Orientadora: Eliana Gertrudes Macedo Lemos / Banca: Miguel Luiz Menezes Freitas / Banca: Haroldo Alves Pereira Junior / Banca: Jackson Antonio Marcondes de Souza / Banca: Cristina Lacerda Soares Petrarolha Silva / Resumo: O amendoim (Arachis hypogaea L.) faz parte da família Fabaceae, que é capaz de associar-se com bactérias do gênero Rhizobium. Em solos onde o amendoim é cultivado tem-se a presença de uma população autóctone desta bactéria. A necessidade de inoculação das sementes de amendoim em solos contendo população autóctone tem sido sempre discutida. Com o objetivo de avaliar o efeito da inoculação de sementes de amendoim cultivado em vasos contendo vermiculita e a interação existente entre microrganismo-planta e microrganismo-microrganismo, foi realizado um experimento sob cultivo em casa de vegetação, em vasos de 0,5 L, com o cultivar IAC 886 e a IAC Tatu-ST, com três repetições. Os tratamentos foram constituídos de aplicação dos isolados individualmente e combinados com a estirpe padrão tipo SEMIA 6144, Bradyrhizoibium sp., recomendada pelo Ministério da Agricultura e sem aplicação de inoculante, sem aplicação de qualquer isolado. Houve interação entre o tipo de plantio e a aplicação de inoculante para todas as variáveis analisadas. Para a massa de matéria seca da parte aérea houve uma diferença significativa. O variável número de nódulos e o teor de Nitrogênio também apresentam diferenças quanto à aplicação, sendo que, em todos os casos foram superiores ao controle sem aplicação com os isolados nativos. / Abstract: Peanut (Arachis hypogaea L.) belonging to Fabacea family, is able of associating with bacteria from Rhizobium genus. In soils where peanut is grown, there is usually an autochthonous population of these bacterial, however, the need of inoculation in peanut seeds in soils containing autochthonous population has always been controversial subject. With the objective of evaluating the effects of peanut seeds inoculation cultivated in vases contend vermiculite and to verifying the interaction with plant regulators, an experiment was carried out in greenhouse conditions, with three repetitions containing Runner IAC 886 e IAC Tatu-ST cultivar. The treatments were constituted of application of the individually isolated and combined with the lineage standard Bradyrhizobium sp., SEMIA 6144, recommended by Bureau of the Agriculture. An interaction was observed between the type of plantation and the application of inoculants for all analysed variable. For the mass of dry matter of the aerial part it had a significant difference. The variable numbers of nodules and rate of Nitrogen also present differences related to the treatments, being that, in all the cases was greater to the control without application of the isolated natives. / Doutor

Master of Science / Department of Plant Pathology / Revathi Govind / Clostridium difficile, a gram-positive, anaerobic bacterium, is a major cause of antibiotic-related diarrhea and pseudomembraneous colitis. In the last decades, C. difficile has emerged as a major threat because of its tendency to cause frequent and severe disease. Because of the severity of the infection and its high rate of recurrence, there is a significant financial burden on healthcare systems. Antibiotic treatments are a primary risk factor for the development of C. difficile infection because they disrupt the normal gut flora in the host, enabling the antibiotic resistant bacterium to colonize the colon. Most of the resistance mechanisms in C. difficile reported to date can be classified as either antibiotic-degrading enzymes or modification of target sites. Another mechanism that can contribute to antibiotic resistance in C. difficile is the extrusion of antimicrobial compounds by efflux pumps. The goal of this project was to provide initial insights into the roles and mechanisms of a putative efflux pump complex. To do this, a number of experiments were designed to provide information about the structures, localization, and functions of this protein complex. It was determined that acidic pH conditions and a small number of antimicrobials, including inorganic compounds, organic compounds, fungicides, and antibiotics, inhibit growth of a C. difficile mutant lacking this pump system. Interestingly, higher NaCl in the medium and alkaline pH seem to promote the growth of a C. difficile mutant lacking this pump or, surprisingly, only inhibit growth of the wild type strain. The experiments performed in this project suggest that this efflux pump might have an essential role in C. difficile physiology, possibly by serving as an efflux pump for toxic metabolites.

