher spiral root incidence,
which resulted in a lower SPI compared to Carolina Choice, Carolina Gold, and
Sunshine LP5 commercial media. The index quantitatively determined
differences in seedling performance under greenhouse conditions not reflected by
standard germination tests. Significant differences in the SPI were observed
among seed lots with certified 90% germination. The SPI is a simple method to
describe seedling performance because the data used to calculate the SPI is
obtained from one seed tray image. In contrast, frequent counting and seedling
evaluations are involved with standard germination and vigor tests.<br>Master of Science
3
Holgén, Per. "Seedling performance, shelter tree increment and recreation values in boreal shelterwood stands /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5854-4.pdf.
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Crowell, Michelle Dawn. "Performance of Pinus sylvestris seedlings in a restoration of Caledonian forest." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624989.
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England, David M. "Seeding Treatments to Enhance Seedling Performance of the Bulrushes Bolboschoenus Maritimus, Schoenoplectus Acutus and S. Americanus in Wetland Restorations." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7659.
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A major goal in restoration is to reestablish native plant communities. There are several ways to reestablish species, but for large areas the most logistically feasible approach is to sow seed of desirable species. However, most wetland seeds are buoyant and are extremely difficult to establish in designated areas before floating away. In upland areas, tackifiers have been used to stabilize hill slopes from erosion and to keep seeds in place. The tackifier works as an adhesive that binds the seeds to the soil. However, the use of a tackifier has not been widely employed in wetland restorations, and prior to its broad implementation into wetland restoration practice, it is important to determine if tackifiers will hold up in wetland conditions. In greenhouse studies, we tested the effectiveness of different tackifier types and concentrations on Bolboschoenus maritimus seedling emergence, the influence of soil moisture and flooding on the duration of tackifier effectiveness, the effect of a mulch addition on tackifier effectiveness (Bolboschoenus maritimus, Schoenoplectus acutus and S. americanus), the effectiveness of pre-germination in enhancing Bolboschoenus maritimus seedling emergence using a tackifier, and the effectiveness of tackifier over time. We concluded that the use of a tackifier was effective at keeping seeds from washing away for at least 15 days, a mulch addition did not enhance tackifier effectiveness, and pre-germination did not benefit B. maritimus seedling emergence. The results from this study provide strong evidence that the use of a tackifier could be an effective solution to establish bulrush species in designated areas in wetland restorations.
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Wyss, Lozano Hoyos Tania. "Pinus elliottii var. densa Seedling Performance Reflects Ectomycorrhizas, Soil Nutrient Availability and Root Competition." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/496.
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Ectomycorrhizas generally improve seedling mineral nutrition and growth, so I hypothesized that decline of the Florida native pine variety Pinus elliottii var. densa Little & Dorman is related to deficiency of appropriate ectomycorrhizal (ECM) fungi in the pine's native flatwoods. At Archbold Biological Station I examined how quickly ECM fungi colonize P. elliottii var. densa seedlings and I compared the effect of local absence versus presence of adult pines on ECM colonization and pine seedling performance. Under controlled greenhouse conditions, I investigated how a wide range of ECM colonization and spread of extraradical mycelium throughout a large volume of relatively infertile, flatwoods soil enhance the mineral nutrition and growth of pine seedlings. In a field bioassay, I transplanted two-month-old pine seedlings to three flatwoods sites with low (4 pines/400 square m), medium (9 pines/400 square m), and high (19 pines/400 square m) adult pine densities. I subsequently excavated seedlings every two weeks for four-and-a-half months and determined their ECM colonization, response to shade, and response to surrounding grass density. Across all sites, pine seedlings in high shade had a higher mean chlorophyll concentration and lower stem dry weight than in full sun. Competition with grass reduced seedling survival and stem dry weight. Initial colonization was rapid and not different among sites, with 5.4 % of roots colonized 15 days after transplant. Pine seedlings had midpoint means of 29.5 %, 18.1 % and 21.3 % ECM root tips in low, medium and high adult pine density sites, respectively, suggesting that pine seedlings establishing in flatwoods encounter sufficient ECM fungi to support their growth, regardless of adult pine density. In a field experiment, I determined in the presence versus absence of adult pines if pine seedlings had higher ECM colonization and consequent improved survival, mineral nutrition, and growth. Within and beyond pine stands, I transplanted seedlings into intact or drilled, hyphae in-growth pipes buried in the ground. I placed autoclaved or fresh ECM root inoculum in two sets of intact pipes, and autoclaved inoculum in drilled pipes into which mycorrhizal hyphae could extend from the surrounding vegetation. Seven-and-a-half months after transplant, ECM hyphae had penetrated the drilled pipes and colonized pine seedlings, but roots from the surrounding vegetation also penetrated pipes. Extraneous roots reduced the survival of seedlings both within and beyond pine stands, but extraneous roots reduced seedling growth only beyond pine stands. Because percentage ECM root tips was higher in the presence (53 %) than in the absence (38.8%) of adult pines, pine stands might benefit the competitive ability of seedlings by increased ECM colonization and possibly by common mycorrhizal networks connecting seedlings to adults. Because beneficial effects of ECM in the field were small, I also examined ECM effects on pine seedlings in a greenhouse experiment. I manipulated ECM fungus colonization and the volume of flatwoods soil to which extraradical mycelium had access. In a small volume of soil (220 mL), fresh ECM root inoculum promoted the mycorrhizal colonization of seedlings versus those receiving autoclaved roots, but seedling growth and uptake of Mg, Ca, and Zn was lower with fresh than with autoclaved root inoculum. Growth and mineral nutrient uptake likely was enhanced by a pulse of nutrients from autoclaved roots, but for inoculated plants may have been reduced because of nutrient retention by saprotrophic microorganisms degrading fresh ECM roots and because of mineral nutrient retention by ECM fungi. Ectomycorrhizal seedlings with extraradical mycelium access to a large soil volume had higher mean chlorophyll concentration than those in a small soil volume. Weekly disturbance of the extraradical mycelium, however, reduced foliar contents of Mn, K, P, N, and Zn by one-third to one-half, and reduced needle dry weight of seedlings by one-third, demonstrating the importance of extraradical mycelium accessing a large volume of soil when it is nutrient-poor. My research demonstrates that ECM fungi are widespread in flatwoods and rapidly colonize pine seedlings. ECM fungus inocula are greater in the presence than in the absence of adult pines, and ECM or seedlings' connections to a common mycorrhizal network improve seedlings' belowground competitive ability. ECM especially enhance seedling mineral nutrition and growth when undisturbed, extraradical mycelium extends throughout a large volume of soil. Populations of Pinus elliottii var. densa might best regenerate in flatwoods if seedlings recruit near adult pines and where there is little competition for light, water, and mineral nutrients.
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Cloutier, Renée R. "Effects of nutrient addition mode on jack pine, Pinus banksiana Lamb., seedling outplanting performance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/MQ31420.pdf.
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Németh, M. Barbara. "Pollen Performance and Seedling Vigor in Laboratory and Natural Populations of Clarkia Unguiculata (Onagraceae)." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1117816212.
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Serafim, João Afonso Machado Pinto de Aguiar. "Assessing the role of macro- and microclimate on Holm oak performance in Mediterranean drylands." Master's thesis, ISA, 2019. http://hdl.handle.net/10400.5/21285.
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Mestrado em Biologia dos Recursos Vegetais / Instituto Superior de Agronomia / Faculdade de Ciências. Universidade de Lisboa<br>Mediterranean drylands are expected to become drier due to climate change. This may aggravate desertification by increasing dryland susceptibility to land degradation, leading to the loss of biodiversity and ability to provide ecosystem services. In Mediterranean Basin drylands, a large area is occupied by oak woodlands, a semi-natural agro-silvopastoral system called Montado in Portugal. In the drier areas, where Montado seems to act as a buffer against desertification, the dominant tree species is Holm oak (Quercus ilex subsp. rotundifolia), However, in the last decades, a declining trend has been reported for Holm oak woodlands, mostly attributed to unsustainable land management, biotic factors and to an increase in aridity at a regional scale. Also, at a local scale, it has been shown that microclimate conditions driven by topography have a major influence on this species natural regeneration rates. Over the last decades, many (re)afforestation with Holm oak have been implemented to revert Montado’s decline and combat desertification, although not always successful.
The aim of this work was to study the effect of macro- and microclimate on Holm oak performance, specifically on acorn germination and first summer seedling survival. Holm oak acorns were collected along a climatic gradient based on long-term precipitation (30 yrs.), resulting in 6 macroclimate provenances. In 2 sites, the driest and the wettest sites of the gradient, areas with contrasting microclimates were selected using Potential Solar Radiation (PSR) as a proxy of microclimate conditions. Holm oak performance was, thus, studied along a macroclimate gradient and in microclimate contrasting conditions.
Holm oak acorns from each provenance where characterized biometrically and acorn production evaluated. Germination of acorns and seedling survival were evaluated under greenhouse similar conditions and in the field under contrasting macro- and microclimate conditions.
We found that macro- and microclimatic provenance influences acorn size and germination. Drier sites and more exposed areas (higher PSR) had bigger acorns with higher germination. Field conditions did not seem to affect germination but rather the first summer seedling survival. The survival of Holm oak seedlings to the first summer was significantly higher in the wetter site and in less exposed areas than in the drier site and in more exposed areas.
This work provides guidelines to increase Holm oak seedling quantity and quality in nurseries to be used in (re)afforestation plans and to improve Holm oak young seedling survival, either by focusing (re)afforestation in microclimatic favorable areas (using remote sensing derived information like PSR), or by providing additional assistance to seedlings growing in drier and/or more exposed areas. In addition, it may also help to better understand Holm oak seedling mortality and/or natural regeneration patterns. Hence, these findings may contribute to improve the success of Holm oak (re)afforestation as a critical restoration tool to combat desertification in Portuguese drylands, and revert Holm oak Montado’s decline, particularly under a climate change scenario<br>N/A
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Correia, António Henrique Costa Gomes Soares. "Designing Eucalyptus globulus Labill. seedlings morphology using nitrogen fertilization during nursery production." Master's thesis, ISA, 2010. http://hdl.handle.net/10400.5/15195.
