A mamona é uma cultura importante no nordeste brasileiro há muito tempo e é característica de pequenos produtores que utilizam mão de obra familiar. Devido a isso, a maioria deles não utiliza ainda cultivares melhorados e até o momento poucos cultivares de mamona foram liberados pelos programas de melhoramento. Nos últimos anos a cultura da mamona tornou-se importante também em outras regiões do Brasil, devido à importância que adquiriu o óleo extraído das suas sementes para a produção de biodiesel. O objetivo deste trabalho compreende a estimação de parâmetros genéticos e fenotípicos relacionados à produção e caracteres agronômicos de mamona, visando ao entendimento do controle genético de tais caracteres para fins de melhoramento. Para isso utilizou-se 10 genótipos de mamona, divididos em dois grupos: Grupo 1, composto de cinco genótipos de porte baixo, e, Grupo 2, composto de cinco genótipos de porte alto, que foram cruzados segundo um arranjo dialélico parcial, originando 25 cruzamentos. Os 25 tratamentos foram avaliados experimentalmente no ano agrícola de 2005/6 na área experimental do Departamento de Genética da ESALQ/USP, em um delineamento em látice 5 x 5 com quatro repetições e parcelas lineares de 9 metros, espaçadas de 3 metros, contendo 10 plantas. Os seguintes caracteres foram avaliados: produção de sementes (PR), peso de 100 sementes (P100), dias para florescimento (DF), altura da planta (AP), altura do caule (AC), diâmetro do caule (DC), comprimento total do racemo primário (TT), comprimento efetivo do racemo primário (TU), número de nós (NN) e comprimento dos internós (CI). A capacidade geral de combinação (CGC) foi significativa para todos os caracteres dos dois grupos na análise de variância, enquanto que a capacidade específica de combinação (CEC) foi significativa somente para P100, DF, DC, TT, TU e NN. Mesmo assim, a soma de quadrados devido à CGC foi maior que a soma de quadrados devido à CEC em todos estes caracteres. Nos dois grupos detectaram-se genótipos com alelos favoráveis para produção de sementes e caracteres agronômicos. Dois genótipos do Grupo 1 (BRA-5916 e BRA-3908) e dois do Grupo 2 (BRS Paraguaçu e BRS Nordestina) se destacaram pela maior concentração de alelos favoráveis para PR e características agronômicas, havendo complementação entre eles. Com base nestes resultados sugere-se a formação de populações derivadas de cruzamentos duplos, triplos e quádruplos com estes genótipos, visando à seleção de linhagens de alta produção e com características agronômicas favoráveis. / Castor has been a very important crop in northeastern Brazil, and has been characterized as low input agriculture of small farmers. Nowadays it became a very important crop in other places of Brazil, due to the possibility of biodiesel production. Most of castor crop in Brazil is based in landraces and only a few cultivars were released by breeding programs. The objective of the present work was to estimate the genetic and phenotypic parameters related to seed yield and agronomic traits in castor, in order to obtain a better understanding of the genetic control of these traits for breeding purposes. The genetic material comprised two sets of cultivars: Group 1, composed by five short genotypes, and Group 2, composed by five tall genotypes. The two groups were crossed according a partial diallel design, giving rise to 25 hybrid combinations. The 25 entries were evaluated under field conditions in the 2005/6 growing season, at Department of Genetics Experimental Station, College of Agriculture Luiz de Queiroz (ESALQ/USP) in a 5 x 5 lattice design with four replicates. Plots consisted of a 9-meter single row spaced 3 meter apart with 10 plants. The following traits were evaluated: seed yield (PR), 100-seed weight (P100), days to flowering (DF), plant height (AP), height up to primary raceme (AC), diameter of main stem (DC), total length of primary raceme (TT), effective length of primary raceme (TU), number of nodes up to primary raceme (NN) and length of internodes below the primary raceme (CI). General combining ability (GCA) was significant in the analysis of variance for all the traits in the two groups, while specific combining ability (SCA) was significant only for P100, DF, DC, TT, TU and NN. However, GCA sum of squares was higher than SCA sum of squares for all these traits. Both groups showed the presence of genotypes with favorable alleles for yield and agronomic traits. Two genotypes from Group 1 (BRA-5916 and BRA-3908) and two from Group 2 (BRS Paraguaçu and BRS Nordestina) presented a higher concentration of favorable alleles for PR and agronomic traits and were also complementary. We suggest the development of two-way, three-way and four-way populations with these genotypes, in order to select high yielding inbred lines and with other favorable traits.