Cloning and molecular characterization of new genes constitutes a useful approach in studying the symbiotic interactions between the model plant Medicago truncatula and Synorhizobium meliloti. Large numbers of expressed sequence tags (ESTs) available for Medicago truncatula, along with numerous cDNA, oligonucleotides, and Affimetrix DNA microarray chips, represent useful tools for gene discovery. In an attempt to identify a new gene that might be involved in the process of nodulation in Medicago truncatula, preliminary data reported by Fedorova et al. (2002), who identified 340 putative gene products or tentative consensus sequences (TCs) expressed only in nodules, was used. This research was focused on TC33166 (TC103185), which has 3 ESTs in the TC, and whose strongest BLASTX hit of TC103185 is the incomplete root hair elongation (IRE) protein kinase-like protein (NP_192429) from Arabidopsis thaliana. The Arabidopsis IRE gene is required for normal root hair growth, and a role in apical growth was suggested (Oyama et al., 2002). Infection thread growth can be looked at as an inward growth of the root hair. Thus, TC103185 was a good candidate for identifying a gene that may be involved in early events of nodulation. MtIRE (GenBank accession AC122727) is organized in 17 exons and 16 introns, similarly to the Arabidopsis IRE gene. MtIRE is a new member of the IRE family and it is a putative Ser/Thr protein kinase. MtIRE is a nodule- and flower-specific gene, suggesting that nodulation may have recruited it from other developmental processes. MtIRE is likely to be involved in the invasion process, or in the maturation of the symbiosome, or of the cells that contain rhizobia, rather than infection thread initiation and elongation or in nitrogen fixation. Nodule invasion precedes the onset of MtIRE expression and the expression pattern changes in time within the nodule. RNA interference results support MtIRE expression data and suggest a possible role in preventing extensive defense responses. Our study demonstrates the existence of an Arabidopsis IRE homolog in Medicago truncatula root nodules with an entirely new function and regulation.

<p> Sinorhizobium meliloti is an alpha-proteobacterium that forms symbiotic nodules on the roots of Medicago sativa (alfalfa). The ability to catabolize specific compounds available in the soil is one of the best-characterized factors to increase competition for nodulation. In order to successfully attain symbiosis S. meliloti must compete for nutrients in the rhizosphere, which can be done by having a large number of transport systems encoded in its genome. Genes encoding proteins involved in transport constitute the largest (12%) class of genes in the S. meliloti genome. Great interest now lies in determining substrates for the transport systems and their role in the survival and fitness of S. meliloti.</p> <p> An estimated 824 transport genes in the genome of the soil bacterium Sinorhizobium meliloti are predicted to encode 382 transport systems. All of the S. meliloti transporters had been studied under 120 different conditions, including growth on various carbon and nitrogen sources, seed and root exudates and starvation conditions.</p> <p> From this screen of every transport system in S. meliloti, the substrates that induce expression of over 50 transport systems have been identified. We have found putative transporters for amino acids, sugars, sugar alcohols, amino sugars, betaines and other compounds that might be found in the soil. This large scale expression analysis gives insight into the natural environment of S. meliloti by studying those genes that are induced by compounds that would be found in the soil.</p> / Thesis / Master of Science (MSc)