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Mestrado em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia<br>A Eucalyptus globulus Lab. Situa-se como a terceira espécie mais importante ao
nível da área florestal Nacional, de extrema importância na indústria florestal,
utilizada como material base na produção de pasta de papel (CELPA, 2009).
Neste trabalho produziram-se plantas de Eucaliptus globulus, utilizando quatro
níveis de fertilização, em condições semelhantes às utilizadas em viveiros
comerciais com o objectivo de (1) modelar o crescimento (dimensões das plantas
e periodo de produção), tendo em conta os limites legais morfológicos impostos
por decreto lei (Decreto-Lei) e (2) desenvolver indicadores de qualidade das
plantas de forma a estimar a sua performance no campo. Os resultados
demonstram que existiu correlação entre crescimento de raízes finas e a
performance no campo. A correlação observada entre conteúdo de clorofila e o
conteúdo em azoto das plantas permite optimizar a produção, pela avaliação das
necessidades em azoto que as plantas apresentem. A fertilização azotada revelou
um grande impacto no crescimento potencial das raízes. O fornecimento de 40
mg de N (nível de fertilização N40) produz plantas com maior capacidade de
sobrevivênvia e performance, aplicado a partir dos 2 meses de produção--------------------------------ABSTRACT - Tasmanian blue gum (Eucalyptus globulus Labill) is the third most important
specie in the Portuguese forest cover, highly relevant in the forestry industry, and
raw material used for pulp and paper production (CELPA, 2009). Growth of this
short rotation species in the field is dependent on the initial growth in the nursery.
In this experiment, seedlings of Eucalyptus globulus Labill were grown with four
levels of Nitrogen (N) fertilization, under growth conditions similar to those used
in nursery commercial production, with the objectives of (1) modelling growth
(planting stock size and production period), taking into account the legal
regulation limits imposed by law (Decreto-Lei) and (2) to develop indicators of
seedlings quality to estimate their performance in the field. Results showed high
correlation between fine roots growth and field performance. The correlation
between chlorophyll content and N seedling content observed allows to optimize
seedling production, through the assessment of N needs of seedlings. N nutrition
reveals high impact on root growth potential. 40 mg of total supplied N (N40
nutrition level) produces good quality seedlings, applied since 2 month seedlings<br>N/A
11
Bloor, J. "Effects of light on the performance of shade-tolerant tropical rainforest tree seedlings." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596725.
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This thesis set out to investigate the light responses of shade-tolerant tropical tree species, and to assess whether or not there was a trade-off between shade tolerance and responsiveness to high light. Shadehouse experiments indicated that low-light relative growth rate was positively correlated with that of high light across species, and all seedlings showed typical 'sun' and 'shade' characteristics when grown in high- and low-light survival amongst the species studied. These trends were mirrored in forest-growth plants. Seedling mortality rate in the forest varied across species and was driven by vertebrate herbivory rather than light availability. In the shadehouse studies, seedling light responses did not appear to be confounded by nutrient limitation. Some evidence was found for phylogenetic effects across species, particularly in root morphology. Ontogenetic effects were also found for a number of plant traits, although the significance of these effects was not consistent across species. Species showed changes in growth ranking both across light levels and over time, suggesting a role for shifting competitive hierarchy in promoting species coexistence. The shade-tolerant species studied also varied significantly in the flexibility of their plant traits in response to changes in light conditions. Nonetheless, all species showed significant acclimation to an increase in light in terms of growth, photosynthesis, morphology and architecture. Acclimation to a decrease in light involved a significant decrease in photosynthetic rate and growth across species, but changes in morphology were limited.
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Barden, Charles J. "Root growth potential and outplanting performance of loblolly pine seedlings raised at two nurseries." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91032.
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Root growth potential CRGP) is the measure of seedling ability to grow new roots. Loblolly pine (Pinus taeda L.) seedlings from 5 seedlots were raised at two widely separated nurseries (Summerville, SC and New Kent, VA). In Experiment I, RGP was determined during the fall and winter of 1984-85 and 1985-86, and several morphological traits were measured. In Experiment II seedlings from the same seedlots were lifted during February 1985 and 1986 at both nurseries, and cold stored until subsequent outplanting; subsamples of outplanted seedlings were used for RGP determinations.
Root growth potential varied significantly by family, nursery, and lift date, and first order interactions were significant. Generally, the RGP of Summerville raised seedlings was higher than that of New Kent raised seedlings. RGP was not strongly correlated with common measures of shoot morphology, but RGP was consistently well correlated with lateral root dry weight.
In Experiment II, RGP varied significantly by family, nursery, and storage duration. The family x nursery effect was the only significant interaction. Summerville raised seedlings had higher RGP on each planting date. During each year RGP declined rapidly in storage. First year survival was significantly correlated with RGP (r = .52, p < .001). Height increment and RGP were also strongly correlated (r = .80, p < .001). These relationships and their implications for nursery management were discussed.<br>M.S.
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Piechowski, Daniel. "Reproductive ecology, seedling performance, and population structure of Parkia pendula in an Atlantic forest fragment in Northeastern Brazil." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60306.
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Shiroma, Amarilís Thieme. "Sistema de indicadores aplicado à agricultura irrigada." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-15032019-125427/.
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O manejo da irrigação na produção de mudas de hortaliças é caracterizado como uma atividade complexa, pois são cultivadas, em um mesmo ambiente, diversas espécies com necessidades hídricas e estádios fenológicos diferentes. Além disso, este setor está inserido em um mercado extremamente competitivo, o que faz com que a melhoria contínua dos processos se torne essencial para a sobrevivência do negócio. Em função da importância do sistema de medição de desempenho como instrumento de auxílio à gestão, o presente trabalho teve como objetivo propor um conjunto de indicadores de desempenho que permita a avaliação dos processos operacionais de produção de mudas de hortaliças folhosas. O estudo, classificado como uma pesquisa qualitativa do tipo exploratória, foi desenvolvido a partir do referencial teórico e de informações técnicas obtidas nos viveiros. O trabalho foi dividido, basicamente, em três etapas: na definição dos objetivos da produção de mudas, no mapeamento dos processos envolvidos e, por último, na seleção dos indicadores de desempenho que mais se adequam aos processos. Foram identificados quarenta e cinco indicadores de desempenho na literatura, sendo que seis foram selecionados como indicadores-chave.<br>Irrigation management in the production of vegetable seedling is characterized as a complex activity, since several species with different water needs and different phenological stages are cultivated in the same local. In addition, this sector is embedded in an extremely competitive market, which means that the continuous improvement of processes becomes essential for the survival of the business. Due to the importance of the performance measurement system as an aid to management, the present work had the objective of proposing a set of performance indicators that allow the evaluation of the operational processes of vegetable\'s seedlings production. The study, classified as a qualitative research of the exploratory type, was developed based on the theoretical reference and the technical information obtained from the nurseries. The work was basically divided in three stages: the definition of the objectives of the production of seedlings, the mapping of the involved processes and, finally, the selection of the performance indicators that best suit the processes. Forty five performance indicators were identified in the literature, of which six were selected as key indicators.
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Leclerc, Yves. "Acclimatization, field performance and microtuberization of tissue cultured potato (Solanum tubererosum L.) cv. Russet Burbank." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61861.
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Keammerer, Holly Barton 1983. "Community structure, plant interactions, seedling performance and seed bank composition of salt marshes along an estuarine gradient in Coos Bay, Oregon." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11256.
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xviii, 160 p. : ill. (some col.)<br>Salt marshes are intertidal communities dominated by halophytic vascular plants that are subjected periodically to tidal inundation. These species have developed various adaptations to this stress, including tolerances of fluctuating salinity, extended periods of inundation and intervals of anoxic conditions. The marshes are divided into zones of different plant communities based on species' tolerances of ambient estuarine conditions.
Abiotic stresses change along the estuarine salinity gradient (marine to riverine), potentially altering development and composition of plant communities. Abiotic gradients associated with tides are not the only factors that contribute to development of plant community composition in salt marshes. Both negative (competition) and positive (facilitation) biological interactions are also important. Factors that influence community structure in salt marshes, particularly on the eastern North American seaboard, have been well studied. In contrast, salt marshes along the Oregon coast are smaller and more discrete and have received comparatively little attention.
The community structure and seed bank composition of six marshes along an estuarine salinity gradient were evaluated. Four major community types dominated marshes that varied in the salinity of inundating tidal waters. Community types were relatively consistent throughout the estuary despite the distances between the marshes. Unlike the emergent plant communities, marsh seed bank composition was more similar within a marsh than within a community type.
The low and high marsh community types were separated by a distinct boundary in the marine marshes. Although abiotic factors influence the physical separation of communities, competitive interactions commonly determine the upper limit of a species. In Metcalf marsh, however, the upper boundary for two dominant low marsh species was not determined by competition with the high marsh dominant species.
Positive biotic interactions between seedlings and existing vegetation in a community are important factors in determining species distributions, particularly in stressful estuarine environments. In salt marshes, where abiotic stress can be harsh, presence of existing vegetation can ameliorate these conditions and enhance germination and seedling establishment. However, interaction between seedlings and the emergent marsh community was highly competitive, though germination of one species was enhanced in the presence of existing vegetation.
This dissertation includes un-published co-authored material.<br>Committee in charge: Dr. Scott Bridgham, Chairperson;
Dr. Richard Emlet, Advisor;
Dr. Steven Rumrill, Member;
Dr. Alan Shanks, Member;
Dr. Gregory Retallack Outside Member
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Weerasooriya, Dilooshi Kumari. "Genetic analysis of interveinal chlorosis and reduced seedling vigor as related to agronomic performance in sorghum resistant to ALS inhibitor herbicides." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32896.