Grandes esforços dos programas de melhoramento genético da cana-de-açúcar são dedicados ao desenvolvimento de novas variedades com maior rendimento e conteúdo de sacarose. As etapas do metabolismo da sacarose têm sido foco de pesquisas há muito tempo, porém apenas recentemente têm-se buscado compreender os processos de transporte e acúmulo da sacarose no colmo da cana-de-açúcar. O objetivo deste trabalho é a caracterização do proteoma de entrenós maduros (entrenó 9) e imaturos (entrenó 5) de dois genótipos de cana-de-açúcar (Co 740 e SP 80-3280), ambos com 12 meses de idade, visando à identificação de proteínas relacionadas aos processos de transporte e acúmulo de sacarose. A altura, diâmetro do colmo, área foliar, umidade dos entrenós, trocas gasosas, potencial hídrico da planta e índice de maturação foram obtidos no momento da coleta do material vegetal. A quantificação dos açúcares glicose, frutose e sacarose foi realizada por cromatografia líquida e não mostrou a existência de diferenças no acúmulo desses carboidratos entre as duas variedades. Porém observamos diferenças entre os entrenós maduros e imaturos, indicando que o entrenó considerado imaturo encontra-se em estádio de pleno acúmulo de sacarose. O perfil de expressão proteica, gerado por 2D-PAGE, mostrou 87 e 85 proteínas diferencialmente expressas nos entrenós 5 e 9, respectivamente. Nos entrenós imaturos 12 proteínas foram identificadas como preferencialmente expressas em cada variedade e nos entrenós maduros 11 e 16 proteínas foram identificadas como preferencialmente expressas em Co 740 e SP 80-3280, respectivamente. As proteínas totais dos dois entrenós das duas variedades foram separadas e identificadas via UPLC acoplado a espectrômetro de massas LC-MS/MS com auxílio da base de dados do SUCEST. A caracterização do proteoma dos entrenós foi complementada pela avaliação da localização celular, função molecular e processo biológico a que pertencem todas as proteínas identificadas. Ao todo, foram identificadas 1.493 proteínas localizadas em 19 componentes celulares, com 20 funções metabólicas diferentes, atuantes em 24 processos biológicos e integrantes de 84 vias metabólicas. Deste total, 71 foram classificadas como participantes do metabolismo de carboidratos e encontram-se distribuídas em 21 vias metabólicas, segundo a base de dados KEGG. / Great efforts have been put into sugarcane breeding programs in order to develop new varieties with increased sucrose yield and content. The steps of sucrose metabolism have been focus of research for a long time, but only recently have researchers sought to understand the processes of transport and accumulation of sucrose in sugarcane stem. The objective of this study is characterize the proteome of mature (internode 9) and immature (internode 5) internodes in two genotypes of sugarcane (Co 740 and SP 80-3280), both 12 months old, focusing on the identification of proteins related to the processes of transport and accumulation of sucrose. The height, stem diameter, leaf area, internode moisture, gas exchange, plant water potential and maturation index were all recorded at the time the plant material was collected. The quantification of sugars glucose, fructose and sucrose was performed by liquid chromatography and showed no difference in carbohydrates accumulation between the two varieties. Nevertheless, we observed differences between the mature and immature internodes, indicating that the internode considered immature was actively accumulating sucrose. The protein profile, produced by 2D-PAGE, showed 87 and 85 differentially expressed proteins in internodes 5 and 9, respectively. In immature internodes 12 proteins were identified as being preferentially expressed in each of the varieties and in the mature internodes 11 and 16 proteins were identified as preferentially expressed in Co 740 and SP 80- 3280, respectively. Total proteins of the two internodes of two varieties were separated and identified by UPLC coupled to a mass spectrometer LC-MS/MS using the SUCEST database. The characterization of the internodes proteome was further complemented by evaluating cellular localization, function and molecular biological processes to which all identified proteins belong. Altogether, 1,493 proteins were identified, located in 19 cellular components, with 20 different metabolic functions, operating in 24 biological processes and involving 84 metabolic pathways. Of this total, 71 have been classified as being involved in carbohydrate metabolism and are distributed in 21 metabolic pathways, according to the KEGG database.