Le but du projet est de mettre au point de nouveaux outils enzymatiques permettant la production de chitinoligosaccharides de taille et de degré d'acétylation parfaitement contrôlés pour l'étude d'enzymes impliquées dans la biosynthèse, la biodégradation et la modification de la chitine, et pour l'étude de récepteurs protéiques d'origine animale ou végétale. Des études récentes ont montré que les oligomères de la chitine et leurs dérivés sont des molécules qui interviennent dans les phénomènes symbiotiques et de reconnaissance hôte-pathogène dans le règne végétal. Ces molécules sont utilisées en agrochimie comme biofertilisants, et potentiellement en phytosanitaire. Ils sont connus également pour posséder de nombreuses activités biologiques dans le domaine de la santé (effets antimicrobiens, anticancéreux, anti-inflammatoires, immunostimulants...). Si les activités de cette classe d'oligosaccharides sont parfaitement reconnues, leurs modes d'actions restent encore à éclaircir, ce qui nécessite de disposer de molécules pures aux structures chimiques parfaitement contrôlées. La production d'oligomères de la chitine nécessite traditionnellement la mise en œuvre d'une chimie fastidieuse, qui peut être facilitée par une approche chimio-enzymatique.Dans le cadre de cette thèse, nous souhaitons donc développer des outils enzymatiques permettant la synthèse d'une bibliothèque de molécules de taille et de degré d'acétylation contrôlés en vue d'études structure-activité biologique. Pour cela, nous chercherons à produire des N-désacétylases et des chitinases dans différents systèmes d'expression et à caractériser leur activité afin de générer une panoplie de molécules de structure moléculaire parfaitement définie à partir de fragments saccharidiques issus de la biomasse. Les molécules ainsi préparées pourront ensuite être modifiées de façon chimio-sélective afin d'obtenir des sondes photoactivables et/ou biotinylées pour la caractérisation de récepteurs, des substrats fluoro- ou chromogéniques pour le dosage spécifique d'activités enzymatiques ou encore des lipochitinoligosaccharides capables de favoriser la croissance des plantes. Les approches utilisées pour mener à bien ce projet pluridisciplinaire seront : l'ingénierie et la production de protéines recombinantes, la caractérisation biochimique d'activités enzymatiques ainsi que la synthèse chimio-enzymatique et la modification chimique d'oligosaccharides qui devront être caractérisés d'un point de vue physicochimique. Il s'agit d'un projet intégré dans une collaboration nationale financée par l'ANR réunissant des équipes de l'Université de Grenoble, de Lyon, d'Orsay, et l'entreprise Bayer CropScience. / The aim of the project is to develop new tools for enzymatic production of chitooligosaccharides size and degree of acetylation perfectly controlled for the study of enzymes involved in biosynthesis, biodegradation and modification of chitin and for the study of protein receptors of animal or vegetable origin. Recent studies have shown that oligomers of chitin and its derivatives are molecules involved in the phenomena of symbiotic and host-pathogen recognition in plants. These molecules are used as agrochemicals biofertilizers. They are also known to possess numerous biological activities in the field of health (anti-microbial, anti-cancer, anti-inflammatory, immunostimulant ...). If the activities of this class of oligosaccharides are well recognized, their modes of action remain to be clarified, which requires having pure molecules with chemical structures perfectly controlled. The production of chitin oligomers traditionally requires the implementation of a tedious chemistry, which can be facilitated by a chemoenzymatic approach.As part of this thesis, we want to develop enzymatic tools for the synthesis of a library of molecules of size and degree of acetylation controlled studies for structure-biological activity. For this, we will seek to produce N-deacetylase and chitinases in different expression systems and characterize their activity to generate a variety of molecules well-defined molecular structure from saccharide fragments derived from biomass. The molecules thus prepared can then be modified so as to achieve chemoselective photoactivatable probes and / or biotinylated for the characterization of receptors, substrates or fluoro-chromogenic assay for specific enzyme activities or lipo-chitooligosaccharides can promote plant growth. The approaches used to complete this multidisciplinary project are: engineering and production of recombinant proteins, the biochemical characterization of enzymatic activities and chemoenzymatic synthesis and chemical modification of oligosaccharides to be characterized from the point of physicochemical view. This is an integrated project in a national collaboration funded by the ANR with teams from the University of Grenoble, Lyon, Orsay, and Bayer CropScience.