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Doctor of Philosophy<br>Department of Agronomy<br>Tesfaye T. Tesso<br>The lack of effective post-emergence weed control options is often highlighted as one of the major factors behind dwindling acreage under sorghum (Sorghum bicolor (L.) Moench) in the United States. The discovery of herbicide resistance sources in wild sorghum population and subsequent efforts to incorporate them into cultivated sorghum was received with much optimism to change weed management practices in sorghum. As the development of the technology advances, especially of the Acetolactate synthase (ALS) resistance, concerns over the temporary interveinal chlorosis and reduced seedling vigor in some of the resistant families became heightened. This thesis research is designed to shed light on the genetic basis of seedling chlorosis and assess its impacts on yield potential.
The study has three parts; the first part is focused on identifying the genetic causes and plant mechanisms associated with the chlorotic phenotype. ALS herbicide resistant sister-lines expressing normal and chlorotic phenotypes were analyzed via RNA sequencing at four time points during seedling growth. The study identified several variants of genes coding chloroplast precursors and those that cause epigenetic modifications. Once confirmed, genetic markers can be developed to track these gene variants in the breeding population and eliminate segregates genetically prone to chlorosis/yellowing.
The second part of the study focuses on assessing the effect of ALS resistance associated chlorosis on agronomic and nutritional parameters of sorghum inbred lines. A set of ALS resistant lines expressing different levels of the chlorotic phenotype were evaluated in replicated field trials and laboratory methods. Results showed that interveinal chlorosis delays flowering but does not have negative effect on yield and nutritional parameters with and without herbicide treatment. The last part addresses whether there is any yield drag that may be associated with herbicide resistance traits and foliar interveinal chlorosis. For this, we synthesized a large set (182) of hybrids from ALS resistant, ACCase resistant and regular (susceptible) seed and pollinator parents. The hybrids were then evaluated in three sets at multiple locations during the 2014 and 2015 crop seasons along with commercial checks. The results revealed that resistance to both herbicides do not cause any drag to grain yield. The traits also do not have any negative impact on grain and nutritional quality of resistant hybrids.
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Jessen, Maria-Theresa. "Effects of climate warming on the performance of three boreal tree seedling species in interaction with moss cover and fire history." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-136177.
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Forest regeneration in the form of successful seedling establishment is a key factor for the persistence of a healthy forest ecosystem. Tree seedlings grow in a complex environment shaped by over- and understory and competition for light, nutrients and water. Not much research has been done on how climate change is impacting on seedling performance through direct and indirect warming effects including possible interactions with the growth environment i.e. understory vegetation. To elucidate these, seedlings of B. pubescens, P. sylvestris and P. abies were planted into a full-factorial experiment consisting of randomly assigned plant functional group (moss) removal in combination with passive warming (open-top chambers [OTCs]) along a post-fire chronosequence. Each seedling’s survival and growth had been surveyed over a period of three years (not as part of this thesis). At the end of the experiment, growth assessment in terms of biomass determination was done, by harvesting selected individuals. Growth has been found to be species-specific but without evidence of a direct or interactive warming effect. The survival analysis highlights that mosses promoted a positive warming effect on survival in the young and intermediate successional stages regardless of seedling species. In the old successional stage warming reduced survival regardless of moss presence explicitly for B. pubescens and P. sylvestris. If, as anticipated, climate change induces a shift toward younger forest stands by altering the fire frequency and climate warms, moss cover can therefore become a critical factor for seedling survival in the boreal forest.
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Anderson, Mrema Frank. "Abiotic and biotic factors influencing the performance of Leucaena leucocephala and Newtonia buchananii trees in Tanzania /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6313-0.pdf.
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Boivin, Joseph R. "Growth, nutrient dynamics, and outplanting performance of Picea mariana (Mill.) B.S.P. seedlings in response to fertilization during the hardening period." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58681.pdf.
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Bohl, Kerry. "An investigation of the factors leading to invasion success of non-native plants using a system of native, introduced non-invasive, and invasive Eugenia congeners in Florida." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4442.
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The overwhelming majority of plant species introduced into a new range never become invasive. Consequently, identification of factors allowing the small fraction of successful invaders to naturalize, increase in abundance, and displace resident species continues to be a key area of research in invasion biology. Of the considerable number of hypotheses that have been proposed to resolve why some plant species become noxious pests, the enemy release hypothesis (ERH) is one of the most commonly cited. The ERH maintains that invasive plants succeed in a new range because they are no longer regulated by their coevolved natural enemies, and this reduction in enemy pressure imparts a competitive advantage over native species, which continue to be negatively impacted by top-down processes. Alternatively, the ability of invasive plant species to outperform their counterparts, rather than escape from enemies, may be key in conferring invasion success. The importance of preadapted traits and release from natural enemies in successful invasion remains unclear, likely owing to a lack of empirical studies comparing their effects on relative performance and population growth of closely related species that differ in origin and invasiveness. A system of co-occurring native, introduced non-invasive, and invasive Eugenia congeners exists in south Florida, providing an opportunity to address deficiencies in our understanding of plant invasions by investigating the factors leading to invasion success for Eugenia uniflora. This approach is novel because very few studies have simultaneously incorporated both native and introduced non-invasive congeners into tests of these hypotheses, and no others have done so using this system of Eugenia congeners.
The first study in this dissertation tested the ERH using an insect herbivore exclusion experiment in the field to compare the effects of natural enemies on the performance and population growth of Eugenia uniflora and its native congeners. The results showed that E. uniflora sustained more herbivore damage than its native counterparts, and that the effects of herbivores were sufficient to have negative impacts on performance and population growth. In sum, these findings contradict the ERH. Surprisingly, the vast majority of damage to E. uniflora was caused by the recently introduced Sri Lankan weevil (Myllocerus undatus), with which it shares no coevolutionary history. The second study compared seedling performance among native, introduced non-invasive, and invasive Eugenia congeners to determine if the success of E. uniflora can be attributed to superior performance traits. Invasive E. uniflora was found to outperform its native and introduced non-invasive counterparts in a number of seedling traits, including emergence, growth, and survival, in spite of sustaining higher levels of herbivore damage in the field. This result was consistent across years and sites, suggesting that superior performance may be an important factor in invasion success by E. uniflora. The final experiment investigated the role of enemy release on performance of native, introduced non-invasive, and introduced invasive Eugenia seedlings using an insect herbivore exclusion experiment in the field. In this study, the invasive E. uniflora was again found to sustain more damage by foliar herbivores compared to its native and introduced non-invasive counterparts. However, in spite of higher levels of herbivore damage, E. uniflora continued to outperform its congeners in terms of stem growth, and its congeners did not outperform E. uniflora in any attribute. Insect herbivores negatively affected survival of all species, but were found to have little effect on growth. In combination, the results of these studies indicate that the ability of E. uniflora to outperform its native and introduced congeners at the seedling stage, and not release from insect herbivores, may contribute to its success as an invader. Additionally, E. uniflora exhibits relatively low resistance to herbivory in the new range, and instead may possess an ability to tolerate moderate levels of damage. The implications of this study are that enemy release may not be important in determining invasion success in some systems, and that the accumulation of new enemies may mitigate the effects of invasive plants over time. The paucity of studies investigating interactions among invasive plants and herbivores that share no coevolutionary history warrants further research. Finally, this system of Eugenia congeners provides valuable opportunities to test additional hypotheses and to further explore factors leading to invasion success.
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Dranski, João Alexandre Lopes. "Tigmomorfogênese na rustificação e sobrevivência em mudas de Pinus taeda L." Universidade Estadual do Oeste do Paraná, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1447.
