Dissertations / Theses on the topic 'Seedling age'

In wheat, stem rust is known to rapidly evolve new virulence to resistance genes. While more than 50 stem rust resistance (Sr) loci have been identified in wheat, only a few remain effective, particularly against the highly virulent race Ug99 (TTKSK race) and a mixture of durum-specific races. An association mapping (AM) study based on 183 durum wheat accessions was utilized to identify resistance loci for stem rust response in Ethiopia over four seasons and artificial inoculation with Ug99 (TTKSK race) and a mixture of durum-specific races under field conditions as well as in greenhouse test at seedling stage under controlled conditions for resistance to four highly virulent stem rust races: TRTTF, TTTTF, (TTKSK (Ug99) and JRCQC. The panel was profiled with 1,253 SSR and DArT markers. Twelve QTL-tagging markers were significant (P < 0.05) across three to four seasons. The role of Sr13, Sr9, Sr14, Sr17, and Sr28 was confirmed. Thirteen significant markers were in regions with no Sr genes/QTLs. The results under controlled conditions showed that 15, 20, 19 and 19 chromosome regions harbored markers that showed significant effects for races TRTTF, TTTTF, TTKSK and JRCQC, respectively. These genomic regions showed marker R2 values ranging from 1.13 to 8.34, 1.92 to 17.64, 1.75 to 23.12 and 1.51 to 15.33% for races TRTTF, TTTTF, TTKSK and JRCQC, respectively. The study demonstrates that stem rust resistance in durum wheat is governed in part by shared loci and in part by race-specific ones. The QTLs identified in this study through AM will be useful in the marker-assisted development of durum wheat cultivars with durable stem rust resistance.

In wheat, stem rust is known to rapidly evolve new virulence to resistance genes. While more than 50 stem rust resistance (Sr) loci have been identified in wheat, only a few remain effective, particularly against the highly virulent race Ug99 (TTKSK race) and a mixture of durum-specific races. An association mapping (AM) study based on 183 durum wheat accessions was utilized to identify resistance loci for stem rust response in Ethiopia over four seasons and artificial inoculation with Ug99 (TTKSK race) and a mixture of durum-specific races under field conditions as well as in greenhouse test at seedling stage under controlled conditions for resistance to four highly virulent stem rust races: TRTTF, TTTTF, (TTKSK (Ug99) and JRCQC. The panel was profiled with 1,253 SSR and DArT markers. Twelve QTL-tagging markers were significant (P < 0.05) across three to four seasons. The role of Sr13, Sr9, Sr14, Sr17, and Sr28 was confirmed. Thirteen significant markers were in regions with no Sr genes/QTLs. The results under controlled conditions showed that 15, 20, 19 and 19 chromosome regions harbored markers that showed significant effects for races TRTTF, TTTTF, TTKSK and JRCQC, respectively. These genomic regions showed marker R2 values ranging from 1.13 to 8.34, 1.92 to 17.64, 1.75 to 23.12 and 1.51 to 15.33% for races TRTTF, TTTTF, TTKSK and JRCQC, respectively. The study demonstrates that stem rust resistance in durum wheat is governed in part by shared loci and in part by race-specific ones. The QTLs identified in this study through AM will be useful in the marker-assisted development of durum wheat cultivars with durable stem rust resistance.

Embryogenesis, germination and early phases of seedling growth represent critical phases in the plant life cycle and are probably the most important events in determining the success of an annual plant. A rapid and robust emergence positively influences the capacity of the plant to take advantage of the favourite environment and to compete with its neighbours. In the perspective of a more sustainable agriculture specific characters are envisaged for a crop seedling, such as the resistance to environmental critical abiotic as well as biotic factors. For these reasons key factors subtending plant developmental process and contributing to the achievement of a productive and robust plant have to be searched inside the genetic network that control embryo and seedling development. Among the different aspects affecting seedling development the two that will be analysed in this study play an important role also in the interplay with the environment. Hormones are endogenous signals governing seedling growth and architecture establishment but at the same time are able to induce plant response to environmental stress. Wax deposition is required for determining a correct embryo and seedling development, and provides, beside that, a protective barrier that plants produce in their early developmental phases to defend themselves from pathogens as well as from variation in environmental abiotic components, such as temperature and water availability. Here, we report the characterization of the mutants lilliputian 1-1 (lil1-1) and fused leaves 1-1 (fdl1-1), both ascribable to defective seedling (des) maize mutants. lilliputian 1-1 (lil1-1) is a monogenic recessive mutant of maize, isolated from an active Mutator (Mu) stock and attributed to the insertion of a Mutator1 element in the first exon of a the gene encoding the BR C-6 oxidase. The enzyme belongs to the superfamily of CYP85A proteins and catalyzes the final steps of brassinosteroid synthesis. lil1-1 mutant exhibits a reproducible phenotype consisting of a large primary root, extremely reduced stature and crinkly leaves. Recently, another dwarf mutant of maize impaired in the same brassinosteroid C-6 oxidase and showing a very similar phenotype of lil1-1 has been characterized and the corresponding gene was termed brasssinosteroid deficient 1 (brd1) Allelism between the two mutant alleles has been demonstrated in this work. Moreover, it has been observed that the exogenous application of brassinolide to the lil1 mutant seedlings resulted in a partial recovery of the lil1-1 phenotype. This observation is in agreement to what previously observed for brd1-m in maize and other Br-deficient mutants in Arabidopsis, rice and tomato. Differently from some of these mutants, i.e det2 of Arabidopsis, lil1 genotype does not influence the seed formation and development. It is evident that the comparison between homozygous lil1-1 mutant and Li11-1 wild-type seeds from the same segregating ear did not highlight any difference in weight. In addition, F2 progeny ears obtained from F1 heterozygous Lil11/lil1-1 or homozygous Lil1-1/Lil1-1 plants showed the same average kernel number and total kernel weight per ear and the average weight of single kernel. BRs are also involved in the modulation of stress responses. Water loss assays and measurement of gas exchange demonstrated that lil1-1 plants lost less water and maintained efficient gas exchange under drought stress for longer time than wild-type siblings. Our hypothesis is that lil1-1 mutant is more tolerant to drought stress because it is by default in a physiological water stress condition. A similar interpretation has been proposed to explain the behaviour of the det2 mutant in Arabidopsis that is deficient in a steroid reductase. The det2 mutant showed an enhanced resistance to general oxidative stress, correlated with a constitutive increase in superoxide dismutase (SOD) activity and increased transcript levels of the defence gene catalase (CAT). To confirm this hypothesis, other studies must be performed, among them the expression analysis of genes involved in dehydration stress. However, the hypothesis is at the moment supported by the observation that lil1-1 mutant plants show phenotypic traits that are generally present in plant subjected to water stress, i.e. inhibition of lateral root growth, reduction in leaf area and plant growth, enlarged leaf thickness and increased stomatal density. The fdl1-1 mutant, previously isolated in our laboratory, allowed the identification and functional analysis of a novel maize MYB gene. The fdl1-1 mutation was caused by an Enhancer/Suppressor (En/Spm) element insertion in the third exon of the sequence encoding ZmMYB94, a transcription factor of the R2R3-MYB subfamily. In this work, proof of gene identity was obtained using an RNAi approach and by the analysis of the mutant cDNA sequence. The first experiment ascertained the lesion in the third exon of the sequence encoding ZmMYB94. The second approach confirmed that the mutant transcript retains the En/Spm element. The fdl1-1 mutant phenotype is expressed at early stages of seedling development, from germination to the three-four leaves stage, causing a general delay in germination and seedling growth as well as phenotypic abnormalities. The main features of mutant plants are irregular coleoptile opening and the presence of regions of adhesion between the coleoptile and the first leaf and between the first and second leaves. A previous study showed that fusions could be attributable to the alterations in cuticle deposition and highlighted an irregular wax distribution on the mutant leaf surfaces. Phylogenetic analysis demonstrated that its closest Arabidopsis related genes, i.e. MYB30, MYB94 and MYB96 have all been implicated in the regulation of cuticular wax biosynthesis in Arabidopsis. To gain insight into the role exerted by ZmMYB94 a deeper characterization of cuticle components were therefore undertaken in this study by comparing mutant and wild-type tissues. We found a significant reduction of the amount of waxes in the mutant versus wild-type samples at earlier developmental stages. In particular, the production of C32 alcohols, which is the major compound of cuticular waxes in the maize seedling, resulted drastically reduced in the mutants and replaced by shorter chain alcohol (C26, C28 and C30) and alkane (C29). On this basis, we speculate that ZmMYB94 specifically affects the activity of enzymes involved in the elongation of long chain wax molecules at the C30—C32 step. In maize, some glossy mutants, i.e glossy 2 and glossy 4 show the same block in the long chain elongation. Thus, some of the subtending genes could be under the control of ZmMYB94. Contrary to fdl1-1, none of glossy mutant of maize so far characterized showed post-genital organ fusion. This difference could be due to a greater decrease (more than 90%) of epicuticular waxes observed in the fdl1-1 mutant than in glossy mutants. It is also conceivable that ZmMYB94 affects directly or indirectly the expression of a set of genes involved in the biosynthesis of very-long-fatty acids and the failure of multiple activities has caused a worsening of the phenotype. Alternatively, ZmMYB94 could regulate also some genes involved in the biosynthesis of other cutin components. Although only minor changes in the cutin load were observed in the fdl1-1 mutant, the affected components could be important for determining organ separation. Recent studies strongly support the idea that cuticular wax accumulation contributes to drought resistance. However, it is still not known in crops how wax related genes are regulated in response to drought. In our study, an increment of water loss in the mutant seedlings has been demonstrated and a correlation between the severity of the phenotype and the rate of water loss was revealed. Moreover, we found that the transcript level of ZmMYB94 increased in plant under drought stress condition. Similarly to AtMYB30, AtMYB94 and AtMYB96, which are considered positive regulators of wax biosynthesis during stress, it is conceivable that ZmMYB94 stimulates the activity of genes involved in cuticular waxes biosynthesis thus contributing to increase drought tolerance in the early phases of maize seedling growth. In conclusion, our study further indicate that the study of BR-related mutants and mutants impaired in cuticular waxes biosynthesis could be important for unravelling the molecular mechanisms underlying stress response in early developmental phases of cultivated plants and ultimately to identify new genetic tools of interest for their application in designing new breeding strategies.

