ABSTRACT The mixed-model methodology is an alternative to select genotypes for traits highly influenced by the environment. In addition, this method allows FOR estimating the repeatability coefficient and predicting the number of assessments needed for a selection process to increase reliability. This study aimed to determine the minimum number of evaluations necessary for a reliable selection process and to estimate the variance components used for predicting genetic gains between and within half-sib families of elephant grass ( Cenchrus purpureus (Schumach.) Morrone ) using the mixed-model methodology. Half-sib families were generated using genotypes from the Active Germplasm Bank of Elephant Grass. The experiment was performed in a randomized block design with nine half-sib families, three replicates, and eight plants per plot. We evaluated 216 genotypes (individual plants) of elephant grass. The deviance analysis was carried out, genetic parameters were estimated, gains between and within families were predicted, and repeatability coefficients were obtained using Selegen software. There was genetic variability for selection within the families evaluated. The reliability values found above 60 % for plant height and number of tillers and above 80 % for dry matter yield suggest that only two evaluations are required to select superior genotypes with outstanding reliability. Sixteen genotypes were identified and selected for their productive potential, which can be used as parents in elephant grass breeding programs for bioenergy production.

Abstract Aim Based on a study comprising water reservoirs within the Brazilian Cerrado biome, we seek to answer the following question: how does phytoplankton communities respond to environmental, landscape, and spatial predictors? We expected local predictors to be the main factors structuring the communities. Since phytoplankton has high dispersal capacity, the geographical distance would be of minor importance. Methods: We collected phytoplankton samples from 40 water reservoirs in the rainy season and 37 reservoirs in the dry season. We performed a partial Redundancy Analysis (pRDA) to evaluate the factors influencing the variation in the composition of phytoplankton communities. Results We found that spatially structured environmental factors were controlling phytoplankton communities at the rainy season, whereas landscape was the main predictor in the dry season. On the other hand, phytoplankton morphofunctional groups were influenced only by local predictors. Conclusions We demonstrated that phytoplankton dynamics differs between rainy and dry seasons, and that distinct predictors affect phytoplankton communities over seasons.

Resumo Objetivo Com base em um estudo envolvendo reservatórios de água no bioma Cerrado brasileiro, buscamos responder a seguinte questão: como a comunidade fitoplanctônica responde a preditores ambientais, uso e ocupação do solo (paisagem) e preditores espaciais? Esperávamos que os preditores locais fossem os principais fatores estruturantes da comunidade. Como os organismos fitoplanctônicos têm grande capacidade de dispersão, a distância geográfica seria de menor importância. Métodos Coletamos amostras de fitoplâncton de 40 reservatórios de água na estação chuvosa e em 37 reservatórios na estação seca. Realizamos uma Análise de Redundância Parcial (pRDA) para avaliar os fatores que influenciam a variação na composição das comunidades fitoplanctônicas. Resultados Na estação chuvosa, encontramos sinais de que fatores ambientais espacialmente estruturados estavam controlando as comunidades fitoplanctônica, enquanto a paisagem foi o principal preditor na estação seca. Por outro lado, os grupos morfofuncionais do fitoplâncton foram influenciados apenas por preditores locais. Conclusões Demonstramos que a dinâmica das comunidades fitoplanctônicas difere na estação chuvosa e seca e que diferentes preditores afetam o fitoplâncton ao longo das estações do ano.

Resumen La canola es una materia prima potencial para la producción de biodiesel debido a sus altos niveles de eficiencia energética. Sin embargo, Brasil aún no ha consolidado su producción pues se desarrolla en las regiones templadas. Este estudio tuvo la hipótesis de que es posible obtener altos rendimientos de canola en condiciones de Cerrado. Así, el objetivo de este estudio fue evaluar el comportamiento agronómico de los híbridos de canola en las condiciones tropicales de la Sierra brasileña - Cerrado - (15 ° 35’18 “S, 47 ° 43’57” W a 999 m) para seleccionar candidatos que contribuyan con la expansión del cultivo de canola en el país. Se evaluaron ocho híbridos comerciales de canola para siete carac terísticas agronómicas, en tres experimentos. Los datos obtenidos para cada variable se sometieron a análisis conjunto de varianza y se compararon las medias mediante la prueba de Tukey. El rendimiento de grano de los híbridos evaluados fue superior al promedio nacional, que incluye plantaciones solo en la región sur. Los híbridos que destacaron en productividad de grano fueron Hyola 61 y Hyola 76 seguidos por Diamond, que además de su alta productividad, tuvo un ciclo de cultivo más corto incluso en condiciones de secano. Por sus características, el híbrido Diamond puede considerarse la mejor opción para ser incluido en el sistema de rotación de cultivos. Estos resultados prometedores revelan la adaptabilidad y el potencial de cultivo de estos híbridos en el Cerrado Brasileño.

