Nitrogen is essential to obtain high yields of winter wheat in south coastal British Columbia, which includes Vancouver Island and the lower Fraser Valley. An accurate recommendation for N application is required to keep input costs down for most economical returns and to limit environmental problems related to leaching of excess N. The questions are how much, when and which form of N should be applied to winter wheat. The general objective of this study is to improve our understanding of winter wheat growth and N uptake. This study monitors the soil N supply and characterizes the plant development, dry matter accumulation, and N uptake of winter wheat in South Coastal B.C.. Also, it compares the effectiveness of conventional and intensive crop N management and urea and ammonium nitrate sources of fertilizer N under intensive crop management. A series of field experiments was conducted in 1986-87 and 1987-88 with winter wheat to evaluate conventional and intensive N management in the area. Additionally, a N source study was carried out in the latter year to compare ammonium nitrate and urea. Soil N supply for winter wheat ranged from 52 to 151 kg N/ha through the two years of field experiments at five sites. Available N in the 0-50 cm soil depth varied from 10 to 100 kg N/ha through the growing season in the different treatments. An accurate estimate of N behavior involves N accumulation in the crop. During the early spring until harvest, the crop dry matter yield and N uptake patterns were plotted. The grain yields ranged from 4 to 9 t/ha for the conventional management (75 kg N/ha), and from 4 to 11 t/ha for the intensive crop management (I.CM. 225 kg N/ha) system. Between the conventional and I.CM., there was no significant difference in grain yield but there was in quality, specifically grain protein. Grain protein ranged from 8.2 to 9.7% for the conventional and from 10 to 13.7% for the I.CM. treatment. Also, there was no difference in grain yield or quality between ammonium nitrate and urea fertilized plots at final harvest. However, in the early stage at GS31, crop took up more N from ammonium nitrate (97 kg N/ha) than from urea (75 kg N/ha) and soil mineral N levels with urea were higher than with ammonium nitrate. / Land and Food Systems, Faculty of / Graduate

No description available.

Replicated field experiments were conducted in 1981-82 and 1982-83 on a State loam soil to determine if split spring N applications have possible yield advantages over single N applications for soft red winter wheat (Triticum aestivum L.). Treatments included a single and various split applications of 89. 6 and 134. 4 kg N/ha. These were applied at specific stages of wheat development. A control treatment was included to determine the contribution of indigenous soil N to grain yield and nitrogen uptake. Grain yields were increased by a split application of 134.4 kg N/ha (67.2 at G.S. 3.0 and 67.2 at G.S. 10.5) in 1982. No differences between grain yield for single and split N applications occurred in 1983. Yield levels averaged 6.25 and 7.21 Mg/ha for 1982 and 1983, respectively. Single N applications at G.S. 3.0 induced excessive tillering which was reflected in the higher number of tillers per m². Excessive tillering also resulted in increased lodging occurrence and reduced the harvest index. Increases in grain yield with split applications were attributed to greater photosynthetic efficiency in lower tiller densities of head-bearing tillers. Split N applications also improved the nitrogen and phosphorous economy of winter wheat, which is shown by increases in the nitrogen and phosphorous harvest indices for split applications of 134.4 kg N/ha in 1983. This resulted from an increase uptake of these nutrients during post-floral grain development. Analysis of the wheat tissue for N content at G.S. 5.0 indicates that tissue N levels reflect the amount of N applied. This suggest that tissue N analysis may be used to diagnose N deficiencies. / M.S.

A greenhouse experiment was conducted over a ninety day period to test the effect of different nitrogen fertilizer regimes and several application rates of compounds with gibberellin and cytokinin activity (GA4/7 and BA, respectively) on the growth and development of Pinus brutia var. eldarica. Nitrogen produced no significant effects and this was attributed to its abundance in the potting medium, to begin with. All levels of growth regulators used showed a highly significant effect on vegetative development. A reduction in root collar diameter, shoot elongation, needle nitrogen content and oven-dry weight, was observed, especially when the medium and high hormonal rates were used. Phytotoxicity increased with the increase in concentration of both chemicals. Ba induced a proliferation of adventitious buds along the stem of saplings, but this was accompanied with rapid new top growth and branching at the top only when BA was applied in conjunction with GA4/7.