Maize is one of the most important cultivated plants on a world scale, with a total production which exceeds one billion tonnes per year (FAOSTAT 2017). It is an important human food source in many parts of the world, but is also intensely exploited for biofuel and feed production. Furthermore, maize is also a model plant for research studies in the field of biology and genetics. For these reasons, maize is one of the most intensively studied crops, with the aim of improving its productivity, which in the USA has increased nearly five times since the 1940s. This dramatic yield improvement is due to the development and widespread use of new farming technologies. An important role was played by genetic improvement, with the use of highly productive maize hybrids and, more recently, biotechnology. However, the increases in annual productivity of maize and the other main crops exploited for food production seem to have reached a stall phase in recent years. It has been estimated that the world population will increase from 7.5 to 9.7 billion people by 2050. To meet the food needs of the increasing population, and to satisfy diets that will include more meat, according to the Food and Agricultural Organization (FAO), worldwide crop production will have to increase by 70%. It is a tough task, made even more difficult by the fact that the worldwide area of cultivable soil is decreasing as a consequence of increasing urbanization and climate change. To reach the target, new strategies are required, which will include multiple and integrated approaches, among them genetic improvement. One of the main challenges will be to develop new plant ideotypes that will combine the capability to tolerate biotic and abiotic stress with no reduction in yield. Within this perspective, the work carried out in this thesis project was aimed at understanding the molecular mechanisms involved in plant response to environmental factors. The work was organized in two parts, which are presented here in two different chapters. Both chapters are focused on genes that control plant development as well as plant- environment interactions. The first chapter deals with the study of the genetic regulation of cuticle deposition in maize. The cuticle is an important plant organ and constitutes the first barrier against many environmental stresses, including water deprivation and pathogen interaction. The cuticle is produced by epidermal cells and is composed of a complex array of long chain hydrocarbons, constantly deposed on the aerial surface for all the plant’s life. To investigate the cuticle biosynthesis process in maize, our strategy was based on the functional characterization of ZmMYB94, also known as fused leaves 1 (fdl1). This gene encodes a transcription factor of the R2R3-MYB subfamily, expressed in embryo, seedling and silk tissues. A mutant in this gene, referred to as fdl1-1, was available for this study. It originated from the insertion of an Enhancer/Suppressor (En/Spm) element in the third exon of the ZmMYB94 gene. The mutation has a pleiotropic effect on seedling development. The main features of fdl1-1 mutant plants are irregular coleoptile opening and the presence of regions of adhesion between the coleoptile and the first leaf and between the first and second leaves. Deeper studies of the fdl1-1 mutant, performed by electron microscopy analysis, showed that, in regions of organ adhesion, cuticle was absent and, on the epidermal surface, epicuticular wax deposition occurred irregularly. These observations led to the hypothesis that phenotypic alterations observed in the mutant seedlings may be attributable to defects in the cuticle-related biosynthetic pathways. To gain insight into the role of fdl1 in controlling cuticle formation, a large-scale RNA sequencing analysis was carried out in this work. By means of this approach, more than one thousand differentially expressed genes (DEGs) were found in the fdl1-1 mutant compared with the wild type seedling transcriptome. The analysis of single DEGs confirmed that fdl1 is involved in the regulation of the biosynthesis of both cuticle components, since genes for the cuticular waxes deposition as well as cutin biosynthesis were detected. In particular, five genes with a reduced expression level and one with an increased expression level in the fdl1-1 mutant encoded for enzymes involved in the Fatty acid elongation complex, the main source of basic compounds exploited in cutin and waxes biosynthesis. Furthermore, two genes found with a reduced expression level in the mutant were also involved in the cutin biosynthesis. Interesting sidelights on these two genes are available from the study of their orthologues in rice (OsONI3) and in Arabidopsis (AtEDA17). The knock-out mutant of ONI3 in rice shows a phenotype that is very similar to that of the fdl1-1 mutant in maize, with defects in cutin deposition and fusions between the coleoptile and the first leaves. Moreover, the knock-out mutant of EDA17 in Arabidopsis shows defects in cutin deposition and fusions between floral organs. Other two genes found differentially expressed in fdl1-1 encode for enzymes involved in epicuticular waxes biosynthesis, thus explaining the defects observed in fdl1-1 mutants. On the basis of these observations, we developed a model that explains the mode of action of fdl1 in controlling cuticle formation. Furthermore, the large-scale RNA sequencing analysis done in this study revealed a considerable number of genes differentially expressed in the fdl1-1 mutant that are involved in other important processes, such as plant clock regulation, plant pathogen interaction and hormone signalling. A deeper investigation of the role of these genes will be of help in elucidating the action of fdl1 in controlling different aspects of plant development. We also demonstrated in the present study that fdl1 is actively involved in the drought stress response in maize seedlings. Indeed, an expression analysis showed strong differences in the fdl1 transcript level in seedlings exposed to drought stress condition compared with seedlings grown in well-watered conditions. Indeed, in normally watered plants, the fdl1 transcript level constantly increased during leaf expansion, until it reached a high expression level. In plants exposed to drought stress conditions, the fdl1 transcript level showed a different pattern, with a strong increment in the first day of stress, and then a decrease until the initial level was reached and maintained for the whole duration of drought conditions. We may speculate that the involvement of fdl1 in the plant response to drought conditions, consists in promoting a modification of cuticle composition that will reduce water loss. To further investigate the involvement of fdl1 in drought stress tolerance, its orthologous gene was identified in Eragrostis curvula. This species is particularly interesting for our purposes, because its genome is very similar to the maize genome. Furthermore, unlike maize, in Eragrostis different ecotypes, characterized by different drought stress tolerance, have been described. In a preliminary analysis, we observed that the expression pattern of Ecfdl1 is different among three Eragrostis ecotypes. Differently from what was observed in maize, Ecfdl1 appeared to be expressed in different adult tissues. Moreover, differences in the Ecfdl1 expression profile were detected in different ecotypes. Besides in young maize tissues, fdl1 also appears to have an active role in controlling cuticle deposition in silk tissues. We detected differences between the fdl1-1 mutant and wild type plants in the composition of the wax layer covering the silks. Since maize silks constitute the main route of entry for pathogens to reach the seeds, in our opinion the differences found in silk coverage can influence the plant-pathogen interaction. This hypothesis was confirmed by comparing fusarium ear rot symptoms between wild type and fdl1-1 mutant ears experimentally inoculated with Fusarium verticillioides in a two year experiment. Our results seem to indicate that the fdl1-1 mutant is less susceptible to fusarium infection compared with the wild type. In conclusion to this part of the work, our studies provided details about the involvement of fdl1 in the regulation of cuticle biosynthesis and deposition during two of the most important moments of the plant life cycle: the seedling stage and silk development. Furthermore, in these two delicate moments, we have evidence showing that fdl1 plays an active role in drought stress response and pathogen interaction. In the second chapter, the role of brassinosteroids (BRs) in leaf permeability and architecture was further analysed. BRs are a class of steroid hormones essential for plant growth and development. BRs are involved in many developmental traits of agronomic importance such as seed germination, plant architecture, flowering time and seed yield. In addition to having an important role in development, brassinosteroids exert anti-stress effects on plants and are essential for the ability of plants to adapt to abiotic stresses. This part of the work was focused on the characterization of the maize lilliputian1-1 (lil1-1) mutant, which is impaired in one of the last steps of brassinosteroid biosynthesis. The subtending gene putatively encodes for a brassinosteroid C-6 oxidase (brC-6 oxidase). The mutant appears severely compromised in height, floral development and overall plant architecture. Leaf primordia are more compressed compared with wild type, and mutant leaves appear thicker than wild type leaves, exhibiting altered shape and the presence of supernumerary cell layers in the mesophyll region between the leaf vessels and the adaxial leaf epidermis. In this study, alterations in epicuticular waxes deposition were found in the lil1-1 mutant. Furthermore, it was shown that the leaf epidermis of lil1-1 shows a significantly lower permeability than wild type. These findings are in accordance with previous observations obtained in our laboratory, which showed that the lil1-1 mutant shows a better dehydration tolerance. In our hypothesis, the thicker epidermis observed in lil1-1 compared with wild type, can explain the lower permeability and the better dehydration tolerance. Furthermore, in this chapter we used the lil1-1 mutant to better investigate the BRs biosynthesis pathway. This is a complex pathway and, although it has been the subject of several studies in recent years, some aspects are still to be clarified. For this purpose, we analysed the interaction between the lil1-1 mutant, and another well-known maize BRs mutant, i.e. the nana1-1 (na1-1) mutant. Both nana1 and lil1 genes have key roles in the BR biosynthesis pathway. The product of nana1 is involved in two parallel pathways, therefore lack of its action may lead to an interruption of both. The lil1 gene product, however, is involved in the last steps of the pathway, leading to the formation of castasterone and brassinolide. Our analysis revealed that lil1-1 is epistatic to na1-1. These data suggest the existence in the maize BR pathway of an additional na1-independent branch leading to the production of CS precursors. In conclusion, this part of the work demonstrated the involvement of brassinosteroids in passive leaf permeability and provided new information that will be useful to unravel the complex BR biosynthetic pathway in plants. Overall, the work developed in this thesis project provides indications useful to better understanding the genetic mechanisms that regulate plant resistance to drought and pathogens. A good comprehension of these mechanisms can ultimately be useful to identify new genetic tools of interest, and to develop crops more adapted to the challenges of the future. Because of the appointment with 2050, only 32 annual production cycles remain.