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Previous issue date: 2013-03-04<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Thigmomorphogenesis is the adopted term to describe the growth response of plants to mechanical stimuli, naturally triggered by abiotic factors or artificially, by agroclimatic adverse event simulation. In the implantation of forest stands, such adversities limit of the seedlings establishment, and condition it to the recognize the limiting factor is the role in the hardening. It is speculated that the thigmomorphogenesis induced by stem bending become's more tolerant by forces exerted by the wind through the activation of mechanisms that alter the growth and accumulation of organic compounds. However, little is known if the employment of mechanical perturbations during seedlings hardening phase results in greater success in the implantation of forest stands. This present work aimed to evaluate morphophysiological alterations in Pinus taeda L. seedlings resulting from thigmomorphogenesis induced and its reflections about establishing in the field. For both, three experiments were conducted with the intention of quantify morphophysiological alterations resulting from stem bending and its reflections about establishing in the field; the partition and the buildup dry weight and carbon; and the correlation between lignin contente with field survival. P. taeda seedlings were produced by the nursery belonging to the company Sbaraini Agropecuária S.A., in Cascavel, PR. When reached the target size, were submitted to different intensities of stem bending during 60 days. At the end, were quantified morphophysiologic attributes, nutritionals, the dry weight and carbon partition between components, and lignin content. Additionally, the seedlings quality was measured by the root electrolyte leakage (REL). Posteriorly, part of the seedlings was planted in a commercial área of Pine monocropping in Cascavel, PR. Was quantitated by the survival, and increases of growth shoot at 90 and 360 days after planting. The increased intensity of the stem bendings reduced linearly of the stem height growth, the leaf area, resulting in the reduction in absolute growth rate and in the phosphorus content. Moderate intensities with up to 20 stem bending increased the secondary growth, the stem volume and the lignin content both in the root system how much aerial. The alteration in the primary and secondary growth was resulting of the carbon redistribution and of the dry weight accumulation in stem and in the root system, mostly in lateral roots, to the detriment of the leaf area reduction in terms of surface and dry matter. On the field, seedlings stimulated with that intensity showed higher survival and growth velocity, observed at 90 days after planting. After this period, he difference in growth velocity between seedlings stimulated or not has reduced, indicating acclimation of the seedlings unstimulated at the environment condition. There was correlation between the lignin content of the root system with the survival percentage at the 90 days, as well as the seedling quality measured by REL test proved to be predictive of field performance. Therefore, the application of 20 stem bendings applied during hardening of the P. taeda seedlings promoted greater success in implanting of the population in the experimental conditions analyzed.<br>Tigmomorfogênese é o termo adotado para descrever o crescimento dos vegetais em resposta ao estímulo mecânico, desencadeado naturalmente por fatores abióticos ou artificialmente, por simulação de eventos agroclimáticos adversos. Na implantação de povoamentos florestais, tais adversidades limitam o estabelecimento das mudas, e condicioná-las ao reconhecimento do fator limitante é o papel da rustificação. Especula-se que a tigmomorfogênese induzida por flexões caulinares tornam-as mais tolerantes às forças exercidas pelo vento, por meio da ativação de mecanismos que alteram o crescimento e o acúmulo de compostos orgânicos. Contudo, pouco se sabe se o emprego de perturbações mecânicas na fase de rustificação de mudas resulta em maior sucesso na implantação de povoamentos florestais. O presente trabalho objetivou avaliar as alterações morfofisiológicas em mudas de Pinus taeda L. resultantes da tigmomorfogênese induzida e seus reflexos sobre o estabelecimento no campo. Para tanto, três experimentos foram conduzidos com o intuito de: quantificar alterações morfofisiológicas resultantes de flexões caulinares e seus reflexos no desempenho das mudas a campo; a partição e o acúmulo de massa seca e carbono; e a correlação entre o teor de lignina com a sobrevivência no campo. Mudas de P. taeda foram produzidas pelo viveiro pertencente à empresa Sbaraini Agropecuária S.A., no município de Cascavel, PR. Quando atingiram altura maior que 15 cm, foram submetidas a diferentes intensidades de flexões caulinares durante 60 dias. Ao final, foram quantificados atributos morfofisiológicos, nutricionais, a partição de massa seca e carbono entre componentes da parte aérea (acículas, casca e cerne) e radicular (raízes laterais e pivotante), e o teor de lignina nas raízes e na parte aérea. Adicionalmente, a qualidade das mudas foi aferida pelo teste da perda eletrólitos de raízes (PER). Posteriormente, parte das mudas foi plantada em uma área comercial de monocultivo de Pinus em Cascavel, PR. Quantificou-se a sobrevivência, e os incrementos no crescimento aéreo aos 90 e 360 dias após o plantio. O aumento da intensidade de flexões caulinares reduziu linearmente o crescimento em altura, a área foliar, resultando em redução na taxa de crescimento absoluto e no teor de fósforo no sistema radicular e na parte aérea. Intensidades moderadas com até 20 flexões caulinares aumentou o crescimento secundário, o volume do caule e o teor de lignina tanto no sistema radicular quanto na parte aérea. A alteração no crescimento primário e secundário foi resultante da redistribuição de carbono e do acúmulo de massa seca no caule e no sistema radicular, principalmente em raízes laterais, em detrimento a redução de área foliar em termos de superfície e matéria seca. No campo, mudas estimuladas com 20 flexões caulinares externaram maior sobrevivência e velocidade de crescimento, observado aos 90 dias do plantio. Após este período, a diferença na velocidade de crescimento entre mudas estimuladas ou não reduziu, indicando aclimatação das mudas não estimuladas à condição do ambiente. Houve correlação entre o teor de lignina do sistema radicular com a porcentagem de sobrevivência aos 90 dias, assim como a qualidade da muda aferida pelo teste da PER mostrou ser preditivo ao desempenho no campo. Portanto, a aplicação de 20 flexões caulinares aplicadas na fase de rustificação de mudas de P. taeda promoveu maior sucesso na implantação do povoamento
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Akgul, Alper. "Performance of slash pine (Pinus elliottii Engelm.) containerized rooted cuttings and bare-root seedlings established on five planting dates in the flatlands of western Louisiana." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2230.
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The forest product industry is keenly interested in extending the normal planting season, as well as in the comparative field performance of standard nursery bare-root seedlings and containerized rooted cuttings. The effect of seasonal planting dates on survival, above and belowground biomass allocation, water relations, gas exchange attributes and foliar carbon isotope composition (δ13C) of two stock types of slash pine (Pinus elliottii Engelm.) were examined. Slash pine bare-root seedlings (BRS) and containerized rooted cuttings (CRC) were hand planted in September, November, January, March and April in three consecutive planting seasons (2000-2001, 2001-2002 and 2002-2003) on three sites with silt loam topsoils in southwestern Louisiana. First-year mean survival of CRC across all planting dates and sites was consistently high at 96 to 98%, whereas BRS survival was significantly (P < 0.0001) lower at 59 to 81% and highly variable among study sites and dates through three planting seasons. Generally, there was a negative relationship between soil moisture at the time of planting and first-year survival of BRS planted September through March in 2001-2002 and 2002-2003 planting seasons, whereas the opposite was observed only for BRS planted in April 2002 and 2003. Survival of CRC was affected very little by the variation in soil moisture. Containerized rooted cuttings had higher early above and belowground biomass, and height and diameter than did BRS. However, three years after planting the size differences between stock types disappeared or became negligible. Early size differences among trees planted September through March also decreased after three years, although September trees were tallest. Growth of the April-planted trees was poor compared to trees planted in other months. Late-planted April trees had higher δ13C values, and higher water-use efficiency in the first growing season compared to earlier planted trees. Differences in δ13C values among the planting dates disappeared in the second growing season. Net photosynthesis rates did not differ considerably between stock types or among planting dates in the second and third growing seasons. This study indicates that it is possible to extend the planting season to as early as September and as late as March by using CRC.
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Herendeen, Robert V. "Two-year Performance of Hybrid and Pure American Chestnut Castanea Dentata (Fagaceae) Seedlings and Benefit of Pisolithus Tinctorius (Sclerodermataceae) on Eastern Ohio Mine Spoil." Ohio : Ohio University, 2007. http://www.ohiolink.edu/etd/view.cgi?ohiou1174414428.
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Von, der Gonna Marc A. "First year performance and root egress of white spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Dougl.) seedlings in mechanically prepared and untreated planting sport in North Central British Columbia." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27347.
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Root zone temperature and root egress were studied during the first growing season on white spruce and lodgepole pine seedlings planted in various forms of mechanically prepared microsites. Mounded microsites had higher summer soil temperatures and greater diurnal ranges, at a depth of 10 cm, than the patch and control treatments. Mounded microsites, however, showed the greatest response to changes in weather and decreasing solar radiation inputs in the fall, being the first to record soil temperatures below freezing.
Seedlings planted in the deep mineral soil over inverted humus mounds created by the Ministry Mounder had significantly greater numbers of new roots greater than 1 cm long than did seedlings planted in patch and control treatments at 45 and 70 days after planting. Seedlings planted in other mound and plowing treatments had high to intermediate numbers of new roots. At 95 days after planting, seedlings planted on all mounded treatments generally had higher root area indices, root dry weights and total dry weights than did seedlings on other treatments. Variation in treatment results over the three spruce sites studied reflect differences in site conditions, primarily soil moisture regimes. High and fluctuating water tables negatively affected seedlings planted in patch and control treatments.<br>Forestry, Faculty of<br>Graduate
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Guindal, Estévez Guillermo. "Impacts of hydropower dams operations on plants : A greenhouse experiment on the response of germination and performance and survival of plant seedlings to direct and indirect effects of hydrological alterations resulting from hydropower dam operations." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-105157.
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This work helps increasing our general understanding of how plants behave under altered hydrological conditions which occur along rivers regulated by hydropower dams. Usually, natural-real environments are highly unpredictable. Consequently, research based on field data becomes challenging and results may contain uncertainty. Here, an experimental design in a greenhouse is developed. Several measured attributes of selected plant species related to germinability, performance and survival were used as indicators of the impact of watering treatments which mimic hydrological regime spilled through hydropower dams. Specifically, direct effect<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /><img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> of water availability changes, water fluctuation and water flooding, and indirect effect<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> through derived erosion, were tested. Results benefitted from indoors controlled conditions. They showed significant different responses depending on species and hydrological changes. In general, Helianthus annuus was slightly affected. It deal well flooding conditions, and was comparatively more affected by water fluctuation and stress. Carex and Filipendula species showed the highest sensitivities to flow. They hardly germinated under any water treatment (few germinations under flooding for Carex and few under water fluctuation for Filipendula) and performance was very low for germinates. Betula pubescens was in between. Contrarily to Helianthus, it was severely affected by flooding, and also for water fluctuation. It survived water stress better than Helianthus, but looked unhealthy. All species seeds but Helianthus were highly eroded. However, erosion resulting<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> from water fluctuation was relatively higher than from prolonged flooding. Differing responses are the result of morphological and physiological characteristics of the species which enable them to success under certain stressful conditions, such as water scarcity and anoxia. These results objectively inform about tolerance limits of selected species to key hydrological conditions and are useful for riparian areas management and environmental flows designs.
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Embaye, Kassahun. "Ecological aspects and resource management of bamboo forests in Ethiopia /." Uppsala : Dept. of Short Rotation Forestry, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s273.pdf.
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Bertoncello, Ricardo. "Restauração ecológica e processos estruturadores de comunidades vegetais." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-28092016-102207/.