Este estudo foi realizado com base nos resultados experimentais relativos a genótipos RB da Série 92 do Programa de Melhoramento Genético da Cana-de-Açúcar da Universidade Federal de São Carlos (PMGCA UFSCar), tendo como finalidade avaliar a representatividade dos locais que compõe sua rede experimental. Para isso foram avaliados os caracteres Toneladas de colmo por hectare (TCH), Pol % da cana (PC) e Toneladas de Pol por hectare (TPH) de 15 genótipos em 13 locais, sendo estes locais referentes às Usinas : Santa Fé, Santa Luiza, Santa Terezinha, São Martinho, Cocal, Bonfim, Santa Elisa - 1, Cruz Alta, Iturama, Aralco, Lucélia, Sonora e Santa Elisa - 2. A partir das análises de variância individuais e conjuntas, foram realizados testes de agrupamento baseado na metodologia de Lin, que se baseia no quadrado da distancia euclidiana para agrupar locais que apresentem similaridade nas respostas dos genótipos; entretanto, com dois critérios de significâncias para a interação genótipos x locais, tais como: p 0,05 (original) e p 0,30 (modificada), para os três caracteres avaliados. A metodologia de Lin original (p 0,05) mostrou ser pouco confiável, podendo possibilitar o agrupamento de locais com valores de quadrados médios da interação genótipos x locais muito próximos da significância. Já a metodologia de Lin modificada mostrou ser mais confiável, apresentando, portanto, menos possibilidades de agrupamento. Assim, por meio da metodologia de Lin (1982) modificada, pode-se notar que se forem considerados os três caracteres simultaneamente (TCH, PC e TPH), apenas os locais referentes às Usinas Santa fé e Cruz Alta poderiam se juntar para formar um grupo, o que possibilitaria a redução de 13 locais para 12 locais. Isso mostra que os locais de experimentação da UFSCar são bem representativos das regiões estudadas. / This study was performed on the basis of experimental results concerning RB genotypes belonging to Series 92 of the sugarcane breeding program of the Universidade Federal de São Carlos (PMGCA - UFSCar), having as purpose to evaluate representativeness of the locations that compose its experimental net. This way, the characters tons of cane per hectare (TCH), Pol % sugar (PC) and Tons of Pol per hectare (TPH) of 15 RB genotypes cultivated in 13 locations, were evaluated. These locations belongs to the following Sugar factories: Santa Fé, Santa Luíza, Santa Terezinha, São Martinho, Cocal, Bonfim, Santa Elisa - 1, Cruz Alta, Iturama, Aralco, Lucélia, Sonora and Santa Elisa - 2. From the individual and joint analyses of variance, tests of grouping based on the methodology of Lin which is based on the Square of Euclidean distance for grouping locations that present similarity in behavior of the genotypes were carried out; however, with two significance criteria of the genotypes by locations interaction, such as: p 0,05 (original) and p 0,30 (modified), for those three parameters evaluated. The original Lin (p0,05) methodology was shown not to be very precise allowing grouping locations that presented average mean squares values of the interaction genotypes by locations very close to the significance. On the other hand, the modified Lin methodology (p 0,30) showed to be more precise, presenting, therefore, less possibilities of grouping. Thus, by using the modified Lin methodology (1982), it can be noticed that if the three characters (TCH, PC and TPH) are simultaneously considered , only the locations related to Santa Fé and Cruz Alta Sugar factories could be joined to form a group, and that would make possible the reduction from 13 to 12 experimental locations. This result show that the locations of experimentation of the UFSCar breeding program are well representative of the studied regions.