The Mediterranean region is located from the arid climate of North Africa up to the temperate and rainy climate of northern and central Europe. Climate simulations show a gradual increase in heating, drying and precipitation variability in this region. These effects will probably push warmseason turf species towards minor latitudes. The consequences of climate change on turfgrass management have been investigated only recently. Germination and seedling growth have also been little studied for the response to climate change effects, although the establishment phase is central to any high-performing turfgrass. For warmseason grasses in the transition zone, a quick establishment increases winter survival and allows for earlier spring green-up and a more rapid recovery from winter injury. In the Mediterranean region, warm-season grasses are commonly seeded in late spring when the temperatures are suitable for a rapid establishment. Warm-season species used extensively by the turf industry have fertile and sterile cultivars. Seeded cultivars are usually preferred over sterile cultivars because seeding is cheaper and easier to practice than vegetative propagation methods which include plugging, sprigging, and stolonizing. The present study concerns two of the most used warm-season turf species in the Mediterranean area: Bermudagrass (Cynodon spp.) and seashore paspalum (Paspalum vaginatum Swartz) and one potential future new species i.e.buffalograss [Buchloe dactyloides (Nutt.) Engelm.]. The research activity scheduled consisted of five experiments conducted in the field and controlled environments (growth chamber and greenhouse) to investigate the effects of suboptimal temperatures and excess of water due to flooding on seed germination and seedling growth. The main results were the following: Effects of sub-optimal temperatures The warm-season grasses tested germinated at a temperature equal or higher than 11.4 °C (base germination temperature) and early April is the optimal seeding time for establishing by seed warmseason turfgrasses in the Po-Venetian valley. From these results, we have concluded that the predicted warmer springs should lead to earlier seeding of warm-season grasses favouring turfgrass maturation before winter. Effects of water excess All three warm-season turf species under study tolerate flash waterlogging. However, bermudagrass is the one less affected by prolonged waterlogging (6-8 days). In general, warm-season grasses can be successfully used for establishing turfgrasses considering the future climate change predicting the increase of extreme precipitation events.<br>La regione mediterranea è ubicata fra il clima arido del Nord Africa ed il clima temperato e piovoso dell'Europa settentrionale e centrale. Le previsioni sui cambiamenti climatici nei prossimi anni presentano un graduale aumento delle temperature e delle condizioni di aridità, come pure l’aumento di eventi piovosi intensi e localizzati. Per effetto di questi cambiamenti climatici si prevede un crescente impiego di specie macroterme (C4) a latitudini minori comprese quelle utilizzate per la formazione di tappeti erbosi. Le conseguenze sulla gestione del tappeto erboso sono state studiate solo di recente ed inoltre mancano risultati scientifici riguardo gli effetti prodotti dai cambiamenti climatici sulla germinazione e sulle prime fasi di crescita delle plantule. Nella regione mediterranea, le poacee macroterme vengono seminate in tarda primavera, quando le temperature consentono una pronta germinazione ed un rapido insediamento del tappeto erboso. Queste specie presentano sovente cultivar fertili e cultivar sterili che possono essere insediate unicamente per via vegetativa (plugging e stolonizzazione). Le cultivar da seme sono generalmente preferite alle cultivar sterili essendo la semina più economica e più facile da praticare di un insediamento per via vegetativa. Le fasi di insediamento del tappeto erboso seminato sono particolarmente importanti nella gestione dei tappeti erbosi in zone di transizione. Un rapido insediamento, infatti, consente alle specie macroterme di affrontare in condizioni ottimali i rigori invernali e riprendere rapidamente a vegetare in primavera. Il presente studio ha preso in esame due delle specie macroterme da tappeto erboso più utilizzate nell’area mediterranea: gramigna (Cynodon spp.) e paspalum vaginatum (Paspalum vaginatum Swartz) e una specie che potrebbe trovare possibilità di impiego nei prossimi anni e cioè buffalograss [Buchloe dactyloides (Nutt.) Engelm.]. L’attività di ricerca nell’ambito del dottorato prevedeva cinque esperimenti condotti in campo e in ambiente controllato (camera di crescita, serra), finalizzati allo studio degli effetti delle temperature sub-ottimali e dell’eccesso idrico, dovuto ad eventi piovosi intensi, sulla germinazione dei semi e sulla crescita delle plantule delle suddette specie macroterme. I risultati più significativi sono di seguiti riportati. Effetti di temperature non ottimali È stato dimostrato che la germinazione delle specie macroterme testate avviene solamente quando la temperatura è uguale o superiore a 11,4 °C e che l’inizio di aprile può essere considerato il momento ottimale per la semina di tali specie nella pianura padano-veneta. L’incremento termico previsto nei prossimi anni dovrebbe consolidare tali risultati. Una semina ad inizio aprile, diversamente da quanto solitamente avviene (metà-maggio) consente di completare l’insediamento entro maggio, così il tappeto erboso avrà a disposizione l’intera estate per maturare e affrontare nel migliore dei modi l’inverno. Effetti dell'eccesso idrico. Le nostre ricerche hanno evidenziato la spiccata attitudine delle tre specie oggetto di studio a sopportare il ristagno idrico. In particolare, la gramigna è risultata la specie più tollerante all’eccesso idrico nel suolo durante l’insediamento, conservando la germinabilità ed una buona crescita delle plantule anche dopo 6-8 giorni di sommersione. In generale, possiamo affermare che le specie macroterme da tappeto erboso possono essere di grande interesse per la realizzazione di tappeti erbosi nelle condizioni prospettate dai futuri scenari legati al cambiamento climatico.

CAPES<br>Currently there is a need to produce seedlings at low cost and with high quality to be used in the recovery of degraded areas and the use of arbuscular mycorrhizal fungi (AMF) can improve their development in low fertility soils. AMF have several benefits for the plants, because they promote increased survival and establishment of seedlings in the field, as with the symbiosis hyphae improve water use and nutrients. And before this, the present study aimed to evaluate the growth of seedlings Albizia polycephala inoculated with different AMF. First they were produced inoculants through traps vessels with species of native AMF obtained from samplings in the rhizosphere of matrices Albizia polycephala. Later two experiments were conducted, the first being tested five species of AMF from the Collection arbuscular mycorrhizal fungi of Embrapa Agrobiology (COFMEA), mounted in a completely randomized block design with six treatments (control - without inoculation, Scutellospora calospora (T.H. Nicolson & Gerd.) C. Walker & F.E. Sanders, Acaulospora colombiana (Spain & N.C. Schenck) Kaonongbua, J.B. Morton & Bever, Claroideoglomus etunicatum (W.N. Becker & Gerd.) C. Walker & A. Sch??ler, Dentiscutata heterogama (T.H. Nicolson & Gerd.) Sieverd., F.A. Souza & Oehl e Gigaspora margarita W.N. Becker & I.R. Hall) and nine repetitions. In the second experiment inoculants native AMF were tested (native inoculant) and the best species of AMF in the first experiment (Embrapa inoculant). The experimental design was randomized blocks with eight repetitions, in a factorial 3 x 4, that is, three treatments (a witness - no inoculation and two inoculants - native inoculum and mixture of three species from COFMEA) and four doses of P (0, 35, 140 and 350 mg/dm?), applied in the form of superphosphate. The seed Albizia polycephala germinated in trays with sand and vermiculite (2: 1with based on volume) and when the seedlings had a pair of leaves were transplanted with the inoculant in plastic containers of 700 ml with PVC cartridge 380 cm? coupled your background. During the experiments were conducted biweekly measurements of height and diameter and after collection, the root colonization rate assessments, spore density, dry matter of shoot, root dry matter, reason root /shoot and leaf phosphorus content . The results obtained through the evaluations showed that the species of Acaulospora colombiana was the most effective in promoting the growth of Albizia polycephala. Furthermore, the inoculant of COFMEA provided better growth in different phosphorus levels than native inoculant. Thus, it can be stated that the tested species has association with AMF efficiently and has high dependence mycorrhizal.<br>Atualmente existe a necessidade de se produzir mudas a baixo custo e com ?tima qualidade para serem utilizadas na recupera??o de ?reas degradadas e a utiliza??o dos fungos micorr?zicos arbusculares (FMAs) pode melhorar o seu desenvolvimento em solos de baixa fertilidade. Os FMAs apresentam v?rios benef?cios para as plantas, pois promovem uma maior sobreviv?ncia e estabelecimento das mudas no campo, j? que com a simbiose as hifas melhoram o aproveitamento de ?gua e nutrientes. E diante disso o presente trabalho teve como objetivo geral avaliar o crescimento de mudas de Albizia polycephala inoculadas com diferentes FMAs. Primeiramente foram produzidos inoculantes atrav?s de vasos armadilhas com esp?cies de FMAs nativos, obtidos a partir de coletas de solo na rizosfera de matrizes de Albizia polycephala. Posteriormente foram realizados dois experimentos, sendo no primeiro testadas cinco esp?cies de FMAs provenientes da Cole??o de fungos micorr?zicos arbusculares da Embrapa Agrobiologia (COFMEA), em blocos inteiramente casualizados, com seis tratamentos (Testemunha ? sem inocula??o, Scutellospora calospora (T.H. Nicolson & Gerd.) C. Walker & F.E. Sanders, Acaulospora colombiana (Spain & N.C. Schenck) Kaonongbua, J.B. Morton & Bever, Claroideoglomus etunicatum (W.N. Becker & Gerd.) C. Walker & A. Sch??ler, Dentiscutata heterogama (T.H. Nicolson & Gerd.) Sieverd., F.A. Souza & Oehl e Gigaspora margarita W.N. Becker & I.R. Hall) e nove repeti??es. No segundo experimento foram testados os inoculantes de FMAs nativos (inoculante nativo) e as melhores esp?cies de FMAs do primeiro experimento (inoculante Embrapa). O delineamento experimental utilizado foi em blocos casualizados com oito repeti??es, em fatorial 3 x 4, ou seja, tr?s tratamentos (uma testemunha ? sem inocula??o e dois inoculantes ? in?culo nativo e mistura de tr?s esp?cies provenientes da COFMEA) e quatro doses de P (0, 35, 140 e 350 mg/dm?), aplicado na forma de superfosfato simples. As sementes de Albizia polycephala germinaram em bandejas contendo areia e vermiculita (2:1com base em volume) e quando as pl?ntulas tinham um par de folhas foram transplantadas junto com o inoculante em recipientes pl?sticos de 700 ml com tubete de PVC de 380 cm? acoplado em seu fundo. Durante os experimentos foram realizadas medi??es quinzenais de altura e di?metro e ap?s a coleta, as avalia??es de taxa de coloniza??o da raiz, densidade de esporos, mat?ria seca da parte a?rea, mat?ria seca da raiz, raz?o raiz/parte a?rea e teor de f?sforo foliar. Os resultados obtidos atrav?s das avalia??es mostraram que a esp?cie de Acaulospora colombiana foi a mais eficiente em promover o crescimento de Albizia polycephala. Al?m disso, o inoculante da COFMEA proporcionou melhores crescimentos em diferentes doses de f?sforo do que o inoculante nativo. Desta forma, pode-se afirmar que a esp?cie testada apresenta associa??o com FMAs de forma eficiente e tem alta depend?ncia micorr?zica.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-06T12:56:39Z No. of bitstreams: 1 2015 - Pedro Lima Filho.pdf: 2041277 bytes, checksum: b01482f603e849269eed9abdd8b8432c (MD5)<br>Made available in DSpace on 2017-01-06T12:56:39Z (GMT). No. of bitstreams: 1 2015 - Pedro Lima Filho.pdf: 2041277 bytes, checksum: b01482f603e849269eed9abdd8b8432c (MD5) Previous issue date: 2015-05-22<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES<br>One of the main problems found in forestry stands intended for restoration is seedling quality. The goal of this research was to evaluate different tube volumes in seedling production, utilizing biosolid as the substrate, within the following species; Ceiba speciosa, Pseudobombax grandiflorum, Dalbergia nigra and Lafoensia glyptocarpa,. The experiment consisted of the seedling production stage and a development evaluation stage in the field. The treatments utilized were 55, 110, 180 and 280 cm? tubes. The seedling production phase was done under entirely randomized design composed of four replications of the 12 seedlings. The field phase was also done under entirely randomized design due to the seedling formation period, which was in different periods for each species. The 280 cm? tube provided the best seedling quality, regardless of the species, when the biosolid was utilized as substrate. Despite this, for the species Pseudobombax grandiflorum, Dalbergia nigra and Lafoensia glyptocarpa, it is possible to utilize the 180 cm? tubet for seedling formation while maintaining similar quality<br>Um dos principais problemas encontrados na forma??o de povoamentos visando ? restaura??o florestal ? a qualidade das mudas. O objetivo deste trabalho foi avaliar diferentes volumes de tubetes para a produ??o de mudas de Ceiba speciosa, Pseudobombax grandiflorum, Dalbergia nigra e Lafoensia glyptocarpa, utilizando o bioss?lido como substrato. O experimento constou da fase de produ??o das mudas e da avalia??o do desempenho dessas no campo. Os tratamentos utilizados foram os tubetes de 55, 110, 180 e 280 cm?. A fase de produ??o das mudas foi instalada em delineamento inteiramente casulalizado composto por quatro repeti??es de 12 mudas. A fase de campo tamb?m foi instalada em delineamento inteiramente causualizado. Devido ao tempo de forma??o das mudas, em ?pocas diferentes para cada esp?cie. O tubete de 280 cm? foi o que proporcionou a melhor de qualidade de mudas, independente da esp?cie, quando se utilizou o bioss?lido como substrato. Todavia, para as esp?cies Pseudobombax grandiflorum, Dalbergia nigra e Lafoensia glyptocarpa pode-se utilizar o tubete de 180 cm? para a forma??o das mudas, mantendo qualidade similar