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Interações interespecíficas são consideradas importantes forças estruturadoras da vegetação. Enquanto a competição aparentemente prevalece em ambientes com menor estresse abiótico, a facilitação tende a aumentar em importância em ambientes de maior estresse. Consequentemente, é esperado que a facilitação desempenhe um papel importante em áreas tropicais degradadas, nas quais as condições abióticas, envolvendo altos níveis de irradiação, temperatura e evapotranspiração, são muito distintas das condições ótimas para a maioria das espécies florestais. Além disso, face à complexidade dos processos estruturadores de comunidades florestais tropicais altamente diversas, os ecólogos têm percebido a necessidade de simplificação. Um caminho promissor para isso é por meio do uso de características funcionais, que podem ser medidas para qualquer espécie e comparadas em diferentes sistemas e locais. No entanto, em áreas degradadas ainda é incerta a relação entre as características funcionais e o desempenho das espécies. Neste contexto, planejamos um projeto de restauração na planície costeira do sudeste brasileiro para comparar o crescimento e a sobrevivência de mudas de árvores plantadas em diferentes densidades (sistema isolado ou sistema agregado) em um experimento fatorial com adição de nutrientes. No primeiro capítulo analisamos a sobrevivência, altura, diâmetro ao nível do solo e projeção da copa de 4.132 mudas de 19 espécies de diferentes classificações sucessionais, durante um período de 18 meses. Usamos modelos de efeitos mistos para analisar a relação entre o desempenho de espécies e os tratamentos e selecionamos os melhores modelos utilizando o critério de informação de Akaike (AIC). Verificamos uma maior sobrevivência nos sistemas agregados para as espécies não-pioneiras, indicando o predomínio do processo de facilitação. Em contrapartida, constatamos um menor crescimento em diâmetro nos sistema de plantio agregado, indicando o predomínio de competição. A adição de nutrientes não afetou a sobrevivência nos sistemas agregados, mas, surpreendentemente, teve um efeito negativo sobre as plantas isoladas. Além disso, a adição de nutrientes teve um efeito positivo sobre crescimento, diâmetro e projeção da copa nos sistemas de plantio agregado (indicando a redução da competição), especialmente para espécies pioneiras. Uma vez que o estabelecimento de espécies não-pioneiras em áreas degradadas pode ser bastante difícil, a facilitação para a sobrevivência dessas espécies em sistemas agregados pode ser utilizada como instrumento para melhorar os modelos de restauração. No segundo capítulo utilizamos algumas características funcionais que são facilmente mensuráveis para investigar sua relação com o crescimento e sobrevivência das mudas. Além disso, testamos o efeito das interações interespecíficas na relação das características funcionais com o desempenho das plantas. Para espécies pioneiras, uma maior área foliar específica (SLA - Specific leaf area), foi relacionada com uma maior taxa de sobrevivência. Entretanto, ao considerarmos as relações interespecíficas (sistemas agregados), maior SLA foi relacionada com uma menor taxa de sobrevivência. Em geral, as características funcionais explicaram apenas parcialmente o desempenho de mudas no contexto de restauração de áreas degradadas. Nosso trabalho contribuiu para a discussão sobre o potencial da aplicação prática da abordagem funcional na escolha das espécies para a recuperação de áreas degradadas. O caráter manipulativo da restauração ecológica baseada no plantio de mudas amplia as perspectivas para implementar experimentos que visem testar novas hipóteses em ecologia e refinar modelos de restauração<br>Interspecific interactions are considered to be important structuring forces in early successional vegetation. Whereas competition seems to prevail in less severe environments, facilitation tends to increase in importance in harsh environments. Hence, facilitation is expected to play an important role in degraded tropical areas with high irradiance, heat loads, and evapotranspiration, where conditions are far from optimum for most forest species. Moreover, in order to understand complex structuring process of high diverse tropical forests, ecologists have realized the need for simplification. A promising way to do that is through the use of functional traits, which can be measured for any species and compared in different systems and different locations around the world. However, in these conditions, little is known about the role of species interaction on the relation of functional traits and species performance. In this scenario, we planned a restoration project on the southeastern Brazilian coastal plain to compare growth and survival of tree seedlings planted at two densities (isolated or aggregated) in a factorial experiment with nutrient addition. In the first chapter we analyzed survival, height, ground level diameter, and crown projection of 4,132 saplings from 19 species that ranged along a successional gradient, over an 18-month period. We used mixed-effect models to analyze the relationship between species performance and treatments, and Akaike\'s information criterion (AIC) to select the models. The best model showed higher survival in aggregated plantations (indicating facilitation) for non-pioneer species. In contrast, we found lower diameter growth in aggregated plantation (indicating competition). Fertilizer addition did not affect survival in clusters, but, surprisingly, it had a negative effect on isolated plants of both pioneer and non-pioneer species. On the other hand, fertilizer addition had a positive effect on diameter and crown projection growth in aggregated plantations (reducing competition), especially for pioneer species. Thus, whether facilitation or competition was the predominant interaction depended on the response analyzed. We concluded that, as establishment of non-pioneer species in disturbed sites can be challenging, restoration designs could take advantage of higher survival rates in clusters and use resource addition to ameliorate growth and decrease competition for limited resources. In the second chapter we used the core simple-measurable traits to investigate whether functional traits were related to growth and survival and whether there was a difference in the effect of the functional traits on plant performance of isolated individuals or of individuals subjected to interaction with neighbors. Our main findings were that for pioneer species, the greater the specific leaf areas (SLA), the greater the survival rates, but, under aggregated conditions, the greater the SLA the lower the survival rates. However, functional traits only partially explained saplings performance in a restoration context and more research is needed to understand its role in predicting seedlings outcomes, especially considering the potential applicability of this methodological approach. The manipulative character of ecological restoration broadens perspectives to use experiments to generate and test new hypotheses in ecology and to refine restoration models
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Wang, Tsong-Ruey, and 王聰瑞. "Effects of nursery fertilization before out-planting on seedling field performances of four native species in Taiwan." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/22942032750846708700.
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碩士<br>國立臺灣大學<br>森林學研究所<br>87<br>The objective of this study was to examine the effects of fertilization loading on the seedling field performances of Formosan michelia 〔Michelia compressa (Maxim) Sargent〕, Taiwan incense cedar 〔Calocedrus formosana (Florin) Florin〕,Taiwan red cypress 〔Chamaecyparis formosensis Matsum〕, and Taiwania 〔Taiwania cryptomerioides Hay.〕. The experiment consisted of five treatments, namely, no fertilization (the control group), nursery fertilization of seedlings 10, 20 and 30 days before out-planting, and fertilization at the time of planting.
The results showed that nursery fertilization during the seedling dormancy period did not significantly affect shoot size in the nursery but was related to increased root-shoot ratio and nutrient status of seedlings, and hence improved the quality of seedlings. Among the three in nursery fertilization treatments, the best timing for fertilization was 20-30 days before out-planting. They did not only significantly increase the nitrogen concentration of seedlings, but also effectively enhance root growth potential of seedlings.
Four species of seedlings were outplanted to determine differences in field performance due to fertilization treaments. Formosan michelia and Taiwan incense cedar seedlings were out-planted on the U-Lai plot and Taiwan red cypress and Taiwania seedlings on the Her-Sheh plot, respectively. After one growing season in the field, nursery fertilization before out-planting increased survival of Taiwan incense cedar, Taiwan red cypress and Taiwania, while fertilization at out-planting had no effect on survival. In addition, fertilization prior to planting improved the nutrient status of seedlings so that initial growth after field planting of Formosan michelia, Taiwan incense cedar and Taiwan red cypress was increased. But fertilization at the time of planting had only little effect on for growth.
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Hung, Ching-chung, and 洪景鐘. "Simulation Based Performance Analysis of Automatic Vegetable Seedling Production." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/51104858618631990573.
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碩士<br>國立臺灣大學<br>農業機械工程學系研究所<br>85<br>This study is a computer simulation based performance analysis of automatic
vegetable seedling production. The analysis includes three systems of a
typical vegetable nursery. There are seeding system, transportation system
and the nursery system. The simulation program of the study was written in
AweSim!. In addition, the computer software, ExpertFit was used to obtain
fitting function for each procedure time in the simulation program.
Furthermore, the economic efficacy, including the cost and the ROI(return
on investment) of the typical vegetable nursery, is assessed in the study.
The simulation shows the results as follows. In the seeding system, the
labor utilization is under 50%, and the production rate is 175 trays per
hour; by using an improvement plan, the labor utilization will become 70% and
the production rate will increase to 240 trays per hour. In the process of
the transporting seedlings, it normally takes 29 minutes to move 500 trays
into the first greenhouse; by using an improvement plan, the working time
decrease by an amount of 30%. More over, it takes 73 minutes to move out
240 trays fromthe 20th greenhouse by using large boxes; the labor utilization
will increase from 36% to 60% and the working time will decrease 38% through
a suggested improvement plan.
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Huang, Shi Xin, and 黃世欣. "Design and performance analyses of grippers for seedling transplanting." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/42112516029690019393.
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Tsai, Hsin-hung, and 蔡信宏. "THE SYSTEM DYNAMICS MODEL OF ORCHID TISSUE CULTURE OF THE OPTIMUM SEEDLING PERFORMANCE TARGEST." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29350726621543678277.
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碩士<br>南華大學<br>企業管理系管理科學碩博士班<br>98<br>Phalaenopsis in Taiwan, is an early taste cultivation by private industry, after decades of breeding accumulation, the commercial varieties have reached a thousand, Taiwan in the international arena is the main origin of the one orchids. Taiwan''s orchid tissue culture in the face of the industry on how to cultivate the species Pingmiao out the best performance to set objectives and goals through the optimal performance, a view to reducing the gap between individual performance pressure, thereby increasing organizational revenues.
In this study, through system dynamics of the research methods to explore the relationship between the above-mentioned. System dynamic simulation results showed that performance goals set high and low for an individual job performance gap between the pressure and the actual revenues are greater differences, if the set of appropriate performance objectives, can improve proficiency personnel to operate and thus can be used to improve Pingmiao the rate of increase in the actual revenue the organization.
In this study, carried out the software Vensim model construction, this method is applied to simulate the dynamic behavior of the study, unlike conventional static social science research methods, among the variables through the system, dynamic simulation, and based on simulation analysis of the data, providing optimal decision management recommendations to reduce management operating costs, thereby improving corporate net income.
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Chen, Ming-Nan, and 陳明男. "Photosynthetic Performance of Four Podocarpus Species Seedlings Cultivated under Low Light Conditions." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/tsexd6.
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博士<br>國立中興大學<br>森林學系所<br>104<br>The purpose of this study is to observe and compare the photosynthetic performance of four Podocarpus species seedlings, including Podocarpus nakaii, P. fasciculus, P. costalis, and P. macrophyllus. The comparison was completed using functional broad leaves distributed at different elevations and regions, and cultivated under a 5% relative light intensity environment. To determine the differences between species, various measurements were complete; including through gas exchange and chlorophyll fluorescence characteristics, PSⅡ efficiency at different altitudes, as well as the photosynthetic induction during short-term intermittent illumination, from an ecological physiology stand point to understand their distribution.