Master of Science / Department of Agronomy / Kraig Roozeboom / Nitrogen fixation by Bradyrhizobium japonicum in soybean [Glycine max] is highly beneficial in soybean crop production. Nodulation issues have been encountered on fields new to growing soybeans in recent years in Kansas. The purpose of this research was to evaluate soybean nodulation performance under various situations and seed handling practices in order to educate producers on how to achieve reliable nodulation consistency in the field. The objectives of the study were to: 1) compare inoculant products using single and double rates and in combination with one another on fields with varying soybean history; 2) determine if there was a negative interaction between inoculant products and common seed treatments; and 3) discover the influence of inoculated seed storage conditions before planting on the rhizobia’s ability to successfully nodulate soybean roots. Field experiments were conducted on diverse Kansas sites in 2011 and 2012. Inoculant treatment and seed treatment interaction trials had ten and seven experimental sites respectively. Inoculated seed storage conditions were evaluated in a greenhouse experiment during the spring of 2013. All studies used a randomized complete block design with four replications. The Novozymes inoculant products generally provided superior nodulation performance over other company products in the study where soybean had not been in recent rotation with an average increase of 167% in nodule number verses the control. The combination of dry and liquid inoculant products provided a significant increase in root nodule number at five of the environments out of recent rotation with a 76% increase over single inoculant rates. Although there were early season nodulation differences between treatments in new soybean ground, these did not carry through to seed yield differences in the majority of research sites. Hot and dry summer conditions reduced yields, making detection of treatment differences difficult. There were no negative effects on nodulation performance with any of the seed treatments. Although soybean seed yield was 634 kg ha[superscript]-[superscript]1 greater for the Novozyme combination treatment compared to the check at one location in 2011, the control yielded as well or better than all other treatment/inoculant combinations, implying that yield differences were likely not related to inoculant treatments. At other sites, yield was not influenced by seed treatment and inoculant combinations. Results indicate that seed treatment formulations did not significantly impact bacterial inoculant product performance, soybean nodulation, or yield. Storage conditions had no effect on nodulation performance in the greenhouse study, likely due to survival of Bradyrhizobium japonicum in the heat-treated growth medium.

O feijão caupi, através da simbiose com bactérias do gênero Bradyrhizobium, pode obter nitrogênio através do processo de fixação biológica do N2 (FBN). A nodulação e a FBN são influenciadas por fatores edafoclimáticos que podem trazer benefícios ou prejuízos ao processo. A disponibilidade de nutrientes está entre os principais fatores que influenciam a FBN e, dentre os principais nutrientes que influenciam tal processo, cita-se o fósforo.Objetivou-se com esse trabalho, avaliar o rendimento de cultivares de feijão caupi em função das estirpes fixadora de nitrogênio associada ou não a adubação fosfatada, no sul do estado do Tocantins em condições de casa de vegetação e em campo. Os experimentos foram conduzidos em casa de vegetação e a campo, um com a cultivar de feijão-caupi, BRS Nova Era e o outro BRS Sempre Verde, com 4 estirpes de rizóbio mais um tratamento sem bactéria, associadas ou não a 6 doses de fósforo.O delineamento utilizado foi em blocos casualizados, disposto em esquema fatorial 5 x 6. A campo os tratamentos foram dispostos em um delineamento experimental blocos casualizados sob arranjo fatorial 3 x 6, sendo o primeiro fator duas estirpes