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-08-30T16:36:02Z No. of bitstreams: 1 2009 - Aldir Carlos Silva.pdf: 1230710 bytes, checksum: 56dbab398ff37045b73bd259ab1a15ac (MD5)<br>Made available in DSpace on 2018-08-30T16:36:02Z (GMT). No. of bitstreams: 1 2009 - Aldir Carlos Silva.pdf: 1230710 bytes, checksum: 56dbab398ff37045b73bd259ab1a15ac (MD5) Previous issue date: 2009-03-06<br>Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq<br>Aluminum tolerance studies in seedlings of Passion fruit (cvs. IAC-273/277, IACPaulista, IAC-275, FB-100) and Carica papaya (cvs.Taiung, Golden, Gran Golden, Baixinho de Santa Amalia) were performed in a growth chamber at the Laboratories of Chemistry of the Rhizosphere and Seeds of the Department of Fitotecnia, of University Federal Rural of Rio Janeiro, Institute of Agronomy. Experiments with different concentrations of Al were conducted in nutrient solution simple (with Ca) and complete, with the aims to analyze the tap root length, ratio of root lengths, relative root elongation, diameter of root and stem and effect of stains. Also were conducted experiments with seeds soaked in different concentration of Al to verify the percentage of germination, seedlings normal and abnormal. The use of simple nutrient solution was not satisfactory to shown the performance of seedlings of papaya. In passion fruit both nutrient solutions can be used in short term experiment. Over the concentration of 160?M of Al occurred effect of toxicity in root of seedlings of passion fruit and papaya, but at concentrations lower that 80?M there were stimulus of growth. The tap root length was the more efficient parameter to compare root toxicity. The soaking of seeds in the solution of aluminum did not affect the germination, root tap emission and the growth of seedlings until 1280?M. With the increased of time of contact with the Al solution, the young roots have been injured especially in papaya seedlings. The use of stains pyrocatechol violet and hematoxylin were both efficient to determinate the aluminum tolerance in papaya and passion fruit, but just pyrocatechol violet could compare the doses used, produced a color gradient with increasing concentration of aluminum. With the use of hematoxylin was only possible to separate the high concentrations of low concentrations of aluminum. The best passion fruit cultivar was IAC 273/277and papaya was Tainung<br>Os estudos da toler?ncia ao alum?nio em pl?ntulas de maracuj? (cvs. IAC-273/277, IACPaulista, IAC-275, FB-100) e mam?o (cvs.Tainug, Golden, Gran Golden, Baixinho de Santa Am?lia) foram realizados, em c?mara de crescimento nos Laborat?rios de Qu?mica da Rizosfera e Laborat?rio de Analise de Sementes, Departamento de Fitotecnia, Instituto de Agronomia da Universidade Federal Rural Rio de Janeiro. Foram realizados experimentos com diferentes concentra??es de alum?nio em solu??o nutritiva simples (com c?lcio) e completa, para analise do crescimento radicular utilizando os par?metros comprimento radicular, taxa de crescimento radicular, elonga??o radicular relativa, di?metro do colo, di?metro de ?pice da raiz principal bem como testes com corantes. Foi tamb?m realizado estudos do efeito da embebi??o das sementes com solu??es de alum?nio para verificar o efeito na porcentagem de germina??o, pl?ntulas normais e anormais, e n?o germinadas. O uso da solu??o nutritiva simples para realizar testes de curta dura??o de contacto ao alum?nio, n?o foi satisfat?rio para mam?o, sendo mais adequado o uso de solu??o nutritiva completa. Em maracuj?, ambas as solu??es podem ser utilizadas. As pl?ntulas de maracuj? crescidas em solu??o simples com o aumento do tempo de contacto com alum?nio na solu??o, as ra?zes ficaram endurecidas. Em concentra??es acima de 160?M de alum?nio, ocorreu efeito fitotoxico, contudo em concentra??es menores que 80?M ocorreu at? aumento do crescimento radicular para mam?o e maracuj?. O comprimento radicular foi o mais eficiente par?metro indicador da toler?ncia ao alum?nio. A embebi??o das sementes em alum?nio n?o afetou a germina??o a emiss?o da raiz principal e o crescimento da pl?ntula at? a concentra??o da solu??o de embebi??o de 1280?M, mas a medida que aumentou o tempo de contato e a concentra??o de alum?nio, as ra?zes rec?m emitidas sofreram danos, principalmente as de pl?ntulas de mam?o. O uso dos corantes qu?micos violeta de pirocatecol e hematoxilina foram eficiente na determina??o da toler?ncia ao alum?nio em maracuj? e mam?o, mais somente o violeta de pirocatecol permitiu comparar as doses entre si, gerando um gradiente de colora??o com o aumento da concentra??o de alum?nio, com o uso da hematoxilina s? foi poss?vel separar as concentra??es altas das concentra??es baixas de alum?nio. As melhores cultivares nas condi??es testadas foi a IAC 273/277 de maracuj? e a cv Tainung de mam?o