Abstract Given its high energetic efficiency, canola (Brassica napus L.) constitutes a potential biodiesel feedstock. However, since this crop is native to temperate regions, Brazil has not yet consolidated its production. Thus, the objective of this study was to evaluate agro nomic performance of canola hybrids grown in the tropical Brazilian Cerrado (15° 35’18” S, 47° 43’57” W at 999 m), aiming to select promising candidates for crop expansion. Our hypothesis states that obtaining high canola yields in Cerrado conditions is possible given a favorable agronomic adaptation of the species to this environment. Eight commercial canola hybrids were evaluated for seven agronomic traits in three experiments. Data were subjected to joint ANOVA and Tukey test. Grain yield of the evaluated hybrids resulted higher than the national average, including southern plantations. Hyola 61 and Hyola 76 hybrids outperformed regarding grain yield, followed by Diamond which, in addition to high productivity, exhibited a short crop cycle, even in rainfed conditions. Given these char acteristics, Diamond hybrid can be considered the best option for crop rotation system. These promising results reveal the adaptability and cultivation potential of these hybrids in the Brazilian Cerrado.

ABSTRACT Jatropha curcas L. is a perennial plant with great potential for biodiesel production. Thus, the aim of this study was to select J. curcas genotypes for bioenergy purpose considering multitrait, multiharvest and effective population size. To this end, a data set with 70 J. curcas families, obtained through controlled crosses, evaluated in a randomized block design, with six replications, three plants per plot, spaced at 4 × 2 m was used. The following traits were evaluated: plant height in the 2014 and 2015 crop seasons; canopy projection in the row (2015 crop season); canopy projection between rows (2015 crop season); and grain yield (2015, 2016, and 2017 harvests). The mixed model methodology was used to estimate the variance components and to predict the genetic values. Superior genotypes were selected through Multitrait index based on factor analysis and genotype-ideotype distance (FAI-BLUP index), considering the effective population size. According to this index, 98% of all additive genetic variability were summarized in three factors. By adopting the selection intensity that allows maintaining the effective population size equal to 30 (i.e., selection of 214 individuals), the predicted gains were 15.56, 21.75, 4.16, and 5.37% for the traits grain yield in the 2015 and 2016 harvests, canopy projection in the row, and canopy projection between rows in the 2015 crop season, respectively. Thus, the results suggest that the FAI-BLUP index can be successfully used in J. curcas breeding.

RESUMO A deficiência hídrica provoca alterações no desenvolvimento vegetal cuja reversibilidade depende do genótipo, da duração do estresse, da severidade do dano causado e do estádio de desenvolvimento em que a planta sofreu estresse. O feijão-caupi é considerado tolerante ao déficit hídrico, no entanto, estudos demonstraram que seu rendimento pode ser reduzido sob essa condição. O objetivo deste trabalho foi avaliar o efeito do déficit hídrico em populações F2 de feijão-caupi e selecionar genótipos tolerantes. Foram conduzidos dois ensaios para a avaliação das 30 populações F2, juntamente com seus genitores (1-BRS Paraguaçu, 2-Pingo de Ouro-1-2, 3-BRS Xiquexique, 4-CNCx 698-128G, 5-Santo Inácio e 6-MNC99-510F-16-1), sendo um sob déficit hídrico, imposto e outro sob irrigação plena. Os experimentos foram conduzidos no campo experimental da Embrapa Meio-Norte, em Teresina, PI. Utilizou-se o delineamento experimental látice triplo. A parcela experimental foi constituída de seis linhas de 2m, com espaçamento de 1,0 m entre linhas e 0,50 m entre plantas. Avaliou-se a produção de grãos e foi calculado o percentual de redução na produção de grãos associado a índices de produção relativa e a tolerância ao estresse. O déficit hídrico, na média, reduziu em 29,83% a produção de grãos dos genótipos. As populações que apresentaram alta produção e alta tolerância ao déficit hídrico foram: BRS Paraguaçu x CNCx 698-128G, BRS Xiquexique x Pingo de Ouro-1-2, CNCx 698-128G x BRS Xiquexique, CNCx 698-128G x MNC99-510F-16-1, Santo Inácio x BRS Xiquexique e MNC99-510F-16-1 x BRS Paraguaçu.