de rizóbio e um tratamento sem e o segundo fator seis doses de P2O5 com 4 repetições. As doses consistiram de 0, 30, 60, 90, 120 e 150 kg ha-1de P2O5, aplicadas na semeadura. As características avaliadas em casa de vegetação foram: altura de planta, diâmetro de colo, massa seca da parte aérea, massa seca das raízes, número de nódulos, massa seca dos nódulos. As características avaliadas em campo foram: clorofila total, massa seca da parte aérea, peso de cem sementes, produtividade e nitrogênio total na parte aérea. As estirpes estudadas associadas ou não as doses de fósforo proporcionaram acréscimo na altura de planta, diâmetro de colmo, massa seca da parte aérea, massa seca da raiz para as duas cultivares de feijão-caupi estudas BRS Nova Era e BRS Sempre Verde. Para os experimentos de campo a cv. BRS Sempre Verde a estirpe mais indicada é INPA 03-11B; para a cv. BRS Vinagre a estirpe BR 3299 foi mais eficiente. A dose de fósforo que condicionou a máxima eficiência agronômica variou de 70 a 110 kg ha-1. / Cowpea beans, through symbiosis with bacteria of the genus Bradyrhizobium, can obtain nitrogen through the biological fixation process of N2 (BNF). Nodulation and BNF are influenced by edaphoclimatic factors that can bring benefits or losses to the process. The availability of nutrients is among the main factors influencing BNF and, among the main nutrients that influence this process, phosphorus is cited. The objective of this work was to evaluate the yield of cowpea cultivars as a function of nitrogen fixing strains associated or not with phosphate fertilization, in the southern state of Tocantins under greenhouse conditions and in the field. The experiments were conducted in a greenhouse and in the field, one with the cowpea bean cultivar BRS Nova Era and the other BRS Sempre Verde with four strains of rhizobium plus a treatment without bacteria, associated or not To 6 doses of phosphorus. The experimental design was a randomized block design, arranged in a factorial scheme 5 x 6. In the field treatments were arranged in a randomized block design under a factorial arrangement 3 x 6, the first factor being two strains of rhizobia and A treatment without and the second factor six doses of P2O5 with 4 replicates. The doses consisted of 0, 30, 60, 90, 120 and 150 kg ha-1 of P2O5, applied at sowing. The characteristics evaluated in greenhouse were plant height, diameter of lap, dry mass of shoot, dry mass of roots, number of nodules, dry mass of nodules. The characteristics evaluated in the field were: total chlorophyll, shoot dry mass, weight of one hundred seeds, productivity and total nitrogen in shoot. The strains studied, whether or not associated with phosphorus doses, increased plant height, stem diameter, dry shoot mass, root dry mass for the two bean cultivars BRS Nova Era and BRS Sempre Verde. For the field-to-cv. BRS sempre verde the most indicated strain is INPA 03-11B; For cv. BRS Vinagre strain BR 3299 was more efficient. The dose of phosphorus that conditioned the maximum agronomic efficiency ranged from 70 to 110 kg ha-1.

Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-28Bitstream added on 2014-06-13T19:07:33Z : No. of bitstreams: 1 gazola_e_me_botfca.pdf: 515907 bytes, checksum: 147c1f8c1d57f0773041fffb27a91fd1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo do trabalho foi avaliar o desempenho de cultivares transgênicas de soja (Glycine max (L.) Merrill) em sucessão a culturas de inverno na implantação do sistema de semeadura direta. O experimento foi conduzido na área experimental do Departamento de Produção Vegetal, na Faculdade de Ciências Agronômicas/UNESP, Campus de Botucatu-SP, durante o ano agrícola 2006/07. O delineamento experimental utilizado foi o de blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram representadas por cinco espécies cultivadas no inverno, aveia branca (Avena sativa L.), nabo forrageiro (Raphanus sativus L.), cevada (Hordeum vulgare L.), trigo (Triticum aestivum L.) e ervilha forrageira (Pisum sativum L.) e área de pousio (vegetação espontânea). As subparcelas foram constituídas por seis cultivares de soja (BRS 243 RR, BRS 245 RR, BRS 247 RR, BRS 255 RR, BRS 256 RR e BRS 244 RR), cedidas pela Embrapa SNT-EN.LDB, totalizando 36 tratamentos. Foram avaliadas, nas espécies de inverno, a massa da matéria seca da parte aérea e a produtividade de grãos, enquanto na soja as características agronômicas como florescimento, ciclo, alturas de plantas e de inserção da primeira vagem, população final de plantas, grau de acamamento, número de vagens chochas, número de nódulos por planta, massa da matéria seca dos nódulos por planta, além dos componentes da produção número de vagens por planta, número de grãos por vagem, massa de 100 grãos e a produtividade. Foi avaliado, também, o teor foliar dos macronutrientes N, P, K, Ca, Mg e S das plantas de soja por meio da diagnose foliar.A cevada, entre as culturas de inverno, foi a que apresentou os maiores valores de produtividade de grãos e de massa de matéria seca, não diferindo, na ultima avaliação da aveia, da ervilha forrageira e do nabo forrageiro. As características... / The objective of this research was to evaluate crop yield and some characteristics and yield components of transgenic soybean cultivars sown after different winter cover crops in the first year under no tillage system. The present work was carried out on the experimental area of the “Departamento de Ciências Agronômicas”, “Faculdade de Ciências Agronômicas/UNESP”, Botucatu-SP, in 2006/2007, as a partnership with Embrapa SNT – EN.LDB (Embrapa serviços de negócios para transferência de tecnologia – Escritório de negócios de Londrina). The experimental design was the completely randomized block with split plots and four replications. The main plots consisted of five winter cover crops, white oat (Avena sativa L.), forage turnip (Raphanus sativus L.), barley (Hordeum vulgare L.), wheat (Triticum aestivum L.) and ground pea (Pisum sativum L.) and an area under fallow (spontaneous vegetation). The subplots consisted of six soybean cultivars (BRS 243 RR, BRS 245 RR, BRS 247 RR, BRS 255 RR, BRS 256 RR and BRS 244 RR) which were granted by Embrapa SNT-EN.LDB, totaling 36 treatments. Shoot dry matter and grain yield were evaluated for each winter crop. While the experiment had been carried out, some soybean agronomic characteristics were evaluated like flowering, cycle, first pod insertion and plant height, final population, bending, number of nodes per plant, nodes dry matter per plant and grain yield. Yield components, weight of 100 grains, number of pods and aborted grains per plant and grains per pod were evaluated. N, P, K, Ca, Mg and S levels in soybean tissue werealso evaluated through foliar diagnosis. Among all winter crops evaluated, barley was the one that showed higher values for grain yield and dry matter, however, it did not differ from oat, ground pea and forage turnip in the last evaluation. Variance analysis for agronomic characteristics... (Complete abstract click electronic access below)

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-05-02T19:07:13Z No. of bitstreams: 1 2014 - Rafael Sanches Pacheco.pdf: 1387070 bytes, checksum: c73e833c8d495bf472f647befeedd57e (MD5) / Made available in DSpace on 2018-05-02T19:07:13Z (GMT). No. of bitstreams: 1 2014 - Rafael Sanches Pacheco.pdf: 1387070 bytes, checksum: c73e833c8d495bf472f647befeedd57e (MD5) Previous issue date: 2014-08-19 / CNPq / The 15N natural abundance technique to measure the biological nitrogen fixation (BNF) in legumes is based on the slight enrichment of 15N observed in soils to the atmosphere and does not require the application of labelled fertilizers. The objectives of this work were: to quantify the BNF contribution in common bean (Phaseolus vulgaris) cultivars under field conditions through the 15N natural abundance technique; to evaluate the agronomic performance of these cultivars under inoculation; to estimate the isotopic fractionation value during BNF (B