The results show that the four Podocarpus seedlings cultivated under low light conditions have shade-tolerant characteristics, and are suitable for growing in shade. The PSⅡ photochemical efficiency of P. nakaii distributed in subtropical low altitude was lower than that of the other three species and was easily effected by temperatures below 10℃. Photosynthetic rate of P. fasciculus distributed in subtropical medium altitude was higher as the high level of predawn Fv/Fm could still be maintained at approximately 0℃. In addition, ETR and NPQ of P. fasciculus upon lightfleck induction were higher than that of the other three species, suggesting that its photosynthetic apparatus can adapt to temperatures below 10℃. Photochemical capacity and photosynthetic rate of P. costalis distributed in tropical coast were higher, but its non-photochemical capacity was lower than that of other species, creating serious photoinhibition when faced with temperatures below 10℃, as well as damage to its photosynthetic apparatus. The photosynthetic property of P. macrophyllus distributed in temperate to tropical regions is similar to that of P. fasciculus, and its photosynthetic performance in sub-10℃ conditions is also similar to that of P. fasciculus. Photosynthetic performance of the four species were induced by lightfleck and exposure to temperatures below 10℃. There was increasing DEPS during winter, but the photoprotection developed by NPQ needed more minutes. Photosynthetic rate of the four species were not limited by stomatal factors. The key to survival for these species is to protect their photosynthetic apparatus using non-photochemical quenching and effectively photosynthesize under low temperature conditions.
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Kostamo, Markku J. "Performance of interior spruce seedlings planted under dry soil and climatic regimes." Thesis, 1997. http://hdl.handle.net/2429/6409.
Full textAbstract:
A soil water balance model was used in a retrospective study of the survival and performance of short-day treated interior spruce seedlings, operationally planted in the Prince George region under dry soil and climatic regimes in July and August, 1994. The soil water balance model has potential to be used in operational forestry as a tool in managing plantation sites that are susceptible to drought. Comparison of modeled and measured soil water content indicated that the model is able to predict soil moisture accurately if applied to sites where model assumptions are met. The model should be a good predictor of soil water content between early May and mid August for the Prince George region. A linear regression model was developed predicting seedling performance by soil moisture. The relationship between a seedling performance index and mean ϒm (soil matric potential) for 30 days following planting is strong, r²= 0.75. The best predictor of a root variable from above ground morphological measurements was found to involve a volume surrogate (caliper² x height) as the independent variable and dry root mass as the dependent variable, r² = 0.50. Site characteristics were found to be a good predictor of seedling survival, r²2 = 0.64. An additional seedling study showed that percent survival has a strong relationship with the modelled mean ϒ for 30 days following planting. Survival decreases substantially below a mean ϒm of -0.2 MPa.
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Khan, Shafiqur Rehman. "Effects of shade on performance and chlorophyll fluorescence of four Pacific Northwest seedling conifer species /." 1995. http://hdl.handle.net/1957/10895.
Full text
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Hutten, Martin A. B. "Performance of Pinus ponderosa seedlings in clearcuts, patch cuts and undisturbed forests on lavas /." 1998. http://hdl.handle.net/1957/10873.
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Liu, En-U., and 劉恩妤. "The performance of germination and seedling growth of Leucaena leucocephala (Lam.) and indigenous trees species in drought environment." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76429212232319852423.
Full textAbstract:
博士<br>國立中興大學<br>森林學系所<br>103<br>This study compared the desiccation tolerance of exotic Leucaena leucocephala Lam. and indigenous Acacia confusa Merr., Pongamia pinnata L., Scaevola hainanensis Hance, Terminalia catappa L. and Bischofia javanica Blume. The desiccation tolerance of seedlings is crucial for growth and colonization of species under the increasing trend of extreme rainfall frequency and the yearly non-rainy day in Taiwan. The result indicated that nitrogen limitation influenced the morphological, physiological and biochemical performance in response to desiccation stress. T. catappa and B. javanica with lowest nitrogen content in leaf showed a longer leaf life span (plants maintained the leaf mass ratio and leaf area ratio) under experimental drought conditions in comparison with nitrogen-fixing species (L. leucocephala, A. confusa and P. pinnata). The morphological adjustment difference related to leaf-longevity also reflected in their photo-protective mechanism. T. catappa and B. javanica induced superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) antioxidant enzyme activity and increased non-photochemical quenching under moderate (soil water potential 0.32 ~ -0.99 MPa) and serious (-1.26 ~ -1.88 MPa) dry soil in contrast to the decrease of photo-protective mechanism of species with a shorter leaf life-span (L. leucocephala, A. confusa and P. pinnata). The trade-off between leaf turnover and biochemical influenced the allocation of biomass. T. catappa and B. javanica with longer leaf life span had the significantly lower root, stem and whole plant biomass than species with a shorter leaf life-span (L. leucocephala, A. confusa and P. pinnata) under serious dry soil after long term period (105 days). Moreover, species with lower whole-plant nitrogen content (S. hainanensis, T. catappa and B. javanica) prefer allocation of nitrogen to root and stem rather than to leaf, and it coincided with the lower C/N ratio and whole plant biomass under serious dry soil than species with higher whole-plant nitrogen content (L. leucocephala, A. confusa and P. pinnata). Therefore, species with low nitrogen content are not suitable for growth in long term dry soil. In the seedling stage, L. leucocephala and its common indigenous congener A. confusa was most desiccation-tolerant among six experimental species in long term dry environment (soil water potential -0.32~ -1.88 MPa). In order to compare further the ability of L. leucoephala and A. confuse to colonize habitats in dry soil, we investigated the desiccation tolerance of imbibed seeds of both species. The result indicated that embryonic axis protruded from L. leucocephala and A. confusa seed coats in coincidence with the transition from desiccation tolerance to intolerance.
The loss of desiccation tolerance in the embryonic axis of L. leucocephala and A. confusa upon the protrusion of embryonic axis was resulted from the degradation of raffinose and the slight increase of sucrose and monosaccharides. Moreover, seeds of L. leucocephala were more tolerant to desiccation than A. confusa after the protrusion of embryonic axis at various moisture contents. The result suggested that in the germinated stage L. leucocephala with superior desiccation tolerance will gain an advantage over their indigenous congener A. confusa for setting up population.
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Huang, Chun-Che, and 黃群哲. "Effects of Nitrogen, Phosphorus, Potassium Concentration, and Nitrogen Form on Growth of Plug Seedling and Subsequent Flowering Performance in Eustoma." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/74541485485429878701.
Full textAbstract:
碩士<br>國立臺灣大學<br>園藝暨景觀學系<br>101<br>Lisianthus [Eustoma grandiflorum (Raf.) Shinn.] is an important cut flower for export trade in Taiwan. Market demand has been increasing with increasing planting area and production. However, nutrition management during plug production for Eustoma has not been well established. This study aimed to determine the effects of nitrogen (N), phosphorus (P), and potassium (K) concentration, and nitrogen form of nutrient solution during plug production on seedling growth at 25/20oC and subsequent plant growth and flowering performance of Eustoma ‘Claris Pink’, ‘Rin’, and ‘Ceremony Blue Flash’ grown in summer and winter.
Johnson’s solution containing 4-24 and 4-36 mM N were weekly applied from cotyledon fully expanded to the third leaf pair stage during summer and winter, respectively. Seedlings fertilized with 16-20 mM N took shorter time from treatment to the first, second, and third leaf pairs expanded. Seedlings received 24-36 mM N did not exhibit faster growth, while those fertilized with 4-12 mM N grow slower. Whole plant net photosynthesis rate (Pn), increased with increasing N concentretion from 4 to 20-24 mM, and further increased N at 28-36 mM did not increase Pn. Seedlings fertilized with 4-8 mM N had significant lower Pn. Leaf Fv/Fm value increased from 0.67-0.76 to 0.80-0.82 when N concentration increased from 4 to 16-20 mM. Leaf area, whole plant, shoot, and root dry weight increased with increasing N concentration from 4 to 20-24 mM. Tissue N concentration increased with increasing solution N concentration. Tissue P, K, calcium (Ca), and magnesium (Mg) concentration decreased with increasing solution N concentration from 4 to 12 mM, but tissue P, K, Ca, and Mg did not decrease with higher solution N concentration (16-36 mM). After transplanting, plnats took longer time to bolt and flower when seedlings received 4-8 mM N, as compared with other treatments. Time to flowering and harvest was earlier when seedlings fertilized with 20-28 mM N.
Seedlings were fertilized weekly with Johnson’s solution containing 20 mM N in 0:100, 25:75, 50:50, 75:25, and 100:0 of NH4+ to NO3－ ratio. Medium EC increased and pH decreased with increasing NH4+ ratio. Pn, root activity, leaf area, and whole plant, shoot, and root dw increased with increasing NH4+ ratio. After transplanting, plants bolted earlier and had longer stem when seedlings fertilized with 50% or higher NH4+ as N source.
Seedlings were fertilized weekly with Johnson’s solution containing 0-2.5 and 0-2.0 mM P during summer and winter, respectively. Pn increased when P concentration increased from 0 to 1.0 mM, but decreased when P concentration increased to 2 mM. Leaf Fv/Fm value (0.8) did not differ between treatments, while those fertilized with 0 mM P, had the lowest Fv/Fm value. Seedlings fertilized with 2 mM P had the lowest root activity. Total leaf number, leaf area, and dry weight increased when P concentration increased from 0 to 1.0 mM, but decreased when P concentration increased to 2.0-2.5 mM. Tissue P concentration increased with increasing solution P concentration. Tissue N, K, Ca, and Mg concentration slightly increased when solution P concentration increased from 0 to 0.125-0.25 mM, but did not change significantly with further increases in P concentration. Plants took longer to flower when seedlings were fertilized with 0-0.25 mM P and some plants rosetted in summer when plug seedlings were fertilized without P. Flowering performance was not affected in plants when fertilized with 0.5-2.5 mM P during plug stage.