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-11T13:54:16Z No. of bitstreams: 1 2011 - Jorge Makhlouta Alonso.pdf: 2171400 bytes, checksum: e641011cdcb7b32ae286a3b24cb5852c (MD5)<br>Made available in DSpace on 2016-10-11T13:54:16Z (GMT). No. of bitstreams: 1 2011 - Jorge Makhlouta Alonso.pdf: 2171400 bytes, checksum: e641011cdcb7b32ae286a3b24cb5852c (MD5) Previous issue date: 2011-01-31<br>Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq<br>The demand for forest restoration projects grows increasingly in the State of Rio de Janeiro. One of the difficulties that these projects are having is the lack of knowledge about the regional offer of seedlings of native species. This study aims to evaluate the nurseries and seedling production of species from the Atlantic Forest in the state of Rio de Janeiro, as well as analyze the Brazilian legislation about production of forest seeds and seedlings. To conduct the study on legislation, researches were made in internet sites of federal agencies. The legal instruments found were discussed, considering the political and historical context of each era. For evaluation of nurseries and seedling production, was used data from the "Diagnostic of Seeds Collection and Seedlings Production in Rio de Janeiro", coordinated by the Secretariat of State for the Environment ? SEA-RJ, in partnership with other institutions. The study was conducted in the state of Rio de Janeiro from February to April 2010. In the diagnostic were included the nurseries producing seedlings of Atlantic Forest species, regardless of the amount, purpose and destination of then. The field work consisted of visits to the 70 nurseries surveyed, in which was applied an structured questionnaire addressing various topics related to the nursery and the seedling production, requested a list of the species produced, performed the photographic record of the nursery and marked its geographic coordinates. It was noted that the new legislation concerning forest seeds and seedlings established requirements for producers in order to guarantee for the consumer the identity and quality of what is produced. However, some issues need to be reviewed and best formulated aiming at reducing the "distance" between legislation and the reality of the producer of forest seeds and seedlings. The 70 nurseries are concentrated in some cities and regions, not covering the state as a whole. Regarding the administrative structure, the nurseries of the state, are mostly small sized, administered by public agencies and many of them lacks infrastructure for seedling production. Only 5 of 70 nurseries are registered to the RENASEM / MAPA as required by the current legislation. The seedlings are produced with low diversity of species, predominance of plastic bags as recipients and little technical and managerial control over the production. The data shows that the activity still have a lot to develop in the state, being necessary public policies aiming reinforce the existing nurseries, stimulate Atlantic Forest restoration plantations and, consequently, the demand for native forest seedlings<br>No Estado do Rio de Janeiro cresce cada vez mais a demanda por projetos de restaura??o florestal. Uma das dificuldades desses projetos ? o desconhecimento da oferta regional de mudas de esp?cies florestais nativas. O presente trabalho tem como objetivo avaliar os viveiros e a produ??o de mudas florestais da Mata Atl?ntica no Estado do Rio de Janeiro, bem como realizar uma an?lise da legisla??o federal referente ? produ??o de sementes e mudas florestais. Para realizar o estudo referente ? legisla??o foram feitas consultas na internet a sites de ?rg?os p?blicos federais. Os instrumentos legais encontrados foram discutidos, considerando o contexto pol?tico e hist?rico de cada ?poca. Para avalia??o dos viveiros e da produ??o de mudas, foram utilizados os dados do ?Diagn?stico de Coleta de Sementes e Produ??o de Mudas no Rio de Janeiro?, coordenado pela Secretaria de Estado do Ambiente ? SEA, em parceria com outras institui??es. O estudo foi realizado no Estado do Rio de Janeiro de fevereiro a abril de 2010. Foram inclu?dos no diagn?stico, os viveiros florestais que produziam mudas de esp?cies da Mata Atl?ntica, independente da quantidade, finalidade e destina??o das mesmas. A etapa de campo do diagn?stico consistiu em visitas aos 70 viveiros levantados, nas quais foi aplicado question?rio estruturado abordando v?rios temas relacionados ao viveiro e a produ??o de mudas, requerida uma lista das esp?cies produzidas, realizado o registro fotogr?fico do viveiro e marcadas suas coordenadas geogr?ficas. Observou-se que a nova legisla??o referente ?s sementes e mudas florestais criou exig?ncias para os produtores, visando garantir ao consumidor a identidade e a qualidade do que ? produzido. No entanto, algumas quest?es precisam ser revisadas e melhor formuladas visando diminuir a ?dist?ncia? existente entre a legisla??o e a realidade do produtor de sementes e mudas florestais. Os 70 viveiros est?o concentrados em alguns munic?pios e regi?es, n?o abrangendo o estado como um todo. Com rela??o ? estrutura administrativa, os viveiros do estado, s?o em maioria administrados por ?rg?os p?blicos, de pequeno porte e carecem de infraestrutura para produ??o de mudas. Apenas cinco entre os 70 viveiros est?o inscritos no RENASEM conforme exigido pela atual legisla??o. As mudas s?o produzidas com baixa diversidade de esp?cies, predomin?ncia de sacos pl?sticos como recipiente e pouco controle t?cnico e gerencial sobre a produ??o. Os dados demonstram que a atividade ainda tem muito a evoluir no estado, sendo necess?rias pol?ticas p?blicas visando fortalecer os viveiros j? existentes, estimular plantios de restaura??o da Mata Atl?ntica e consequentemente, a demanda por mudas florestais nativas.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-20T11:07:04Z No. of bitstreams: 1 2013 - Jorge Makhlouta Alonso.pdf: 2171400 bytes, checksum: eec9c3f847abd21fecbe9f0f7dea6dbb (MD5)<br>Made available in DSpace on 2016-10-20T11:07:04Z (GMT). No. of bitstreams: 1 2013 - Jorge Makhlouta Alonso.pdf: 2171400 bytes, checksum: eec9c3f847abd21fecbe9f0f7dea6dbb (MD5) Previous issue date: 2013-01-31<br>Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq<br>The demand for forest restoration projects grows increasingly in the State of Rio de Janeiro. One of the difficulties that these projects are having is the lack of knowledge about the regional offer of seedlings of native species. This study aims to evaluate the nurseries and seedling production of species from the Atlantic Forest in the state of Rio de Janeiro, as well as analyze the Brazilian legislation about production of forest seeds and seedlings. To conduct the study on legislation, researches were made in internet sites of federal agencies. The legal instruments found were discussed, considering the political and historical context of each era. For evaluation of nurseries and seedling production, was used data from the "Diagnostic of Seeds Collection and Seedlings Production in Rio de Janeiro", coordinated by the Secretariat of State for the Environment ? SEA-RJ, in partnership with other institutions. The study was conducted in the state of Rio de Janeiro from February to April 2010. In the diagnostic were included the nurseries producing seedlings of Atlantic Forest species, regardless of the amount, purpose and destination of then. The field work consisted of visits to the 70 nurseries surveyed, in which was applied an structured questionnaire addressing various topics related to the nursery and the seedling production, requested a list of the species produced, performed the photographic record of the nursery and marked its geographic coordinates. It was noted that the new legislation concerning forest seeds and seedlings established requirements for producers in order to guarantee for the consumer the identity and quality of what is produced. However, some issues need to be reviewed and best formulated aiming at reducing the "distance" between legislation and the reality of the producer of forest seeds and seedlings. The 70 nurseries are concentrated in some cities and regions, not covering the state as a whole. Regarding the administrative structure, the nurseries of the state, are mostly small sized, administered by public agencies and many of them lacks infrastructure for seedling production. Only 5 of 70 nurseries are registered to the RENASEM / MAPA as required by the current legislation. The seedlings are produced with low diversity of species, predominance of plastic bags as recipients and little technical and managerial control over the production. The data shows that the activity still have a lot to develop in the state, being necessary public policies aiming reinforce the existing nurseries, stimulate Atlantic Forest restoration plantations and, consequently, the demand for native forest seedlings.<br>No Estado do Rio de Janeiro cresce cada vez mais a demanda por projetos de restaura??o florestal. Uma das dificuldades desses projetos ? o desconhecimento da oferta regional de mudas de esp?cies florestais nativas. O presente trabalho tem como objetivo avaliar os viveiros e a produ??o de mudas florestais da Mata Atl?ntica no Estado do Rio de Janeiro, bem como realizar uma an?lise da legisla??o federal referente ? produ??o de sementes e mudas florestais. Para realizar o estudo referente ? legisla??o foram feitas consultas na internet a sites de ?rg?os p?blicos federais. Os instrumentos legais encontrados foram discutidos, considerando o contexto pol?tico e hist?rico de cada ?poca. Para avalia??o dos viveiros e da produ??o de mudas, foram utilizados os dados do ?Diagn?stico de Coleta de Sementes e Produ??o de Mudas no Rio de Janeiro?, coordenado pela Secretaria de Estado do Ambiente ? SEA, em parceria com outras institui??es. O estudo foi realizado no Estado do Rio de Janeiro de fevereiro a abril de 2010. Foram inclu?dos no diagn?stico, os viveiros florestais que produziam mudas de esp?cies da Mata Atl?ntica, independente da quantidade, finalidade e destina??o das mesmas. A etapa de campo do diagn?stico consistiu em visitas aos 70 viveiros levantados, nas quais foi aplicado question?rio estruturado abordando v?rios temas relacionados ao viveiro e a produ??o de mudas, requerida uma lista das esp?cies produzidas, realizado o registro fotogr?fico do viveiro e marcadas suas coordenadas geogr?ficas. Observou-se que a nova legisla??o referente ?s sementes e mudas florestais criou exig?ncias para os produtores, visando garantir ao consumidor a identidade e a qualidade do que ? produzido. No entanto, algumas quest?es precisam ser revisadas e melhor formuladas visando diminuir a ?dist?ncia? existente entre a legisla??o e a realidade do produtor de sementes e mudas florestais. Os 70 viveiros est?o concentrados em alguns munic?pios e regi?es, n?o abrangendo o estado como um todo. Com rela??o ? estrutura administrativa, os viveiros do estado, s?o em maioria administrados por ?rg?os p?blicos, de pequeno porte e carecem de infraestrutura para produ??o de mudas. Apenas cinco entre os 70 viveiros est?o inscritos no RENASEM conforme exigido pela atual legisla??o. As mudas s?o produzidas com baixa diversidade de esp?cies, predomin?ncia de sacos pl?sticos como recipiente e pouco controle t?cnico e gerencial sobre a produ??o. Os dados demonstram que a atividade ainda tem muito a evoluir no estado, sendo necess?rias pol?ticas p?blicas visando fortalecer os viveiros j? existentes, estimular plantios de restaura??o da Mata Atl?ntica e consequentemente, a demanda por mudas florestais nativas