Attempts at reforestation of many sites in the southwestern United States have repeatedly failed. Experience and research show that moisture stress is the primary cause of seedling mortality. Therefore, it is of utmost importance to produce planting stock for these areas that are as drought tolerant as possible. Seedlings with high ratios of root mass to shoot mass and adequate mycorrhizal infections should be more resistant to harsh conditions than most seedlings currently produced in nurseries and greenhouses. Inferences from other research indicated that the root-shoot ratios of seedlings could be increased solely by decreasing the amount of nitrogen supplied to them. Mycorrhizal formation would also be enhanced by minimal nitrogen levels. Containerized ponderosa pine seedlings (Pinus ponderosa Lawson var. scopulorum Engelm.) were grown in commercial greenhouses at various levels of nitrogen fertilization and treated with several mycorrhizal inoculums. Mycorrhizal treatments significantly increased shoot height and diameter, but no other seedling parameters. The inoculums did not affect the root-shoot ratio or the percent of short roots that became infected. Nitrogen levels significantly affected all parameters measured. As nitrogen concentration increased, shoot height, diameter, and weight increased, while root weight, root-shoot ratios, and mycorrhizal infections decreased. The inverse relationship between fertilizer nitrogen concentration and the resulting root-shoot ratios of the seedlings was linear and highly correlated. Nitrogen and percent mycorrhizal infection was nearly linear and also inversely correlated. The results of this research are immediately applicable to current greenhouse and nursery operations. When stock is to be planted on sites where seedling survival may be compromised by harsh environmental conditions, production methods should be modified to yield seedlings with maximum root-shoot ratios and heavily infected with mycorrhizae.

Abstract can be viewed in PDF document. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.

Orientador: Juliano Carlos Calonego / Coorientador: Emanoel Gomes de Moura / Banca: João Paulo Gonsiorkiewicz Rigon / Banca: Gustavo Pavan Mateus / Banca: Iraê Amaral Guerrini / Banca: Emerson Guerrini / Resumo: Nas proximidades da região amazônica, trópico úmido maranhense, sobretudo na região centro norte do Estado, há condições edafoclimáticas que divergem de outras regiões do Brasil e impossibilitam o avanço da agricultura. A elevada pluviosidade somada às altas temperaturas em solos altamente intemperizados, predispostos a coesão e de baixa fertilidade natural dificultam o uso de técnicas comuns tais como aração e gradagem, uma vez que estas compactam ainda mais o solo impedindo o crescimento das raízes das culturas e a absorção dos nutrientes. Neste sentido, dois experimentos foram conduzidos em sistema de plantio direto na palha de leguminosas arbóreas em aleias no município de Brejo - MA e avaliados nos anos de 2016 e 2017. O solo de ambas as áreas foi classificado como Latossolo Amarelo Distrocoeso. Foi cultivado a cultura do milho nos dois experimentos e nos dois anos estudados. O objetivo do primeiro experimento foi avaliar a influência da cobertura do solo com a leguminosa arbórea Gliricidia sepium sobre a fertilidade do solo, o estímulo ao acúmulo de carbono orgânico do solo, a eficiência agronômica e de recuperação do nitrogênio e produtividade da cultura do milho. No segundo experimento, o objetivo foi avaliar o efeito da matéria orgânica sobre os atributos físico-químicos do solo, sequestro de carbono e os fatores que interferem na produtividade da cultura do milho. Observou-se que o uso de biomassa de leguminosas arbóreas como cobertura do solo associada a fertilizaç... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the vicinity of the Amazonian region, humid tropical Maranhão, especially in the central north of the state, there are edaphoclimatic conditions that diverge from other regions of Brazil and make it impossible to advance agriculture. The high rainfall combined with the high temperatures in highly weathered soils, predisposed to cohesion and low natural fertility make it difficult to use common techniques such as Ploughing and Harrowing since they further compact the soil, preventing the growth of the roots of the crops and absorption of nutrients. In this sense, two experiments were conducted under no - tillage system in the tree legume straw in alley cropping in the municipality of Brejo - MA and evaluated in the years 2016 and 2017. The soil of both areas was classified as Utisol. The maize crop was grown in both experiments and in the two years studied. The objective of the first experiment was to evaluate the influence of soil cover with the leguminous tree Gliricidia sepium on soil fertility, the stimulation of soil organic carbon accumulation, agronomic and nitrogen recovery efficiency and maize crop productivity. In the second experiment, the objective was to evaluate the effect of organic matter on soil physical-chemical attributes, carbon sequestration and factors that interfere in maize crop productivity. It was observed that the use of biomass of tree legumes as soil cover associated with fertilization via inorganic fertilizers increased soil carbon sequestration and the agronomic and nitrogen recovery efficiency. In addition, the addition of legume biomass to the soil resulted in improvements in the physical-chemical attributes of the soil and increased productivity of the maize crop. These conservationist systems of soil management allow to intensify production,minimize soil degradation and promote the sustainability of agriculture in the humid tropics / Doutor