Seedlings were fertilized weekly with Johnson’s solution containing 0-10 mM K during summer and winter, respectively. Solution K concentration did not affect Pn and leaf Fv/Fm value. Tissue K concentration increased with increasing solution K concentration. Plants leaf area and total dry weight in ‘Claris Pink’ increased with increasing K concentretion from 0 to 4 mM, and further increased K to 10 mM did not increase growth in summer. Solution K concentration did not affect growth of ‘Rin’ and ‘Ceremony Blue Flash’ grown in summer. ‘Claris Pink’ and ‘Ceremony Blue Flash’ had higher leaf area and total dry weight when received 0-4 mM K during plug stage in winter High K (8-10 mM) treatments during plug stage reduced leaf area and total dry weight in plants grown in winter. Solution K concentration during plug stage did not affect growth of ‘Rin’ in winter. Flowering performance was not affected in plants when fertilized with 0-10 mM K during plug stage.
From the results as shown above, Eustoma seedlings of tested cultivars should be fertilized with Johnson’s solution containing 24-28 mM N with more than 50% NH4-N, 0.5-1.0 mM P, and 4-6 mM K weekly from cotyledon fully expanded to the third leaf pair expanded.
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Lin, Chin-lung, and 林進龍. "Growth Performances of Planting Seedlings of Taiwan Cypress under Canopy of Taiwan Cypress Forest in Chi lan-Shan." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/07851079329609036732.
Full textAbstract:
碩士<br>國立宜蘭大學<br>自然資源學系碩士班<br>95<br>Yellow cypress (Chamaecyparis obtusa var. formosana) and red cypress（Chamaecyparis formosensis）were dominant tree in cloud forest zone located Chilanshan area of Northestern Taiwan. Partial snag and dead-fall cypress tree were removed in some natural cypress forests by The Forest Conservation Administration for processing cypress resources conservation and regeneration option. This study focused on growth adaptability of cypress saplings under canopy environment after the removal work.
The study site was set up in the nature forest after remove treatment on line 130 forest road in Chilanshan. The canopy gap dynamic was stability after treatment in the early phase but the gap patch show more clumpy during 6-7years. The mechanism may be by typhoon disturbance. With stand visualization system program（SVS）, the canopy vertical structure of the forest show that main canopy story were composed of yellow cypress dominantly, subcanopy were hardwoods in the site. For exploring the adaptation strategy of these 2 cypress species at sapling stage under diversity of canopy condition, experiment was designed with 2yrth planting seedlings of yellow and red cypress as sapling stage under 3 canopy closure degree (weak, medium, strong, using spherical densitometer) plot site. We measured and compared mortality and growth performance of 2 cypress species stock in 9 years after planted.
Results show mortality rate of red cypress higher than yellow cypress under strong canopy closure at initial plantation stage, but lower under weak canopy, that expressed yellow cypress have more shade tolerant than red cypress. After 4 years, the mortality of the 2 cypress species were higher under weak closure, also, found much seedlings destroyed by rodents under open canopy condition.
The growth performance (height, diameter) of red cypress were better than yellow cypress under all canopy conditions during observation time. Annual growth of both cypress seedlings were litter under closure than open canopy, and growth difference of yellow cypress were significant than red cypress among canopy conditions. Growth rate of seedlings under open canopy were higher at initial time, and red cypress was better than yellow cypress. But growth rate declined as seedling develop, and no significant difference among species and canopy conditions. We also found the tendency that yellow cypress grew well under closure canopy after 8yrth. Seedling sturdiness quotient of red cypress were higher than yellow cypress, especially under closure canopy, that show light requirement of red cypress much than yellow cypress.
From mortality and growth expression at sapling stage under different canopy condition, We supported the hypothesis of adaptation strategy that red cypress was shade avoidance type and yellow cypress was shade tolerance type.
40
Gleason, John F. "Fertilization of 2-0 ponderosa pine seedlings in the nursery and field : morphology, physiology, and field performance /." 1988. http://hdl.handle.net/1957/13585.
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Kalibbala, Faith Nandawula. "The performance of the seed feeding bruchid beetle Sulcobruchus subsuturalis (Pic) (Cleoptera: Bruchidae) in the biological control of Caesalpinia decapetala (Roth) Alston (Fabaceae) an invasive weed in South Africa." Thesis, 2009. http://hdl.handle.net/10539/6785.
Full textAbstract:
The release of the seed eating beetle Sulcobruchus subsuturalis for biological control of
Caesalpinia decapetala in South Africa has been ongoing since 2000. This is the first
post release evaluation of the efficacy of the agent against the weed. The study assessed
the phenology of C. decapetala and S. subsuturalis at two sites and included determining
the establishment of the beetle on the target weed at 25 study sites. In addition, the effects
of S. subsuturalis on seed densities as well as seed germination and seedling recruitment
were examined. Furthermore predation by native ants and attacks by native parasitoids
were also examined at two release sites. Mature filled pods were available on the tree
from September (spring) to March (summer) when the beetle is expected to be
reproductively active. The majority of beetle releases by Working for water took place in
summer. However the proportion of beetle infested seeds, which were only recovered
inside pods in the tree canopy at study sites, was low (0 to 15.5%). Consequently high
seed densities and seedling recruitment were observed in the field. In the laboratory, S.
subsuturalis did not lay eggs on buried seeds, however seed infestation levels were
generally high. Only 8.3% of the seeds containing adults germinated and 6.3% emerged
into seedlings. Of the seeds containing larvae, only 14.6% germinated and 2.1% emerged
into seedlings. Thus far, S. subsuturalis has failed to maintain high populations on the
target weed, possibly due to egg predation by native ants (Crematogaster species,
Pheidole megacephala, Messor natalensis and Tetramorium avium) and attacks by native
parasitoids. Egg predation reached 100% within 10 days. Egg parasitism by unknown
parasitoids ranged between 80 and 93.1% in Limpopo. The parasitic wasp Dinarmus
altifrons was recovered once developing inside a C. decapetala seed infested with S.
subsuturalis. Further investigations regarding attacks by indigenous parasitoids on S.
subsuturalis are required to determine the extent of this problem. Meanwhile releases of
S. subsuturalis against C. decapetala should continue. However release efforts need to be
improved by (a) using inundative rather than inoculative releases (b) Releasing every
year between September and March (summer) and (c) involving land owners, farmers
and nature reserve authorities in release activities. Ultimately an additional agent should
be sought for release against C. decapetala as the weed may not be the preferred host for
S. subsuturalis.
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Vera-Castillo, J. A. Gil. "The influence of antidesiccants on field performance and physiology of 2+0 ponderosa pine (Pinus ponderosa Dougl.) seedlings /." 1995. http://hdl.handle.net/1957/11205.
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Piechowski, Daniel [Verfasser]. "Reproductive ecology, seedling performance, and population structure of Parkia pendula in an Atlantic forest fragment in Northeastern Brazil / vorgelegt von Daniel Piechowski." 2007. http://d-nb.info/997414057/34.
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Yen, Lin, and 林巖. "Comparison of Growth Performances and Physiological Characteristics among Transgenic Plants, Tissue-Cultured Plantlets and Seedlings of Sweetgum (Liquidambar styraciflua L.)." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/84379464240626819692.
Full textAbstract:
碩士<br>國立臺灣大學<br>森林學系<br>84<br>The objectives of this study were to determine the differences
of sweetgum seedlings, tissue-cultured plantlets and transgenic
plants carrying the foreign O-methyltransferase (OMT) DNA in
growth performance and physiolocial characteristics. Based on
there determinations, the effect of regeneration pathway via
tissue culture method on growth traits and physiological
characteristics and the alternation of plantlet quality would
be first verified. Secondly, whether or not the growth traits
and physiological characteristics of transgenic plants were
indirectly influenced by the transferred lignin-specific
OMT DNA would also be distinguished. Seedling, plantlets,
transgenic plants carrying the full lenght of aspen OMT cDNA
clone and transgenic plants carrying the antisense DNA fragment
of the aspen OMT gene, all derived from the same sweetgum
seedlot, were propagated and raised in vitro, and further
transplanted to the greenhouse. Growth traits and
physiological characteristics including height, diameter at
root collar, net photosynthesis, concentrations of chlorophyll
a and b, and total nitrogen in leaves, dry weights of leaf,
stem and root were measured among various plants at one and a
half months old in vitro and at 4, 6 and 8 monthsold after
transplanting to the greenhouse. Chlorophyll a:b ratio, shoot
and root(S/R) ratio and Diskson index were calculated.
45
ZHOU, WEN-NENG, and 周文能. "Study on the mycorrhizae of native vegetation and the performances of ectomycorrhizae inoculated with pine seedlings on coal mine spoils." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/19773319680263968333.
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Alzugaray, Oswald Patricio Javier. "Effects of fertilization at the time of planting on field performance of 1+1 Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings /." 2002. http://hdl.handle.net/1957/11014.
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Chen, Shuen-Ying, and 陳舜英. "Effects of Nitrogen Fertilizers and Light on the Morphological and Physiological Changes and Outplanting Performance of Three- cupule Tanoak (Pasania ternaticupula Hay.) Seedlings." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/34298663431439097662.
Full textAbstract:
碩士<br>國立臺灣大學<br>森林學系<br>85<br>This study investigated the changes in the morphology and
physiology of Pasania ternaticupula seedlings by treating
germinated seedlings continuously with different levels of
nitrogen fertilizers and light intensities, and examined the
outplanting performance of those nursery seedling stocks. The
results showed that height growth, collar diameter, dry weights
of shoots and roots, Dickson quality index, the numbers of
stomata per unit leaf area and ratio of chlorophyll a and b of
seedlings increased when the relative light intensity was
increased in the greenhouse. Relative light intensities of 26%
and 16% full daylight were more effective than a relative light
intensity of 4% full daylight. However, the increases of dry
weight of leaf, shoot-root ratio, leaf numbers, leaf area, leaf
area ratio, special leaf area and total chlorophyll content in
leaf were measured under a relative light intensity of 4% full
daylight and were significantly different as compared to a
relative light intensity of 26% full daylight. In the nitrogen
fertilizer experiment, growth height, collar diameter, dry
weight of seedling, leaf numbers, leaf area and ratio of
chlorophyll a and b of seedlings were increased following an
increase in nitrogen fertilizer quantity. The analysis of 20
amino acids from leaves revealed that there was no significant
difference in concentrations of these amino acids among the four
nitrogen fertilizer treatments. However, concentrations of each
of the 20 amino acids increased when light intensity decreased.