Master of Science / Department of Agronomy / Ignacio Ciampitti / Soybean [Glycine max (L.) Merr.] yields have continuously increased over time. Seed yields are determined by the genotype, environment, and management practices (G × E × M) interaction. Closing yield gaps require a continuous improvement in the use of the available resources, which must be attained via implementation of better management decisions. Linear relationships between seed yield and nitrogen (N) demand are reported in the scientific literature. Main sources of N to the plant are the biological N fixation (BNF) and the soil mineralization processes. On overall, only 50-60% of soybean N demand is met by the BNF process. An unanswered scientific knowledge is still related to the ability of the BNF to satisfy soybean N demand at varying yield levels. Seed N demand not met by N fixation plus soil mineral N, is then fulfilled by the remobilization of N from vegetative organs during the seed filling period. An early remobilization process reduces the photosynthetic activity (leaves) and can limit seed yield. The objectives of this project were to: i) study yield improvements and contribution of N via utilization of contrasting N conditions under historical and modern soybean genotypes, and ii) quantify main seed N sources during the seed filling period. For objective one, four field experiments were conducted during the 2016 and 2017 growing seasons in Kansas, United States (US) and Santa Fe Province, Argentina (ARG). Those experiments investigated twenty-one historical and modern soybean genotypes with release decades from 1980s to 2010s. As for objective two, three field experiments were conducted during the 2015 and 2016 growing seasons in Kansas, US, studying three soybean genotypes: non-roundup ready (RR), released in 1997; RR-1, released in 2009; and RR-2, released in 2014. Across all studies, seeds were inoculated and tested under three N management strategies: i) control without N application (Zero-N); ii) 56 kg N ha-1 applied at reproductive growth stages (Late-N); and iii) 670 kg ha-1 equally split at three timings (Full-N). As for yield improvements and N limitation, soybean yield improvements from the 1980s to 2010s were documented, representing 29% increases in the US and 21% in ARG. Regarding N management, the Full-N fertilization produced a 12% increase in seed yields in the US and 4% in ARG. As for main seed N sources in objective two, remobilization accounted for 59% of seed N demand, and was negatively related to new N uptake occurring during the seed filling period. Seed N demand for greater yields was dependent on both, N remobilization and new N uptake, while for lower yields, seed N demand was mainly supported by the N remobilization process. These results suggest that: a) high seed yields are somehow limited by the availability of N to express their potential, although the question about N application still remains to be fully investigated, as related to the timing and the environment by plant interactions that could promote a N limitation in soybeans; b) remobilization accounts for majority (59%) of N sourced to the seed, and c) high yielding soybean (modern genotypes) rely on diverse N sources: the N remobilization process plus new uptake of N.