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-09T11:54:46Z No. of bitstreams: 1 2016 - David da Cunha Valen?a.pdf: 2653024 bytes, checksum: d2b4461225be75ec25872fbc06de8bdb (MD5)<br>Made available in DSpace on 2017-01-09T11:54:46Z (GMT). No. of bitstreams: 1 2016 - David da Cunha Valen?a.pdf: 2653024 bytes, checksum: d2b4461225be75ec25872fbc06de8bdb (MD5) Previous issue date: 2016-02-24<br>Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ - FAPERJ<br>The concern with the intensive use of natural resources has become increasingly justifying the development of new technologies aiming their rational use such as automated irrigation systems. The automation of irrigation could to allow water saving increasing efficiency of its use in agricultural production. The first chapter of this study was to evaluate five different volumes (130, 100, 80, 60 and 33% of volume of Simplified Irrigation Controller - SIC) in the production of lettuce in pots in a production system called "Organic Potponics". It was used the SIC, whose operation is based on tension in the soil solution. The different volumes were achieved by drippers association of different flow rates in the same pipe. It was evaluated fresh and dry weight, number of leaves and diameter of lettuce plants (production variables); stomatal conductance, chlorophyll content, relative water content in leaves and chlorophyll fluorescence (physiological variables); and the water use efficiency (WUE). The corresponding volume 126% specified by the SIC installed to a tension soil of 6 kPa was that provided the best results production of dry weight, whereas the maximal WUE was obtained for the corresponding slide 80%. It indicates the volume of 83%, because it provided the best economy of water and a satisfactory production to sale. In the second chapter aimed to evaluate the use of the SIC under four different tensions to the substrate for the production of lettuce seedlings in trays under greenhouse conditions. It was evaluated fresh and dry weight of shoots, number of leaves, shoot height, leaf length and leaf area (production variables); chlorophyll content (physiological variable); and WUE. Higher water stress in the substrate decreased irrigation events, harming the growth of linearly seedlings and causing large percentage of deaths. The tension of 4 kPa was the one that provided the highest values in all production variables. The tension of 6.5 kPa despite having a percentage of death, can be used to produce more resistant seedlings<br>A preocupa??o com o uso intensivo dos recursos naturais tem se tornado cada vez maior, justificando o desenvolvimento de novas tecnologias que buscam sua aplica??o racional, como dispositivos autom?ticos de irriga??o. A automa??o da irriga??o pode permitir a economia da ?gua aumentando a efici?ncia de seu uso na produ??o agr?cola. O primeiro cap?tulo desse estudo teve como objetivo avaliar cinco diferentes volumes de irriga??o (130, 100, 80, 60 e 33% do volume do Acionador Simplificado de Irriga??o - ASI) na produ??o de alface em vasos em um sistema de produ??o denominado ?Vasoponia Org?nica?. Foi utilizado o ASI, cujo funcionamento baseia-se na tens?o da solu??o do solo. Os diferentes volumes foram conseguidos pela associa??o de gotejadores de vaz?es distintas em uma mesma tubula??o. Foram avaliados pesos fresco e seco, n?mero de folhas e di?metro das plantas de alface (vari?veis de produ??o); condut?ncia estom?tica, Teor de clorofila, conte?do relativo de ?gua nas folhas e fluoresc?ncia da clorofila (vari?veis fisiol?gicas); al?m da efici?ncia de uso da ?gua (EUA). O volume correspondente a 126% do indicado pelo ASI, instalado para tens?o de 6 kPa no solo, foi a que proporcionou os melhores resultados de produ??o de massa seca, enquanto que a m?xima EUA foi obtido para a l?mina correspondente a 83%. Indica-se o volume de 83%, pois proporcionou a melhor economia de ?gua e uma produ??o satisfat?ria ? comercializa??o. No segundo cap?tulo, objetivou-se avaliar a utiliza??o do ASI sob quatro diferentes tens?es no substrato para a produ??o de mudas de alface em bandejas de isopor em ambiente protegido. Foram avaliados peso fresco e da parte a?rea, n?mero de folhas, altura da parte a?rea, comprimento de folhas e ?rea foliar (vari?veis de produ??o); teor de clorofila (vari?vel fisiol?gica); al?m da EUA. Maiores tens?es de ?gua no substrato diminu?ram o n?mero de eventos de irriga??o, prejudicando o crescimento das mudas de forma linear e ocasionando grande percentual de mortes. A tens?o de 4 kPa foi a que proporcionou os maiores valores em todas as vari?veis de produ??o. A tens?o de 6,5 kPa apesar de apresentar um percentual de morte, pode ser utilizada para a produ??o de mudas mais resistentes.

Herbicide resistance is evolving fast in Italy, especially in cropping systems characterised by low diversity in space and time. In these systems there is often no rotation of herbicides mode of action (i.e. durum wheat and rice monoculture). Resistance is also evolving faster in cross-pollinating and genetically variable species (i.e. Lolium spp.). In Italy about 100,000 ha have been estimated to suffer resistant problems, mainly in durum wheat (Lolium spp., Avena sterilis and Papaver rhoeas) and paddy rice (mostly Schoenoplectus mucronatus and Cyperus difformis). ACCase is an essential enzyme in fatty acid biosynthesis in eukaryotes and prokaryotes. In plants, two forms of ACCase have been identified - the first is located in the chloroplast, the primary site of plant fatty acid biosynthesis, and the second in the cytosol. The homomeric ACCase in the cytosol of nearly all plant species and the heteromeric ACCase in the chloroplasts of dicots are insensitive to APP, CHD and DEN herbicides. In contrast, the plastidic homomeric ACCase in nearly all grass species is herbicide-sensitive, and this is the basis for selective control of grass-weeds by ACCase herbicides. The aims of the research were: (1) to monitor throughout the country the situation of resistance to Acetyl-CoA Carboxylase (ACCase) in Lolium and Phalaris species following complaints to the agrochemical industries; (2) to develop a reliable Petri dish quick test to detect ACCase-inhibitors resistance in Lolium and Phalaris species; (3) to characterise clethodim and pinoxaden resistance in Lolium spp. using different experimental approaches; (4) agronomic and molecular characterisation of a few populations of P. paradoxa resistant to ACCase inhibitors. Through classic pot screenings, populations with different patterns and levels of resistance have been selected to be studied with different approaches: outdoor dose-response, at molecular level using molecular markers and sequencing and at physiological level through enzyme bioassay. As pot experiments are costly and time consuming, a rapid test in Petri dishes based on survival data has been developed for detecting resistance to ACCase-inhibitors. Screening results revealed that among 41 tested Lolium populations, 23 were resistant to clodinafop, 19 to sethoxydim and 15 to pinoxaden. Among the 17 P. paradoxa populations, 3 were resistant to clodinafop, and one to sethoxydim and pinoxaden. Resistance to pinoxaden is associated to a wide pattern of cross-resistance among ACCase-inhibitors. The Petri dish seed quick test has been developed in order to find a discriminating herbicide concentration between susceptible and resistant populations; a herbicide concentration ("comparing dose") that gives results comparable to the recommended field dose used in greenhouse pot experiments; and a concentration discriminating between strong and weak resistance. The "comparing doses" has been validated using other populations not included in the set up experiments. The "comparing dose" for Lolium spp. have been: clodinafop 1 ?M, pinoxaden 0.2 ?M, clethodim 0.2 ?M and sethoxydim 0.1 ?M; for P. paradoxa, clodinafop 0.1 ?M, pinoxaden 0.05 ?M and clethodim 0.1 ?M. The Petri dish seed quick test revealed to be reliable with the two species in screening large numbers of samples compared with the costly and time consuming pot experiment. The quick test improves ACCase-resistance detection and can be adopted as a routine facility. Molecular investigation identified five ACCase mutations (Ile1781Leu, Trp2027Cys, Ile2041Asn, Asp2078Gly and Cys2088Arg) and revealed 12 genotypes in 14 clethodim resistant Lolium populations. Pinoxaden resistance has been reported associated to Lolium population mutants for five ACCase mutations (Ile1781Leu, Ile2041Val/Asn, Asp2078Gly, Cys2088Arg and Gly2096Ala) with specific homozygous and heterozygous status among mutations. In P. paradoxa two mutations have been associated to pinoxaden resistance: Ile1781Val and Asp2078Gly, always recognised at the homozygous status. The research has established that resistance to ACCase herbicides depends on the specific resistant allele(s), on the homo/heterozygous status of plants for the specific resistant allele(s), and on the combinations of different resistant alleles, as well as herbicide rates. To understand and devise resistance management strategies, knowledge of all these factors coupled with field records of herbicide and agronomic techniques used is essential. The overall situation of grass resistance in Italian durum wheat crops indicates that there is no single chemical that can solve all resistance problems. Therefore all stakeholders should be aware that IWM (or better ICM) is needed to properly manage resistance in the field. It must also be clear that IWM or ICM requires a higher technological level coupled with a deeper knowledge of all components of the cropping system.

Au cours du travail présenté dans ce mémoire, nous sommes parvenus à obtenir, de façon systématique, la micropropagation in vitro et l'acclimatation ex vitro non seulement des poiriers juvéniles issus de pépins de "passe crassane", mais aussi du cognassier de Provence et de deux cultivars de poirier, "williams" et "passe crassane". Les conditions de culture concernant les différentes phases de la micropropagation et l'acclimatation ont été étudiées. Plusieurs problèmes d'ordre physiologique (dormance des bourgeons in vitro, anomalie des pousses formées, nécrose des apex) ont pu être surmontés ou limités.

碩士<br>國立中興大學<br>園藝學系<br>82<br>Onion seedlings raised in plug had larger size and better recovery after transplanting than control of seedlings grown in in field for 45 days. Bulb yield and uniformity of Granex 429 are improved by plug seedlings. Days to bulb onset are five days earlier in plug seedlings of Granex 429 than controls. Leaf weight ratio data showed plug seedling could shorten the days to harvest of Granex 429, but not for Superex. There is no signific- ant difference in earlyness and yield of Superex between seedling either raised in plugs or field, but plug seedling had higher percentage of bigger bulbs. Older plug seedlings had bigger size during nursery stage and after transplanting, but young seedlings were better in recovery . At harvest, 45 days old plug seedlings showed earlier maturity and less total yield than 55 days old seedlings in culitivar Granex 429 and Grano 502, but not significant in Superex. Science root development are restricted by plug size, seedlings raised in small plugs are smaller than raised in bigger plugs. Growth restricting is shown at the 45 to 55 days of 128 and 288 cells plug and three weeks in plug of 406 cells. No significant difference is observed between seedlings in 128, 200 and 406 plugs on maturity, yield, uniformity and quality of bulbs. Cannonical varables of onion seedling are consist of 10 characters ie. leaf fresh weight, root dry weight, leaf number, leaf length, root number, root number, root length, length of pseudostem, diameter of pseudostem, bulb ratio and seedling growth rate. The cannonical correlation coefficient between general plant size index, root size index and their paired cannonical variables described that the early stage of transplant -ing and bulbing are 0.9634 and 0.7084, the coefficient of determinate are 0.9282 and 0.5018 respectively. Theses two index could quantify and compare the quality of onion seedlings.