According to a correlation analysis, seedling growth after
outplanting was affected by both nitrogen fertilizers and light
intensities. Furthermore, correlation analysis between seedling
growth and parameters indicated that seedling growth was
positively correlated with the Dickson quality index, but
negatively correlated with special leaf area and tryptophan.
In summary, the treatments with relative light intensity of 26%
or 16% full daylight, and nitrogen concentrations of 300 or
400kg per ha had better seedling growth.
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Mare, Rorisang 'Maphoka. "Phytotron and field performance of Taro [Colocasia Esculenta (L.) Schott] landraces from Umbumbulu." Thesis, 2006. http://hdl.handle.net/10413/4122.
Full textAbstract:
The taro landraces that are most preferred by farmers from Umbumbulu, KwaZulu-Natal
were identified through focus group discussions with farmers. Farmers ranked taro
landraces on the basis of preference as determined by economic value, social
significance, ecological importance and food characteristics. Using pairwise ranking, the
farmers' preference of taro landraces across all locations was found to be in the following
order: Dumbe-dumbe, Mgingqeni, Pitshi and Dumbe-lomfula. Dumbe-dumbe was
identified as the currently actively cultivated taro whereas Mgingqeni was regarded as a
less desirable cultivated taro. Pitshi was regarded as an antiquated landrace and Dumbe-lomfula
was generally regarded as a taro type of no economic, social or food value that
grew on river banks as a wild species.
Glasshouse and field studies were conducted to determine the effects of temperature and
growing location [Pietermaritzburg (UKZN) and Umbumbulu] on emergence, plant
growth and yield of taro. Starch and mineral composition of taro corms were determined
in harvest-mature corms. Effects of three day/night temperature levels (22/12°C, 27/17°C
and 33/23°C) were examined on the growth of four taro landraces Dumbe-dumbe,
Mgingqeni, Pitshi and Dumbe-lomfula. Pitshi-omhlophe, an ecotype of Pitshi for which
there was a limited amount of planting material, was also included in the glasshouse
studies. The farmers stated that the normal growing season for the economically
important landraces, Dumbe-dumbe and Mgingqeni, was six months, but in this study
plants were grown in glasshouses for nine months, and in the field, for seven months
before the attainment of harvest maturity.
Emergence was determined daily for glasshouse experiment until all plants had emerged
and it was determined monthly for the field experiment. Leaf number, plant height and
leaf area were measured every month to determine growth and development, while
number of corms and fresh corm weight were used at harvest to determine yield. For all
landraces, time to emergence increased significantly with decrease in temperature from
33/23°C to 27/17°C, but it increased significantly for only Dumbe-dumbe and Mgingqeni
from 27/17°C to 22/12°C. Mgingqeni showed the shortest time to emergence, whereas,
Pitshi showed the longest delay in emergence. The locations were not significantly
different in emergence. Mgingqeni displayed the highest emergence in UKZN (91.4%),
whereas, Dumbe-dumbe displayed the highest emergence (95.5%) and Dumbe-lomfula
displayed the lowest emergence (55.9%) in Umbumbulu. Leaf number was highest for
Pitshi-omhlophe, in glasshouse experiment due to its tendency to produce multiple shoots
compared with the other landraces. Plant height increased with increase in temperature
for all landraces except for Pitshi, for which height decreased with an increase in
temperature. Leaf area was greatest for Dumbe-lomfula at all temperatures and lowest for
Pitshi at both 22/12°C and 27/17°C. Leaf number was highest for Mgingqeni and lowest
for Dumbe-lomfula at both sites, although it was significantly lower only for Dumbe-lomfula
in UKZN. Plant height and leaf area were significantly highest for Dumbe-lomfula
at both sites. The highest total number of corms per plant was shown by Pitshi-omhlophe
at 22/12°C. Total fresh corm weight was highest for Dumbe-lomfula at
27/17°C and lowest for Pitshi at 22/22°C. The field experiment results showed Pitshi and
Dumbe-lomfula with significantly higher total fresh corm weight in UKZN compared
with Umbumbulu.
Corms were analysed for mineral elements and starch. There were significant differences
in starch content between temperatures (P = 0.017) and taro landraces (P = 0.025). There
was also a significant interaction of temperatures and landrace (P = 0.002). Starch content
increased with temperature for all landraces except for Pitshi-omhlophe and Dumbe-lomfula
which showed a decrease at 27/17°C. There were significant differences in corm
mineral content between temperatures, locations and landraces (P < 005).
It is concluded that the chemical composition of taro corms is influenced by growth
temperature and the location (site) where the crop is grown. The results of this study also
indicated that taro plant growth is enhanced by high temperatures (33/23°C). High
temperatures are, however, associated with short leaf area duration and subsequently low
yield. The findings of this study may also be useful in determining taro quality for
processing.<br>Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
49
Nemakanga, Rendani. "Pepper and tomato seed performance in response to imbibition and dehydration." Thesis, 2005. http://hdl.handle.net/10413/4480.
Full textAbstract:
The International Seed Testing Association and the Association of Official
Seed analysts define seed vigour as the ability of a seed lot to perform during
the germination process and crop stand establishment under a wide range of
environmental conditions. There are many ways to determine seed vigour, but
few satisfy the requirements of being simple, inexpensive and reproducible,
among others, to permit the seed industry to adopt seed vigour as an indicator
of seed quality when they sell seeds. Hence, the standard germination test,
which is performed under uniform and favourable conditions, is generally used
to indicate seed quality when seeds are marketed. The objective of this study
was to determine the performance of tomato and pepper seeds in response to
pre-germination hydration and dehydration relative humidities (12%, 49% and
75% RH). Before hydration, seeds were hydrated at three temperatures
(10°C, 20°C and 30°C). Hydration was performed by imbibing pre-weighed
pepper ('Santarini' and 'California Wonder'), Chilli and tomato ('Heinz',
'Marondera' and 'Roma') seeds for 2 h in 10 ml of distilled H(2)0 per 100 seeds
at 10°C, 20°C and 30°C. Dehydration was performed by change in seed mass
determined during a 72-hour dehydration at 12%, 49% and 75% RH. Seed
performance in response to imbibition and dehydration was determined by
leakage of electrolytes from seeds during imbibition, laboratory germination
capacity and seedling emergence under simulated shadehouse nursery
conditions. A pot experiment was conducted to determine the effects of seed
treatments on yield. Seed mass increased by about 50% during the 2-hour of
hydration. Dehydration was hastened by decreasing the RH, and 12% RH
significantly (P < 0.05) reduced the post-imbibition seed moisture content
compared with 49% and 75% RH. The latter two relative humidities reduced
the seed moisture content to about 10% and 15%, respectively, for all
cultivars, irrespective of imbibition temperature. Low imbibition temperature
(10°C) significantly (P < 0.01) increased electrolyte leakage, compared with
high imbibition temperatures (20°C and 30°C), which were not significantly
different from each other. At all hydration temperatures, low RH (12%) caused
a significant (P < 0.01) decrease in seed germination whereas 49% RH and
75% RH apparently had a priming effect on seeds. There was no significant
difference between imbibition temperatures, with respect to seed germination,
but 100G caused a significant decrease in germination index, a measure of
seed vigour. Seedling emergence was significantly (P < 0.01) reduced by both
low imbibition temperature (10oG) and low dehydration relative humidity (12%
RH). The negative effects of low imbibition temperature and rapid dehydration
at 12% RH were also observed as stunted seedling growth.
Principal component analysis and linear regression were used to determine a
statistical model to predict seedling emergence from germination percentage.
The model predicted emergence consistently, but it overestimated it by about
2% to 3%. It is concluded that low imbibition temperature and rapid
dehydration can be used to simulate stress to determine seed performance in
pepper and tomato.<br>Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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Kupers, Stefan Jonathan. "The Soil Moisture Niche in a Moist Tropical Forest – A Demographic Approach." 2019. https://ul.qucosa.de/id/qucosa%3A37543.
Full textAbstract:
Water availability affects tree species performance and distributions in tropical forests. However, there are no studies that have measured detailed spatial variation in soil water availability within a tropical forest. This limits our understanding of how water availability shapes the demography and distributions of tree species within tropical forests. In this dissertation, I measured detailed spatial variation in soil water potential (SWP), the relevant measure of water availability for plant performance, in the seasonal tropical moist forest of the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama. In Paper 1, I mapped spatial variation in SWP across the 50-ha plot in various stages of the dry season using information on topography, soil type, dry season intensity and more. In Paper 2, I quantified the soil moisture niches of species in terms of demographic responses (growth and mortality) and species distributions. I related seedling growth and mortality responses to SWP of 62 species to their distributional centre along the SWP gradient, using data from 20 years of annual seedling censuses across 200 seedling census sites. I found that species that grew faster (slow) with increasing SWP were more common on wetter (drier) parts of the SWP gradient. Moreover, wet-distributed species grew faster on the wet side of the SWP gradient than dry-distributed species. Mortality was unrelated to species distributions but decreased strongly with seedling height. These findings indicate that species with a growth advantage with respect to SWP grow faster out of the vulnerable small size ranges, reducing their mortality in later seedling stages and thus shaping species distributions indirectly. This mechanism is a form of niche differentiation that contributes to species coexistence. In Paper 3, I related seedling growth and mortality responses to spatiotemporal variation in water availability with responses to light availability, another highly limiting resource in tropical forests. I found an interspecific trade-off in responses to shade versus inter-annual drought (dry season intensity): species that performed relatively well in the shade performed worse during more severe dry seasons and vice versa. This trade-off enables coexistence, because species are adapted to perform well under either shade or drought. In sum, water availability contributes to the maintenance of the high diversity of tropical forests through hydrological niche differentiation and a trade-off between performance in shade versus drought. Future work can use my SWP maps and species responses to SWP to identify the functional traits that underlie the species responses and improve Dynamic Global Vegetation Models. Finally, my work facilitates the prediction of future species composition, diversity and ecosystem functioning of tropical forests with shifts in rainfall patterns caused by climate
change.