Embora os morcegos sejam hospedeiros de tripanossomas de vários subgêneros, o conhecimento sobre a diversidade genética, variedade de hospedeiros, vetores, ciclos de vida, distribuição geográfica e relações filogenéticas desses tripanossomas é muito limitado. Neste estudo, caracterizamos tripanossomas de morcegos do Brasil e de Moçambique (África). A diversidade morfológica, biológica e genética e o relacionamento filogenético de espécies de Schizotrypanum revelaram os clados T. dionisii e T. c. marinkellei (restritos a morcegos) e T. cruzi. Nossos resultados permitiram descrever um novo genótipo de T. cruzi e uma nova espécie desse subgênero em morcegos africanos. Confirmamos, com análises filogenéticas, a presença de T. rangeli em morcegos e caracterizamos uma nova espécie, tradicionalmente classificada como Megatrypanum, mas filogeneticamente não posicionada neste subgênero. Novas análises, visando melhor resolver as filogenias e estimar tempos de divergências, são necessárias para inferir a hipótese mais provável para a história evolutiva desses tripanossomas. / Although bats are hosts of trypanosomes from several subgenera, our knowledge regarding their genetic diversity, host-range, vectors, life-cycles, geographical distribution and phylogenetic relationships is very limited. Here, we characterized bat trypanosomes from Brazil and Mozambique (Africa). Morphological, biological and genetic diversity, and phylogenetic relationships of Schizotrypanum species disclosed T. dionisii, T. c. marinkellei (bat restricted) and T. cruzi clades. Our findings also enabled the description of a new genotype of T. cruzi and a new species of this subgenus infecting African bats. We also reported T. rangeli in bats confirmed by phylogenetic analysis and characterized a new species of bat trypanosome traditionally classified as Megatrypanum, but not phylogenetically supported in this subgenus. Further analyses aiming better-resolved phylogenies and reliable molecular-clock model to estimate divergence times are required to infer the most likely hypothesis for the evolutionary history of bat trypanosomes.

Trypanosamas de diversas espécies podem infectar mamíferos de interesse econômico em todo o mundo. Trypanosoma vivax, T. evansi, T. equiperdum, T. congolense, T. b. brucei e T. simiae geram importantes doenças em ungulados na África, Ásia e Américas Central e do Sul; enquanto T. theileri e espécies relacionadas são pouco patogênicas. Compreender a epidemiologia e as interações parasita-vector-hospedeiro requer estudos de estrutura populacional, filogeográficos e de diversidade e relações filogenéticas entre isolados. Sequências de microssatelites e dos genes SSUrRNA, gGAPDH, CatL, ITS, SL, 5S, Cytb e ESAG6 mostraram ampla diversidade biológica e diferenciaram genótipos com associação geográfica e restrição de hospedeiros em T. theileri e espécies relacionadas. T. evansi mostrou importante heterogeneidade de sequências no gene ESAG6, enquanto populações de T. vivax muito divergentes foram observadas em regiões preservadas e com transmissão cíclica quando comparadas com a microheterogeneidade biológica de áreas de transmissão mecânica. / Trypanosames can infect diverse species of mammals of economic interest worldwide. Trypanosoma vivax, T. evansi, T. equiperdum, T. congolense, T. brucei brucei and T. simiae cause important diseases in ungulates in Africa, Asia and Central and South America, while T. theileri and related species are of low pathogenicity. Understanding the epidemiology and host-parasite-vector interactions requires studies of population structure, phylogeography and diversity and phylogenetic relationships among isolates. Microsatellite loci and sequences from genes SSUrRNA, gGAPDH, CatL, ITS, SL, 5S, Cytb and ESAG6 revealed high biological diversity and allowed differentiation of genotypes with geographic structure and host-restriction event in T. theileri and related species. T. evansi showed significant heterogeneity in ESAG6 sequences, while populations of T. vivax widely divergent were observed in pristine regions and cyclical transmission compared to the microheterogeneity showed by isolates from mechanical transmission areas.