Chan Hiu-ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 97-112). / Abstracts in English and Chinese. / Thesis Committee --- p.i / 摘要 --- p.ii / Abstract --- p.iii / Acknowledgements --- p.v / Abbreviations --- p.vi / Table of Contents --- p.vii / List of figures --- p.xi / List of tables --- p.xiii / Chapter Chapter 1 --- Literature Review --- p.1 / Chapter 1.1 --- Nitrogen assimilation in plants --- p.1 / Chapter 1.2 --- Importance of asparagine in plants --- p.5 / Chapter 1.3 --- Enzymatic reaction of asparagine synthetase (AS) --- p.8 / Chapter 1.4 --- Asparagine synthetase of non-plant organisms --- p.10 / Chapter 1.5 --- Biochemistry background of plant asparagine synthetases --- p.12 / Chapter 1.6 --- Molecular studies of asparagine synthetase genes in plants --- p.15 / Chapter 1.7 --- Arabidopsis thaliana as a model plant --- p.24 / Chapter 1.8 --- ASN studies in Arabidopsis thaliana --- p.24 / Chapter 1.9 --- Hypothesis --- p.27 / Chapter Chapter 2 --- Materials and Methods --- p.29 / Chapter 2.1 --- Chemicals --- p.29 / Chapter 2.2 --- Plant materials and growth conditions --- p.29 / Chapter 2.2.1 --- Surface sterilization of Arabidopsis seeds --- p.29 / Chapter 2.2.2 --- "Growth conditions of Arabidopsis seeds for total RNA extraction, enzyme assay, chlorophyll content measurement and dry weight measurement" --- p.30 / Chapter 2.3 --- Agrobacterium mediated transformation via vacuum infiltration method --- p.30 / Chapter 2.3.1 --- Principles --- p.30 / Chapter 2.3.2 --- Plant materials and bacterial strains of Agrobacterium mediated transformation --- p.31 / Chapter 2.3.2.1 --- Plant materials --- p.31 / Chapter 2.3.2.2 --- Gene constructs --- p.31 / Chapter 2.3.2.2 --- Bacterial strains --- p.32 / Chapter 2.3.3 --- Agrobacterium mediated transformation via vacuum infilitration --- p.32 / Chapter 2.4 --- Screening of transformants --- p.33 / Chapter 2.5 --- DNA and RNA manipulation --- p.34 / Chapter 2.5.1 --- DNA extraction and quantitation --- p.34 / Chapter 2.5.2 --- PCR amplification and detection of transgenes --- p.36 / Chapter 2.5.2.1 --- PCR amplification and detection of transgenes --- p.36 / Chapter 2.5.2.2 --- Primer sequence --- p.37 / Chapter 2.6 --- RNA analysis of transormants --- p.38 / Chapter 2.6.1 --- General introduction --- p.38 / Chapter 2.6.2 --- RNA extraction --- p.39 / Chapter 2.6.3 --- Making single-strand DIG PCR probes --- p.40 / Chapter 2.6.4 --- Quantitation of single-strand DIG-labeled probes --- p.42 / Chapter 2.7 --- Northern blot analysis --- p.42 / Chapter 2.7.1 --- Detection --- p.43 / Chapter 2.7.2 --- Film development --- p.43 / Chapter 2.8 --- "Amino acid, protein, dry weight and total nitrogen analysis" --- p.43 / Chapter 2.8.1 --- Extraction of free amino acids --- p.43 / Chapter 2.8.2 --- Protein assay --- p.44 / Chapter 2.8.3 --- Determination of nitrogen and carbon content in seeds --- p.45 / Chapter 2.8.4 --- Dry weight measurement --- p.45 / Chapter 2.8.5 --- Seed storage protein analyses --- p.45 / Chapter 2.8.6 --- Detection of chlorophyll content --- p.46 / Chapter 2.9 --- Asparagine synthetase activity analysis --- p.46 / Chapter 2.9.1 --- Crude extracts preparation --- p.46 / Chapter 2.9.2 --- AS enzyme assay --- p.47 / Chapter 2.9.3 --- Asparagine content measurement --- p.47 / Chapter 2.10 --- In situ hybridization --- p.48 / Chapter 2.10.1 --- Making cRNA probe --- p.48 / Chapter 2.10.2 --- In situ hybridization --- p.48 / Chapter Chapter 3 --- Results --- p.50 / Chapter 3.1 --- Construction of ASN1 overexpressing lines --- p.50 / Chapter 3.2 --- Changes in nitrogen status during vegetative growth of ASN1 overexpressing lines --- p.53 / Chapter 3.3 --- Changes in nitrogen status during seed development of ASN1 overexpressing lines --- p.55 / Chapter Chapter 4 --- Discussion --- p.76 / Chapter Chapter 5 --- Conclusion --- p.85 / Chapter Chapter 6 --- Perspective --- p.86 / Appendix --- p.87 / References --- p.97