value) of common bean cultivars grown in nutrient solution. Two experiments were conducted in greenhouse in nutrient solution without N, in the years 2012 and 2013 in Serop?dica, RJ. Three common bean cultivars were evaluated. Plant biomass was sampled at different growth stages, where the N natural abundance was analyzed. In 2012 experiment, the nodules showed positive ?15N, with deltas of 6.63? and 8.18? in Grafite and Radiante cultivars, respectively. The B value in shoot was ?0.919?, ?0.734? and ?0.724? for cultivars Grafite, Ouro Negro and Radiante, respectively. In 2013 experiment, the nodules showed great enrichment in 15N, with 9.11? and 8.36? deltas in Radiante and Grafite cultivars. The B value in shoot was -1.06? and -1.40? for cultivars Radiante and Grafite, respectively. The average B value in shoots of common bean cultivars was ?1.23?, and the B value of ?1.2 was used in the calculation of the BNF contribution in the field experiments of this study. Eight common bean cultivars were grown in field conditions in 2011 and 2012, with two N sources (inoculation with commercial inoculant with rizhobia or fertilization with 90 kg ha-1 of mineral N), with four replications, at Embrapa Rice and Bean in Santo Antonio de Goias, GO. Biomass of the shoot, root, nodules and grains were sampled, and total N and 15N natural abundance were analyzed in shoots and grains. In the experiment in 2011, the Ouro Negro cultivar produced higher nodule mass under inoculation, also at reproductive stages, and the Jalo Precoce and Radiante cultivars showed the lowest nodule mass. The grain yield of the eight cultivars was 1614 and 2942 kg ha-1 under inoculation or mineral N, respectively. Under inoculation, the Ouro Negro cultivar showed the highest N accumulation in shoots and grains and the highest grain yield, reaching 2200 kg ha-1, equivalent to 73% of yield under mineral N. In 2011, the N accumulation derived from BNF in grains of the eight cultivars ranged from 5.8 to 16.4 kg ha-1, which corresponded to a BNF contribution of 17% and 33% in Marfim and Ouro Negro cultivars, respectively. In 2012, the higher nodule mass occurred in Vereda and Estilo cultivars, in the first and second samples, respectively, whereas Radiante cultivar had the lowest nodule mass. The average grain yield of the eight cultivars was 3284 and 3919 kg ha-1 under inoculation and mineral N, respectively. The N accumulation derived from BNF in grains was 68.4, 38.7, and 21.6 kg ha-1 in Ouro Negro, Grafite and Radiante cultivars, respectively, corresponding to a BNF contribution of 49, 29 and 32%. The method of 15N natural abundance provided the identification of BNF potential for the supply of N in different common bean genotypes, arising as a tool for providing subsidies to guide breeding programs in order to increase BNF efficiency. / A t?cnica da abund?ncia natural de 15N para mensurar a fixa??o biol?gica de nitrog?nio (FBN) em leguminosas baseia-se no ligeiro enriquecimento de 15N observado nos solos em rela??o ? atmosfera e n?o exige a aplica??o de fertilizantes marcados. Os objetivos deste trabalho foram: quantificar, atrav?s da t?cnica da abund?ncia natural de 15N, a contribui??o da FBN em cultivares de feijoeirocomum (Phaseolus vulgaris) em condi??es de campo; avaliar o desempenho agron?mico dessas cultivares sob inocula??o; estimar o valor do fracionamento isot?pico durante a FBN (valor B) de cultivares de feijoeiro crescidas em solu??o nutritiva. Foram conduzidos dois experimentos em casa de vegeta??o, em solu??o nutritiva isenta de N, nos anos de 2012 e 2013, em Serop?dica, RJ. Foram avaliadas tr?s cultivares de feijoeiro, efetuando-se coletas de biomassa em diferentes est?dios e analisando-se a abund?ncia natural de 15N do material vegetal. No experimento em 2012, os n?dulos apresentaram ?15N positivo, com deltas de 6,63? e 8,18? nas cultivares Grafite e Radiante, respectivamente. O valor B da parte a?rea foi de ?0,92?, ?0,73? e ?0,72?, nas cultivares Grafite, Ouro Negro e