A proteína de ligação em Duffy (PvDBP) dos merozoítos de P. vivax se liga a glicoproteínas de membrana, chamadas de grupo sanguíneo Duffy, conhecidas como DARC. Indivíduos DARC negativos são normalmente resistentes a infecção estágio sanguínea por P. vivax; portanto, PvDBP é um forte antígeno canditato a vacina. Aqui, investigamos respostas de anticorpos contra três proteínas derivadas de PvDBP e MSP119, em 343 indivíduos de uma região Amazônica brasileira. Anticorpos contra Sal III-His, OII-His, Sal III-IV-GST e MSP119-GST foram encontrados em 43,7%, 39,0%, 14,3% e 38,8% dos indivíduos. Os indivíduos FY*BESFY*BES foram os que menos apresentaram anticorpos contra PvDBP, porém encontramos proporções similares de respondedores entre indivíduos com outros genótipos. A análise de sequências revelou muitas variantes da região II de PvDBP em 41 isolados. A mais comum (encontrada em 28,8% dos isolados), difere de Sal I e PNG- O em seis codóns de aminoácidos. Nenhuma variante tipo Sal I, cujo protótipo de vacina está em teste clínico, foi encontrada nos parasitas locais. / The Duffy binding protein (PvDBP) of the P. vivax merozoites, which binds to a erythrocyte membrane glycoprotein known as Duffy blood group antigen for chemokines (DARC). DARC-negative individuals are usually resistant to blood-stage infection with P. vivax; therefore, PvDBP is a major vaccine candidate antigen. Here, we investigated antibody responses to three proteins derived from PvDBP and MSP119, in 343 subjects in the Amazon of Brazil. Antibodies to Sal III-His, OII-His, Sal III-IV-GST and MSP119-GST were found in 43,7 %, 39,0%, 14,3% and 38,8% of the subjects. FY*BESFY*BES individuals were less likely to have antibodies to PvDBP, but we found similar proportions of seropositive subjects with other genotypes. Sequence analysis revealed several region II PvDBP variants in 41 local P. vivax isolates. The most common of them (found in 28,8% isolates) differs from Sal I and PNG-O alleles in six amino acid codons. No Sal I-type variant, from which a PvDBP-based vaccine prototype currently under clinical testing has been derived, was found in local parasites.

MSCAGR (Plant Production) / Department of Plant Production / Chickpea (Cicer arietinum L) is adapted to cool-seasons and its organs are of high nutritive value and serve as cheap sources of protein, especially in developing countries. Chickpea crop is mainly grown for human consumption, animal feed and for medicinal purposes. The introduction and promotion of chickpea to especially small-scale South African crop farmers has multiple objectives including the improvement of soil fertility. Small-scale farmer’s flounder to afford Nfertilizers, coupled with the challenges faced by programmes aimed at assisting them about soil fertility in their cropping fields that are still without enough N concentration to meet N demand. It is therefore important that other alternatives that can help improve the N status of soils be explored. The shoot δ13C is an indicator of WUE in C3 plants. However, shoot-WUE is affected by a variety of factors including genotypes, phosphorus fertilizer application and availability of native or introduced rhizobial bacteria. However, not much is known on whether application of phosphate fertilizer, seed inoculation with rhizobial strain affect the shoot C/N ratio of chickpea genotypes in South Africa. Therefore, field experiments were established at Thohoyandou and Syferkuil in Limpopo to assess the role of phosphorus fertilization and rhizobial inoculation on C assimilation, C/N ratio and shoot-WUE of chickpea genotypes. Field experiments were conducted during winter season in 2016 and 2017 (April to August). Treatments consisted of a factorial combination of two rates of phosphorus fertilizer (0 and 90 kg P ha-1 ), four desi chickpea genotypes (ACC#1, ACC#2, ACC#3 and ACC#5) and two rhizobial inoculation levels (bradyrhizobium strain and without rhizobial strain. In Thohoyandou, ACC#1 showed greater grain yield in 2016 and 2017. Which was associated with more branches and greater plant height. Furthermore, the interaction between genotypes, phosphorus fertilizer and rhizobial inoculation had significant effect on grain yield in 2016. ACC#1, 3 and 5 of chickpea genotypes fixed the most N compared to that of ACC#2. In addition, ACC#5 had the highest soil N-uptake in both seasons followed by ACC#3, while ACC#1 had the least