Orientador: Ciro Antonio Rosolem / Banca: Rogerio Peres Soratto / Banca: Monica Sarolli Silva de Mendonça Costa / Banca: André Cesar Vitti / Banca: Paulo César Ocheuze Trivelin / Resumo: O conhecimento de como o manejo do solo influencia na dinâmica do nitrogênio (N) em longo prazo pode fornecer bases para desenvolver sistemas de produção que otimizem a ciclagem deste nutriente. Objetivou-se com este trabalho avaliar o efeito de sistemas de manejo, com plantas de cobertura e escarificação, em rotação com a cultura da soja, no balanço e ciclagem do N e na produtividade da soja. O experimento vem sendo conduzido desde 2003, em um Nitossolo Vermelho distroférrico, estruturado, de textura argilosa. O experimento foi delineado em blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram constituídas pelas culturas de inverno triticale (X Triticosecale) e girassol (Helianthus annuus), e as subparcelas pelos manejos de primavera, milheto (Pennisetum glaucum), sorgo forrageiro (Sorghum bicolor) e crotalária júncea (Crotalaria juncea), além da escarificação, que foi realizada em 2003 e 2009, também na primavera. Na safra de verão foi cultivada a soja (Glycine max), em todas as subparcelas. A ciclagem e o balanço do N foram estudados por determinações de N-total e estoque de N no solo, massa de matéria seca e acúmulo de N da palhada e da parte aérea das culturas, produtividade e exportação de N pelas culturas de outono/inverno e da soja, saídas de N por lixiviação de NO3- e emissão de NH3 e N2O, além da quantificação das entradas de N no sistema via deposição atmosférica, pulverização de defensivos e sementes. As saídas de N oscilaram entre 1,2 a 3,3, 8,2 a 8,9 e 12,2 a 50,4 kg ha-1 ano-1 para emissão de N2O, volatilização de NH3 e lixiviação de NO3-, respectivamente. As culturas de outono/inverno pouco se diferenciaram na ciclagem de N no sistema solo-planta. Os manejos de primavera se diferenciaram mais na lixiviação de NO3-. Apesar de a crotalária apresentar maior perda de N por lixiviação, devido ao ... / Abstract: The knowledge of how soil management acts upon N cycling in long term can provide bases to develop crop production systems that optimize the cycling of this nutrient. The objective of this research was to assess the effect of soil management systems, using cover crops and chiseling in rotation with soybean on N cycling and balance. The experiment has been carried out since 2003, on a clayey Rhodic Nitosol. The experimental design was a randomized complete block design, in a split‑plot arrangement, with four replicates. Plots consisted of the fall-winter crops, triticale (X Triticosecale) and sunflower (Helianthus annuus), and subplots of the spring managements, pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor) and sunn hemp (Crotalaria juncea), besides chiseling in 2003 and 2009, at the spring too. Soybean (Glycine max) was grown in the summer. The N cycling and balance were studied by determinations of soil total-N and N storage, dry mass and N accumulation of crops and its residues, grain yield and N exportation by fall-winter crops and soybean, N outputs by NO3- leaching and NH3 and N2O emission, besides N inputs by atmospheric deposition, pesticide spraying and seeds. Losses of N ranged from 1.2 to 3.3, 8.2 to 8.9 and 12.2 to 50.4 kg ha-1 year-1 as N2O, ... / Doutor

Graduation date: 1991