碩士<br>國立中興大學<br>園藝學系<br>84<br>Three tomato cultivars (Lycopersicon esculentum Mill.) were planted in Spring, Summer and Fall 1995 to evaluate seedling growth and early fruit yield in response to age of plug seedling.Increasing seedling age would increase plant height, leaf area, shoot and root dry weight, but smaller root:shoot ratio which may be due to the root-restriction stress in small cell size (25ml/cell). The younger seedlings were better in recovery after transplanting, except 5w transplants in summer which showed slower growth rate. One week after transplanting, mean relative growth rate of 5w transplants in summer was only 84.7 mg/gweek which is significantly less than 7w and 9w transplants of 830.5 and 528.6mg/gweek, respectively. Effects of age on growth in spring were not significant at 3 weeks after transplanting. In summer and fall crops the influence of age continued for 4 weeks after transplanting. Cultivars of ''Known You 301'' and ''Asia Veg. No4.'' had similar growth pattern and showed bigger seedling than ''Red Crown'' before transplanting except the root:shoot ratio as well as the restoration growth of transplants after transplanting.The days to flowering after transplanting mainly affected by cultivars and crop seasons. Transplants of ''Red Crown'' began to flower about 2 days earlier than ''Known You 301'' and ''Asia Veg. No.4'', while transplants in spring crop flowered 14 and 21 days earlier than summer and fall crops, respectively. There were no significant differences among transplant age. The younger transplants had fewer internodes preceding to the first inflorescence. Plants grown in spring showed 5-10 internodes less than plants in summer and fall crops.Croping date and cultivars were the major factors influenced the early and marketabl yields. Summer crop had the least yield. Cultivar ''Red Crown'' produced the greatst early and marketable yield. ''Known You 301'' had higher percentage of large fruits in early yield, although fruits harvested were the least. Both early and marketable yields were unaffected by seedling age at transplanting.

碩士<br>國立嘉義大學<br>園藝學系研究所<br>98<br>This study aimed to identify effects of nutrition managements at the seedling stage, seedling age and planting period on the growth and flowering of Eustoma grandiflorum. Eight cultivars of E. grandiflorum, including of ‘New Lination White’, ‘Lination Pink’, ‘Exrosa Pink Flash’, ‘Exrosa Green’, ‘Cute Snow’, ‘Noble Jade’, ‘Tsukushi no Nami’ and ‘Tsukushi no Hagoromo’ were subirrigated with 0.5 or 1.0 gL-1 of Peters 20-20-20 and Peters 30-10-10 every 5 to 7 days, respectively. The results showed the size of the second pair of true leaves and fresh weight of these cultivars showed better in subirrigation with Peters 30-10-10 1.0 gL-1. For these same cultivars, the combination of 1.0 gL-1 Peters 30-10-10 and 1.0 gL-1 Hyponex 20-20-20 by foliar spraying every 3 days can promote the second pair of true leaves larger, the root longer and the upper and lower part fresh weight heavier than 0 and 0.5 gL-1 Hyponex 20-20-20. The eight, nine and ten-week-age seedlings of six E. grandiflorum cultivars ‘New Lination White’, ‘Lination Pink’, ‘Exrosa Pink Flash’, ‘Exrosa Green’, ‘Cute Snow’, and ‘Cute Green ver. 2’ were planted in the field in different times of Jan., May., Sep. and Nov.; and these cultivars didn’t rosette. For eight and nine-week-age seedlings planted in May and Sep., the flowering time was shorter, the plant height was shorter, the stem was slimmer, the number of internodes was fewer, and the node number for the first flower appearance was lower. For the ten-week-age seedlings planted in Jan. and eight and nine-week-age seedlings planted in Nov. have longer flowering time, higher height, thicker stem, more inter-node number, and higher node number for the initial flowering. The number of petals of flowers was more for plants planted in Jan. and Nov. Otherwise the number of flower buds was more when planted in May and Nov. than other seasons. According to our results, we suggest that the growth and quality of seedlings can be promoted by the nutrition management of E. grandiflorum subirrigated with 1.0 gL-1 Peters 30-10-10 and foliar fertilized with 1.0 gL-1 Hyponex 20-20-20 simultaneously at the conditions of 24/18℃ (day/night) for 8weeks. In this study, the eight and nine-week-age seedlings of six cultivars can be planted in Nov. and ten-week-age seedlings in Jan. to achieve higher cut-flower quality.

碩士<br>國立臺灣大學<br>園藝學研究所<br>90<br>To assess the temperature effect on vegetative and reproductive growth in celery(Apium graveolens L.), leaf formation, plant height and other growth characteristics are monitored in two local varieties cvs. ‘Hainan-Chin’ and ‘Huang-Hsin’. The study also found out the effects of vernalization and seedling age on bolting and flowering are studied with 4 varieties, cvs. ‘Hainan-Chin’(green leaf and petiole)、‘Huang-Hsin’(yellow leaf and petiole)、‘Shii-Shu Late’(green leaf yellow petiole) and ‘Ching-Torng’(green flower stalked). In the phytotron of National Taiwan University, day/night temperatures of 35/30, 30/25, 25/20, 20/15, and 15/13℃ formulated the temperature treatments. For both celery cultivars the vegetative growth was retarded under 35/30℃ and 30/25℃ regimes in terms of shorter petiole, smaller stem girth and smaller biomass. The celery ‘Hainan-Chin’ grows fetter in 20/15℃ temperature treatment while cv. ‘Huang-Hsin’ is more susceptible to high temperature stress, for good growth under 15/13℃. The relative growth rate (RGR) for ‘Hainan-Chin’ was highest at 46~60 DAS (days after sowing) and decreased along the growth period；also the RGR was reduced in 35/30℃ and 30/25℃. The result was similar to cv. ‘Huang-Hsin’. The rate of leaf formation was in a linear relationship with the temperature. Day/night temperature of 35/30℃ was detrimental to leaf formation. Growing under 20/15℃, cvs. ‘Hainan-Chin’ and ‘Huang-Hsin’ developed 7.2 and 7.0 leaves with an average rate of 0.8 and 0.7 leaves after every 10 days, respectively 84 days of sowing；The corresponding values obtained under 35/30℃were 5.8 and 5.0 leaves developed and at a rate of 0.5 and 0.3 leaves every 10 days, respectively. Various growth characteristics and leaf formation were higher at 15~22℃ for both varieties, it indicated the optimum temperature range for celery growth. Various reproductive growth characteristics were evaluated on seedling of 3 different ages (28, 42 and 56 d) either vernalized under 5℃ for 21 days or untreated before transplanting. Upon transplanting, the untreated control plants grew taller than other vernalized plants. However as the vernalized plants bolted later, there was no significant differences in plant height for all treatments at harvest, all plants grew to a height of 120~135㎝. There was no interaction of seedling ages and cultivars. Celery ‘Ching-Torng’ of 56d of age bolted ever under 20/15℃ before transplanting. Among the other three cultivars: ‘Huang-Hsin’ had the earliest bolting and flowering, followed by ‘Shii-Shu Late’, and ‘Hainan-Chin’ in that order. Thus, cv. ‘Huang-Hsin’ was the most sensitive to cold temperature and ‘Hainan-Chin’ had more low temperature requirement to be induced. Also ‘Hainan-Chin’ adapted the best with the largest plants, and highest total umbels. The younger seedlings (28d) responded less to vernalization than older seedlings (42b and 56d) after transplanting. This was determined by rate of stem elongation, time course to complete bolting and flowering, total umbels and dry matter percentage to flowers and seeds.

碩士<br>國立中興大學<br>園藝學系<br>82<br>Greenhouse and field experiments were conducted to study the influence of seedling ages (4、6、8 and/or 10 weeks) on growth and early yield of fresh-market tomato. Older seedlings in plug tray (20ml/plug) showed bigger plant size at transplanting in all three cultivars. The root specific activity of seedlings transplanted on November 17, 1993 increased after transplanting, but the root specific activity of 4 week old seedlings transpl- anted on December 2, 1993 were higher than other seedling. Four old seedlings transplanted on November 17, 1993 and December 2, 1993 had the best recovery from transplanting. There was no significanct difference on days to flowering of seedlings transplanted on December 4, 1993 and January 15, 1994 either among cultivars or among seedling ages. The first node of inflorescence(FNI) were not different among cultivars. There was a quardratic response of age upon FNI for seedlings transplanted on December 4, 1993 but the response was linear for seedlings transplanted on January 15, 1994."Known You 202" had the highest early yield for December 4, 1993 transplanting had the highest early yield for January 15, 1994 transplanting. Ten week old se- edlings had the highest early yield for both experiments transpl- anted on December 4, 1993 and on January 15, 1994. The diffreence between three planting seasons were also exam- ized. Seedlings transplanted on September 22, 1993 had the high- est plant height and leaf area. However, seedlings transplanted on November 17, 1993 had the highest number of nodes and leaves. The plant size of seedlings transplanted on December 2, 1993 were significantly smaller than seedlings transplanted in Sep- tember and November .

碩士<br>國立中興大學<br>園藝學系<br>84<br>SUMMARYFor producing bedding plants of Cockscomb（Celosia plumosa L. ''Castle''）, Periwinkle （Catharanthus roseus G. DON ''Orchid Cooler''）, Scarlet Sage （Salvia splendens F. SELLOW ex ROEM. ''Sizzler''） and Chinese Pink （Dianthus chinensis L. ''Snow Fire''）, the effect of seedling age in plug and the design of the jumbo cell pack style, which included cell size, density and bottom shape were studied.The suitable age of Cockscomb, Chinese Pink, Scarlet Sage or Periwinkle seedling in plug for transplanting was 4, 6, 8 or 8 weeks after sowing, respectively. The dimension of the cell pack for design was 48cm by 28cm.For producing Chinese Pink, Scarlet Sage, Cockscomb and Periwinkle bedding plant, the jumbo cell pack was composed thirteen 4"-pot, fifteen 3"-pot, eighteen 3"-pot and eighteen 2"-pot, respectively.The suitable style of cell bottom for Chinese Pink was four shender holes around the edge, for Scarlet Sage was four shender holes around the edge but the center without a hole, for Cockscomb was four shender holes around the edge and the center with a hole, or four fan shape holes, and for Periwinkle was four fan shape holes.