value of soil N-uptake in both seasons. Phosphorus fertilizer application increased the fixation of N by 36.8% (P≤0.01), and similarly in soil N-uptake by difference of 59.9% compared to control in 2016. Furthermore, rhizobial inoculation increased N-fixed in 2016 and soil N-uptake in both seasons. ACC#5 had the highest N fixed at phosphorus-fertilized with bradyrhizobuim across two locations in both seasons. ACC#5 depended more on soil N-uptake than fixing its own N as compared to ACC#1. N fixation differed across seasons; however, ACC#3 had greater N-fixed in both locations. Moreover, chickpea genotype that fixed more N had least δ15N. This finding indicates that N fixation is exhibited by the genotypes that depend less on δ15N, because N2 fixation is inhibited by high soil N concentration or δ15N. Furthermore, ACC#2 and ACC#3 had greater δ13C at Thohoyandou in 2017; chickpea genotypes had significant effect on δ13C at P≤0.05 at Thohoyandou, 2016. The results showed that ACC#1 with phosphorus fertilizer application and no bradyrhizobium strain showed greater δ13C. Also, δ13C increased with a decrease in N-fixed (r=.1000), this indicates that there was a functional relationship between plant WUE and N fixation in chickpea, probably because improved water use in legumes supports N fixation. / NRF

Thesis (M. Sc.(Agronomy)) -- University of Limpopo, 2015 / Cowpea (Vigna unguiculata L. Walp) is an important grain legume grown in many parts of the world mostly by smallholder (SH) farmers. Low soil phosphorus (P) and drought stress are major constraints to legume production and threaten food security. Root architecture is a spatial configuration of the root system which is influenced by moisture status and P uptake. A field experiment was conducted at Ukulima farm near Modimolle in Waterberg district during 2012/13 summer growing season. The treatments comprised of two levels each for soil P (low and high) and moisture status (water stress and well-watered); and eight cowpea genotypes (Tvu 4632, Tvu 6365, Tvu 9848, Tvu 15445, Tvu 16408, Tvu 15143, Oloyin and IT00K-1217). The low P level implied the available P in the soil measured in situ, which was less than 8 mg kg-1 while the high P level entailed fertilization at the rate of 40 kg P ha-1 application to achieve approximately 35 mg P kg-1 of soil . The root traits measured included angle of adventitious and basal roots, number of basal roots, tap root diameters at 5, 10, 15 and 20 cm soil depths; lateral branching densities at depth 5,10 and 15 cm, nodule score, deep score, shallowness score, 3rd order branching density, and 1.5 branching densities at 5 and 10 cm depth. Plant parameters measured were plant height, number of pods per plant, number of seeds per pod, length of the pods, unshelled weight, shelled weight and number of primary and secondary branches. Photosynthetic parameters measured were photosynthetic rate, intercellular CO2 concentration, water conductance, transpiration rate, vapour pressure deficits, sample cell CO2, sample cell H2O and relative humidity in the cell. All treatment factors were combined as split-split plot arrangement fitted into randomized complete block design; with four replicates. Results indicate that the lateral root branching density at 5 and 10 cm differed significantly (P≤0.05) across cowpea genotypes. Genotype showed significant effect on taproot diameter at 10 cm. Moisture status and P level exerted significant effect on cowpea genotypes 15 cm. There were significant differences (P≤0.05) for lateral root branching density observed at 5 and 10 cm depth in P rates x genotype interaction. Statistical analysis showed that P levels and cowpea genotypes had significant effects (P≤0.05) on mean plant height, biomass and highly significantly effects (P≤0.01) on number of branches, days to physiological maturity and mean pod length. The interaction between cowpea genotype and moisture stress condition significantly (P≤0.05) affected hundred (100) seed weight. Cowpea genotype Tvu16408 obtained highest grain yield of 3240 kg ha-1 and lowest was by IT00K1217 which obtained grain yield of 1256 kg ha-1. Results showed that photosynthetic rate, water conductance, transpiration rate, sample cell CO2, sample cell H2O, relative humidity in the cell, intercellular CO2 and vapour pressure deficit differed significantly (P≤0.05) across cowpea genotypes. Soil moisture condition and cowpea