ABSTRACT Water deficit affects plant development and the overcoming of its effects depends on the genotype, duration of stress, severity of damage and development stage of the plant at water stress. Cowpea is considered tolerant to water deficit, however, studies have shown that its yield can be reduced under this condition. Thus, the objective of this work was to evaluate the effect of water deficit on F2 populations of cowpea and select tolerant genotypes. Thirty F2 populations of cowpea and their parents (BRS-Paraguaçu, Pingo-de-Ouro-1-2, BRS-Xiquexique, CNCx-698-128G, Santo-Inácio and MNC99-510F-16-1) were evaluated in two experiments, one under induced water deficit and other under full irrigation, in the experimental field of the Embrapa Mid-North, in Teresina, State of Piauí, Brazil. A triple lattice incomplete block experiment design was used, with three replications. The experimental plots consisted of six 2-m rows, with spacing of 1.0 m between rows and 0.50 m between plants. The grain production was evaluated and its decrease related to the relative production and tolerance to stress was calculated. The grain production of the genotypes had an average decrease of 29.83% under water deficit. The genotypes from the crosses BRS-Paraguaçu x CNCx-698-128G, BRS-Xiquexique x Pingo-de-Ouro-1-2, CNCx-698-128G x BRS-Xiquexique, CNCx-698-128G x MNC99-510F-16-1, Santo-Inácio x BRS-Xiquexique and MNC99-510F-16-1 x BRS-Paraguaçu had high production and high tolerance to water deficit.

RESUMO A baixa adoção de tecnologias pelos agricultores e a ocorrência de estresses bióticos e abióticos são fatores que limitam a produção do feijão-caupi na região Nordeste do Brasil. A tolerância de genótipos à seca é uma das formas para diminuir os efeitos negativos dos estresses sobre a produtividade. O objetivo deste trabalho foi identificar genitores e combinações promissoras com maior probabilidade de gerarem populações segregantes de feijão-caupi tolerantes à seca. Foi realizado um dialelo completo envolvendo seis genótipos de feijão-caupi, totalizando 30 populações F2, que foram avaliadas, juntamente com seus genitores, em um ensaio sob déficit hídrico, no campo experimental da Embrapa Meio-Norte, em Teresina-PI. Utilizou-se o delineamento experimental látice triplo, com parcela de 6 linhas de 2 m, sendo amostradas 15 plantas por parcela. Foram avaliados caracteres agronômicos e submetidos à análise de variância e, utilizando-se das médias, obtiveram-se as estimativas de capacidade geral e específica de combinação. Observou-se diferenças significativas para todos os caracteres, evidenciando a existência de variabilidade genética na população. Os efeitos aditivos foram mais importantes que os efeitos não aditivos, sendo também constatada a presença de herança materna. Os genótipos BRS Xiquexique, Pingo de Ouro-1-2 e MNC99- 510F-16-1 foram os mais promissores para utilização em programa de seleção recorrente visando tolerância ao déficit hídrico. As combinações híbridas (1) BRS Paraguaçu X (4) CNCx 698-128G, (2) Pingo de Ouro-1-2 X (3) BRS Xiquexique, (3) BRS Xiquexique X (5) Santo Inácio, (4) CNCx 698-128G X (6) MNC99-510F-16-1 e (5) Santo Inácio X (4) CNCx 698-128G, possuem potencial simultâneos para extração de linhagens superiores quanto à produtividade de grãos e tolerantes ao déficit hídrico.

ABSTRACT The low use of technologies by farmers and the occurrence of biotic and abiotic stresses are limiting factors for cowpea production in the Brazilian Northeast region. The tolerance of genotypes to drought is an alternative to decrease the negative effects of stresses on cowpea production. Thus, the objective of this work was to identify parents and combinations of cowpea genotypes with high probability of generating segregating populations with tolerance to drought. Six cowpea genotypes were crossed in a complete diallel cross design, totaling 30 F2 populations, which were evaluated together with their parents in an experiment under water deficit at the experimental field of the Embrapa Mid-North, Teresina, State of Piauí, Brazil. A triple lattice incomplete block experiment design was used, with three replications, with experimental plot consisting of six 2-m plant rows. Fifteen plants per plot were sampled to evaluate their agronomic characteristics, whose results were subjected to analysis of variance and means were used to estimate the general and specific combining abilities. The genotypes showed significant differences in all characteristics evaluated, denoting the genetic variability of the population. The additive effects were more important than the non-additive effects, and maternal inheritance was detected. The genotypes BRS Xiquexique, Pingo-de-Ouro-1-2 and MNC99-510F-16-1 were the most promising for use in recurrent selection programs for tolerance to water deficit. The hybrid combinations (1) BRS Paraguaçu X (4) CNCx-698-128G, (2) Pingo-de-Ouro-1-2 X (3) BRS Xiquexique, (3) BRS Xiquexique X (5) Santo-Inácio, (4) CNCx-698-128G X (6) MNC99-510F-16-1 and (5) Santo-Inácio X (4) CNCx-698-128G showed potential for generating superior lineages regarding bean production and tolerance to water deficit.

