The objective of this study was to evaluate the morpho-agronomic traits of eighty five accessions of elephant grass (Pennisetum purpureum Schum.) from the germplasm bank located at the Experimental Field of the State Center for Research on Bioenergy and Waste Recovery (Centro Estadual de Pesquisa em Agroenergia e Aproveitamento de Resíduos). The experimental design was a randomized block with two replicates, in an annual-harvest system. The evaluated traits were: percentage of dry matter (%DM), dry matter yield (DMY), number of tillers per linear meter (NT), plant height (HGT), stem diameter (SD), leaf blade width (LW) and leaf blade length (LL). Each cut and variable underwent variance analysis and the Scott-Knott test (P<0.05). Tocher’s optimization method, Mahalanobis distance and canonic variables were used for the multi-traits, and importance of the characters in the canonic variables. The following elite genotypes were identified by the Scott-Knott test at 5%: Rico 534-B, Taiwan A-144, Napier S.E.A., Mole de Volta Grande, Teresópolis, Taiwan A-46, Duro de Volta Grande, Turrialba, Taiwan A-146, Cameroon Piracicaba, Taiwan A-121, P241 Piracicaba, Elefante Cachoeira Itapemirim, Guaco/I.Z.2, Cameroon, IJ 7126 cv EMPASC 310, IJ 7139, Australiano, 10 AD IRI, and Pasto Panamá. By the analysis of the canonic variables, the first two accumulated 64.6457% of variance. Regarding the relative importance of the evaluated traits, the leaf blade length at cut two was the most important. By Tocher’s optimization method, the eighty five accessions were divided into twenty five groups, indicating a high variability in the germplasm bank. Key words: Pennisetum purpureum, Tocher’s optimization, Mahalanobis distance, elephant grass.

This study aimed to evaluate cowpea genotypes for adaptability and stability of grain yield using different methods, in order to support the launch and/or cultivars recommendation for agribusiness in the Brazilian Midwest. Trials were conducted from 2010 to 2012 in four locations, totaling eight environments. We evaluated 20 cowpea genotypes arranged in a randomized block design with four replications. Studies of adaptability and stability of cowpea genotypes were estimated using different methods. The environments A1, A5, A6 and A8 are the most appropriate for selecting superior genotypes for adaptability and stability. The genotypes MNC03-737F-5-1 BRS-Tumucumaque, BRS-Guariba, MNC02-684F-5-6, MNC03-725F-3, MNC02-682F-2-6, BRS-Cauamé, BRS-Itaim and MNC03- 737F-5-11 showed adaptability and stability sufficient for recommendation for the region. Eberhart and Russell, Lin and Binns and AMMI methods can be used as a complementary way to better predict the genotype performance. Key words: Genotype, environment interaction, selection Vigna unguiculata.

The aim of this study was to select erect cowpea (Vigna unguiculata L.) genotypes simultaneously for high adaptability, stability, and yield grain in Mato Grosso do Sul, Brazil using mixed models. We conducted six trials of different cowpea genotypes in 2005 and 2006 in Aquidauana, Chapadão do Sul, Dourados, and Primavera do Leste. The experimental design was randomized complete blocks with four replications and 20 genotypes. Genetic parameters were estimated by restricted maximum likelihood/best linear unbiased prediction, and selection was based on the harmonic mean of the relative performance of genetic values method using three strategies: selection based on the predicted breeding value, having considered the performance mean of the genotypes in all environments (no interaction effect); the performance in each environment (with an interaction effect); and the simultaneous selection for grain yield, stability, and adaptability. The MNC99542F-5 and MNC99-537F-4 genotypes could be grown in various environments, as they exhibited high grain yield, adaptability, and stability. The average heritability of the genotypes was moderate to high and the selective accuracy was 82%, indicating an excellent potential for selection.

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.