碩士<br>國立中興大學<br>園藝學系<br>90<br>Three cultivars of Pak-choi were sown in 72,128 and 288-cell plug trays, their plant fresh weight, dry weight, leaf number, leaf area, root fresh weight, root dry weight and root length showed no significant difference among different cell size after 9 to 12 days of sowing. However, the difference would increase gradually as days after sowing increased. Seedlings in 72-cell plug showed best growth. The root shoot ratio of cultivar ‘Dai Tokyo’ in 288-cell was higher than seedlings sowed in 72 and 128 cell plug. Relative growth rate of fresh weight and dry weight had the highest value in early seedling growth, but gradually increased as sowing days increased. Plants sowed in 288-cell showed less in relative growth rate at 21 days after sowing in comparison to seedlings in 72 and 128-cell but difference become less in later growth. Testing of root vigor indicated that seedling in 128-cell had higher TTC in fresh weight unit and seedlings in 72-cell were the lowest. Using PI value for measuring vigor affected by seedling age and cell size in plant growth after transplanting showed that both plants in 128 and 72-cell had higher PI value than the 288-cell. There were significant difference among cultivars, seedling age and cell size on fresh weight, dry weight, leaf number and plant height after transplanting into field. Cultivar ‘Feng Jing’ had the highest shoot fresh weight, dry weight and plant height. Among seedling age of 12, 15 and 18 days, the higher seedling age of the 18 day seedling had the best growth after transplanting. Plants in difference cell size showed that 72-cell plug seedling had the best shoot fresh weight, dry weight, leaf number and plant height, but the 4-unit of 128 cell was the lowest. Plants in 18-cell plug showed lower growth rate at 12 days after transplanting but growth rate increased with number of planting days. It was only less than plant in 72-cell when harvested at the 18th day. Relative growth rate after transplanting was highest in cultivar ‘To Pak-choi’ or those directly transplanting from 128-cell plug and 18 day seedling were lower in early growth than increased later which indicated that young seedlings had higher vigor. There were significant differences on fresh weight of the largest leaf, leaf area, position of leaf among cultivars, seedling age and plug size. The single leaf fresh weight and leaf area were positive correlated with single plant fresh weight which can be used as index for predicting yield.

碩士<br>國立中興大學<br>園藝學系所<br>97<br>This experiment mainly researches in the influences of growth of Impatiens walleriana ‘Acce Coral’on the different plug cell and seedling age, and in the probe into the biological response and the hazard factor of the plug seedling, and in the attempt, through simulating dark transport, to find out the feasibility to reduce the damage from the transport stress to Impatiens Walleriana by utilizing the chemical pretreatment prior to the transport. Plug seedling with different plug cell and seedling age, in the early growth of week four and five, the plant height, the weights of fresh and dry of both the shoot and roots growth better in round-square shape, but in week seven, the growth has no obvious difference among each plug cells. The seedling index of plug seedling has no significant change in week four and five, but it increases quickly in week six and has little difference from week seven. The root activity decreases along with the increase of the growth weeks; There is no obvious variation among the different plug cells. Plug seedling, after two, four and six days of simulating dark transport; along with the increase of the dark days, improves the respiration rate and ethylene production. The root activity drops from the control group of 2.95 O.D./g FW to 0.78, 0.94 and 0.95 O.D./g FW respectively. The root activity has a noticeable trend to go down with day four of the dark treatment. The contents of the chlorophyll a, the chlorophyll b and the total chlorophyll of the leaf blade under the first node of the stem drop apparently in day six, and there is no obvious difference among plug cells; the content of the chlorophyll of the leaf blade under the second node of the stem drop apparently in day four of the dark days. Through the dark transport, the leaf blade under the second node of the stem, compared to that of the first node, has lower content of the chlorophyll. The growth of the plug seeding, after the simulation of dark transport treatment for two, four and six days and transplanted for two weeks, has taller plant height with the four and six dark days treatment; however, the weights of fresh plant and dry plant the fresh root and dry root are lighter than the control group. After the dark treatment and transplanted, there is no big variation in the content of the chlorophyll among treatments. Potted Impatiens Walleriana, treated with plant growth retardants or antitranspirant prior to the simulation of dark transport treatment, cannot effectively reduce the ethylene production. While the days of transport increases, the ethylene production also grows; and it results in the decrease of the chlorophyll and root activity, and leads to the serious abscission of flower buds and 20% reduction in diameter of flowers.

博士<br>國立臺灣大學<br>農業化學研究所<br>89<br>Storage of seeds under adverse conditions results in the production of "aged "seeds exhibiting reduced grain viability and vigour. The precise causes of seed vigour loss and recovery are still unknown. In order to answer these questions, acceleratedly aged mung bean (Vigna radiata) seeds were used to investigate aging of mung bean seeds at various stages by incubating mung bean seeds at different temperature and relative humidity for various time intervals. The acceleratedly aged seeds exhibited a sigmoidal germination (%)-versus-time curve comparable to the theoretical natural aging curve. Accelerated aging significantly inhibited seed germination and seedling growth, resulting in an increase of the conductivity of seed exudation, decrease in viability and vigor, and higher ethylene production. A differentially expressed 1.2 kb cDNA fragment was isolated from imbibed acceleratedly aged seeds using mRNA differentially display technique. We obtained a full-length cDNA, named VrRH1 (Vigna Radiata RNA Helicase 1), by RACE method based on the 1.2 kb sequence. VrRH1 contains an open reading frame of 2139 bp encoding a protein of 713 amino acids and has seven highly conserved motifs including the DEAD-box as in the case of other plant RNA helicases. VrRH1 was sub-cloned into an expression vector pET-28b (+), over-expressed in E. coli BL 21 and purified by a Ni2+-Agarose column. The expressed protein showed double-stranded RNA unwinding and ATPase activities. Either ATP or dATP is required for the unwinding activity, indicating that VrRH1 is an ATP/dATP-dependent RNA helicase. The ATPase of VrRH1 has pH and temperature optima at 8.5 and 45℃, respectively. The ATPase activity of VrRH1 was not stimulated by the presence of synthetic polynucleotides. Northern blot analysis was performed using the 1.2 kb cDNA as a probe to analyze the expression of VrRH1（VrRH） mRNA in aged and non-aged mung bean seeds. The expressions of VrRH1 in 9-d-aged seedlings are higher than control seedlings. In different aging treatment, VrRH1 has the highest expression level in 12-d-aged seedlings. Besides, imbibed aged-seeds with longer axis showed higher level of VrRH1（VrRH）expression. Northern blot analysis of VrRH1 transcripts in different parts of mung bean showed that axis had higher expression than cotyledon using the full-length cDNA as a probe. There was a little amount of VrRH1 transcripts in newborn leaves, mature leaves and flowers. After accelerated aging treatment, mung bean seeds were imbibed for 16 to 32 hours and the expressions of VrRH1 were analysed at various time intervals of imbibition. The amount of VrRH1 transcripts reached a maximum in 24-hour-imbibed seeds. The accumulation of VrRH1 transcripts was shown to correlate the appearance of 25S and 18S rRNAs in the imbibed aging mung bean seeds. The results suggest that VrRH1 may play a role in the viability of mung bean seeds. It was also shown that seeds obtained from 9-d-12-h plants survived better than the control seeds. Purified His-VrRH1 was used as the antigens to prepare antisera for immunological studies. VrRH1 proteins were immunolocalized in longitudinal sections from 3-day- germinating accelerated aged seeds. Preliminary results show that VrRH1 proteins were expressed in the shoot apical meristem (SAM) of mung bean seedlings. We suggest that VrRH1 may play a role in regulating the growth and development of mung bean seedlings. Identification of the natural substrate of VrRH1 may provide further insight into its physiological function. Attempts were also made to isolate the native protein of VrRH by ammonium sulfate precipitation and cation exchange chromatography. The partially purified native VrRH had ATPase activity.

The nutrient use efficiency (NUE) of crops is typically low, in particular referring to the uptake of nutrients applied through fertilizers. A strategy to improve the NUE could be the development of new and more efficient fertilizers. A promising field in order to achieve this goal could be the use of nanotechnology. Nanomaterials are widely used in medical and pharmaceutical fields, but their application in agriculture and in particular in plant nutrition is at its infancy. A continuous method of FePO4 nanoparticles (FePO4 NPs) synthesis based on the extremely fine and rapid mixing of a FeCl3 solution with a K2HPO4 solution in a mixing chamber was tested for its effectiveness with a laboratory-made system. The proof-of-concept could produce FePO4 particles smaller than 100 nm, reaching the threshold of 50% of particles smaller of 100 nm, a value that is recommended by the European Union for the definition of nanomaterial. A pilot plant for the continuous FePO4 NPs synthesis was set up, using two dosing pumps for solutions pumping, and an HPLC mixing tee as mixing chamber. The system could produce 15 L•h-1 of raw FePO4 NPs suspension. Purification through dyalisis was optimized, together with a stabilization method of FePO4 NPs, called citrate capping, based on the adding of tribasic potassium citrate and thorough vortexing, in order to reduce aggregation and sedimentation of particles on long time periods. FePO4 NPs were then tested for their effectiveness as source of P and Fe on two hydroponically grown crop species, cucumber (Cucumis sativus) and maize (Zea mays). The experiments were designed in order to evaluate the effect of FePO4 NPs as source of both nutrients, or source of sole P and Fe. For this reason, as negative controls were used plants grown without P (-P), without Fe (-Fe), or without both nutrients (-P-Fe). In addition, in order to analyze if the size of FePO4 particles could cause different effects on plants, we included in the experiment a treatment with non-nanometric FePO4 (bulk FePO4). The results showed that nano-sized FePO4 improved the availability of P and Fe, if compared to the non-nano counterpart, as demonstrated by SPAD indexes of leaves and the determination of nutrients concentrations in tissues. Transmission Electron Microscopy (TEM) observations on cucumber roots treated with FePO4 NPs revealed that these particles did not enter into the plant, suggesting as mechanism of delivery of nutrients the dissolution in the apoplast. Gene expression analysis of homologs of AtPHR1, a key regulator of the response to P starvation in Arabidopsis, revealed in cucumber an upregulation of Csa3M608690 in plants grown with FePO4 NPs. The transcriptional behavior of Csa1M024210, homologs of AtBTS, suggested that plants grown with both forms of FePO4 are, with respect of Fe, in good nutritional conditions thus confirming physiological parameters. For maize, the negative modulation of ZmFER-Like gene in response to all treatments suggested a minor role of this gene in the regulation of Fe homeostasis in this plant species, while the upregulation of ZmIRO2 in plants grown with both forms of FePO4 confirmed the sub-optimal nutritional state of the plants.