Abstract The objectives of this study were to estimate the general and specific combining ability of the parents, and to verify the existence of maternal effect and inbreeding depression in Jatropha. The experiment was carried out from 2010 to 2015, in the municipality of Planaltina, Distrito Federal. The following traits were evaluated: plant height, stem diameter, canopy projection between the row, canopy projection on the row, number of branches, mass of one hundred grains, and grain yield. Cytoplasmic effects and effects of female parent nuclear genes were observed for all traits. Dominance effects were predominant in the genetic control of all traits. Genotypes 107 and 190 were the superior parents for the reduction of the size, and for the increase of grain yield. No inbreeding depression was observed for grain yield. The most promising crosses for the conduction of segregating populations and increment in grain yield were 190x107, 107x190 and 259x107.

RESUMO O objetivo desse trabalho foi utilizar diferentes critérios de seleção para identificar genótipos de feijão-caupi tolerantes ao déficit hídrico, a serem utilizados em programas de seleção recorrente, visando redução do ciclo e incremento nos componentes produtivos. Seis genótipos de feijão-caupi foram cruzados no esquema dialélico completo. Foi conduzido um ensaio em delineamento experimental de blocos incompletos em arranjo do tipo látice triplo para avaliar as 30 populações F2 de feijão-caupi. Após verificar variabilidade genética para 10 caracteres, empregaram-se os seguintes critérios de seleção: seleção direta e indireta, índice clássico, índice baseado nos ganhos desejados e índice baseado em soma de ranks. Os caracteres número de dias para o início de floração (NDIF), número de dias para a maturidade (NDMD), peso da vagem (PV), peso de grãos por vagem (PGV), peso de 100 grãos (PCG) foram considerados como primários, e os demais como secundários. A seleção direta com base no caráter peso de vagem é o critério mais eficiente para reduzir o ciclo e incrementar os componentes produtivos em genótipos de feijão-caupi submetidos ao déficit hídrico. Os genótipos Pingo de Ouro-1-2 x MNC99-510F-16-1, CNCx 698-128G x MNC99-510F-16-1, MNC99-510F-16-1 x Pingo de Ouro-1-2, Pingo de Ouro-1-2 x BRS Paraguaçu, Santo Inácio x Pingo de Ouro-1-2, BRS Xiquexique x Pingo de Ouro-1-2 e Pingo de Ouro-1-2 x Santo Inácio são os mais indicados para serem utilizados em programas de seleção recorrente interpopulacional, visando redução do ciclo e aumento nos componentes produtivos do feijão-caupi, quando submetido ao déficit hídrico.

ABSTRACT The objective of this work was to use different selection criteria to identify cowpea genotypes tolerant to water deficit to be used in recurrent selection programs aiming to reduce the cowpea crop cycle and improve its productive components. Six cowpea genotypes were crossed in a complete diallel scheme. The experiment was conducted in an incomplete block experimental design in a triple lattice arrangement, with the 30 F2 populations of cowpea. The genetic variability of 10 traits was verified, and the following selection criteria were used: direct and indirect selection, classical index, index based on desired gains, and index based on sum of ranks. The number of days to flowering (NDF), number of days to maturity (NDMD), pod weight (PW), grain weight per pod (GWP) and 100-grain weight (100GW) were classified as primary traits, and the others as secondary. The direct selection based on the pod weight was the most efficient criterion to reduce the crop cycle and improve productive components of the cowpea genotypes subjected to water deficit conditions. The genotypes Pingo-de-Ouro-1-2 × MNC99-510F-16-1, CNCx698-128G × MNC99-510F-16-1, MNC99-510F-16-1 × Pingo-de-Ouro-1-2, Pingo-de-Ouro-1-2 × BRS Paraguaçu, Santo-Inácio × Pingo-de-Ouro-1-2, BRS Xiquexique × Pingo-de-Ouro-1-2 and Pingo-de-Ouro-1-2 × Santo-Inácio were the most suitable to be used in interpopulation recurrent selection programs aiming to reduce the crop cycle and improve productive components of cowpea grown under water deficit conditions.