genotype exerted significant (P≤0.01) effect on photosynthetic rate, water conductance, transpiration rate, sample cell CO2, sample cell H2O and relative humidity in the cell. Variation in P levels had no significant effect on the measured photosynthetic parameters. Oloyin genotype had the highest photosynthetic rate followed by Tvu 4632 while cowpea genotype Tvu 9848 had the least photosynthetic rate. Interaction of moisture stress and cowpea genotype had a significant effect on intercellular CO2 concentration. Water stress reduced the intercellular CO2 concentration of Oloyin, Tvu 6365 and 4632 but resulted in a significant increase in intercellular CO2 concentration in Tvu 9848 genotype. Results showed that variation in soil P level exerted a significant (P≤0.05) effect on grain tissue P content and uptake, and a highly significant (P≤0.01) difference in P content across the various cowpea genotypes. Moisture stress exerted a significant (P≤0.05) difference on P uptake. The results showed that P levels and cowpea genotype variation exerted significant (P≤0.05) effects on P content, P uptake and nitrogen (N) uptake. Moisture status and cowpea genotype variation exerted significant (P≤0.05) effects on total N and N uptake. Cowpea genotype Tvu 9848 obtained more total N content (4.37%), while the lowest total N content was obtained by cowpea genotype Tvu 15445 with 3035 mg kg-1. The interaction between cowpea genotype and moisture status exerted a significant (P≤0.05) effect on N and P uptake of immature green pods harvested. There is a need to conduct more studies to identify cowpea genotypes, their root architecture and agronomic measures that can do well under xvii drought stress and low soil P conditions. Research needs to be conducted to enhance cowpea productivity under both low soil P and drought stress. Keywords: cowpea genotypes; moisture stress; phosphorus fertilisation; root traits

Orientador: Ciniro Costa / Banca: Silvio José Bicudo / Banca: Armando de Andrade Rodrigues / Abstract: The aim of this work was to evaluate the agronomical, chemical composition and removal of potassium of five different genotypes of corn grown for silage. A split-plot complete randomized block design was used, with three hybrids (DKB 390, AGX 8517, A-2560) and two varieties (AL-Bianco, Piratininga), using two cut heights (20 and 40 cm above soil level) and four replicates per treatment. After harvest, plants were analyzed for chemical characteristics and potassium (K). Milk production and DM intake were predicted for each treatment. There was an increase in DM content with the increase in cut height (P<0.05): 31.7 e 33.9%, for 20 and 40 cm, respectively. Depending on genotype, estimates of DM yield (ton/ha) ranged from 10.24 to 12.08 for plants cut at 20 cm and from 8.92 to 10.51 for plants cut at 40 cm. On average, there was a decrease (19.1%) in potassium removal by the crop as a result of increased cut height. Increased cut height also led to a decrease in predicted milk production and an increase in predicted DMI. These results suggest that the corn genotypes under study should be harvested at the lower cut height to promote increased animal productivity per ha. / Resumo: O presente experimento teve como objetivo avaliar as características agronômicas, composição químico-bromatológica e extração de potássio de cinco genótipos de milho para silagem. O delineamento foi realizado em parcelas subdivididas no delineamento em blocos ao acaso, com 3 híbridos (DKB 390, AGX 8517, A-2560) e 2 variedades (AL-Bianco, Piratininga), em 2 alturas de corte (20 e 40 cm acima do solo) e 4 repetições. Após a colheita foram realizadas as determinações de parâmetros bromatológicos e potássio (K), bem como simulação para estimativa de produção de leite/ha (EPL) e da ingestão de MS (EIMS). Houve aumento no teor de MS com a elevação da altura de corte (P<0,05), sendo observados valores de 31,7 e 33,9%, para 20 cm e 40 cm respectivamente. A produção de MS/ha para os genótipos cortados a 20 cm variou entre 10,24 e 12,08 t e para 40 cm entre 8,92 e 10,51 t. A elevação na altura de corte reduziu em média 19,1% a extração de potássio. O aumento na altura de corte levou à redução na EPL/ha e ao aumento na EIMS. Os genótipos de milho estudados devem ser cortados a 20 cm de altura do solo por proporcionar maior produtividade animal por área em relação aos genótipos cortados a 40 cm do solo. / Mestre