Radiante, respectivamente. No experimento em 2013, os n?dulos apresentaram deltas de 9,11? e 8,36? nas cultivares Radiante e Grafite. O valor B da parte a?rea foi de ?1,06? e ?1,40? nas cultivares Radiantee Grafite, respectivamente. O valor B m?dio da parte a?rea das cultivares foi de ?1,23?, sendo o valor B de ?1,2 utilizado nos c?lculos da contribui??o da FBN nos experimentos de campo desse estudo. Oito cultivares de feijoeiro foram crescidas em condi??es de campo em 2011 e 2012, sob duas fontes de N (inocula??o com inoculante comercial com riz?bio ou aduba??o com 90 kg ha-1 de N mineral), com quatro repeti??es, na Embrapa Arroz e Feij?o, em Santo Antonio de Goi?s, GO. Foram efetuadas amostragens de biomassa de parte a?rea, raiz, n?dulos e gr?os e an?lises de N total e abund?ncia natural de 15N na parte a?rea e gr?os. No experimento em 2011, a cultivar Ouro Negro produziu maior massa de n?dulos sob inocula??o, inclusive nos est?dios reprodutivos, e as cultivares Jalo Precoce e Radiante apresentaram a menor massa de n?dulos. O rendimento m?dio de gr?os das oito cultivares foi de 1614 e 2942 kg ha-1 sob inocula??o ou N mineral, respectivamente. Sob inocula??o, a cultivar Ouro Negro apresentou os maiores ac?mulos de N na parte a?rea e nos gr?os e a maior produtividade, atingindo 2200 kg ha-1 de gr?os, equivalente a 73% da produ??o sob N mineral. Em 2011, o ac?mulo de N derivado da FBN nos gr?os das oito cultivares variou de 5,8 a 16,4 kg ha-1, que correspondeu a 17% e 33% de contribui??o da FBN nas cultivares Marfim e Ouro Negro, respectivamente. Em 2012, a maior massa de n?dulos ocorreu nas cultivares Vereda e Estilo, na primeira e segunda coletas, respectivamente, e a cultivar Radiante apresentou a menor massa de n?dulos. O rendimento m?dio de gr?os das oito cultivares foi de 3284 e 3919 kg ha-1 sobinocula??o e N mineral, respectivamente. O ac?mulo de N derivado da FBN nos gr?os foi de 68,4 kg ha-1 na cultivar Ouro Negro, 38,7 kg ha-1 na cultivar Grafite e 21,6 kg ha-1 na cultivar Radiante, que correspondeu a 49, 29 e 32% de contribui??o da FBN, respectivamente. A t?cnica da abund?ncia natural de 15N possibilita a identifica??o do potencial de FBN para o fornecimento de N em diferentes gen?tipos de feijoeiro, e mostra-se como uma ferramenta capaz de fornecer subs?dios para orientar os programas de melhoramento da esp?cie, visando aumentar a efici?ncia da FBN.

Thesis (M.Sc. (Agronomy )) --University of Limpopo, 2007 / Intercropping is the growing of two or more crops simultaneously on the same field, and it is a common traditional practice among resource-poor farmers throughout the Limpopo Province of South Africa. Field studies were conducted at two locations in the province namely, the University of Limpopo experimental farm at Syferkuil, and a farmer’s field at Dalmada during the 2002/2003 growing season, to determine patterns of nodulation in cowpea and lablab varieties under sole culture and in an intercropping system with maize, variety SNK2147 and also to assess biomass accumulation and grain yielding abilities of the component crops in the system. The experiments were established as a randomized complete block design with three replications at each location. Treatments examined were sole maize, two cowpea cultivars: Bechuana white and Glenda; two lablab cultivars, Rongai and Common. The legumes were intercropped alternately within 90 cm inter-row spacing of maize, thus creating a distance of 45 cm between the maize and the legume rows. Cropping system had no effect on cowpea grain yield at Syferkuil, but at Dalmada cowpea yield was reduced. Maize grain yield was significantly affected by the cropping system at both Syferkuil and Dalmada. At both locations, the yields of all the intercropped maize were lower than those of the sole crop maize. The dry matter production of different cropping systems was generally similar during the different sampling dates. / the National Research Foundation,and the Gauteng Department of Agriculture Conservation and Environment