ABSTRACT. The aim of this study was to evaluate the phenotypic variation and diversity of cassava for breeding purposes based on the pasting properties of starch, for food applications. The viscosities of the starches, extracted from 1031 accessions, were obtained using a Rapid Visco Analyzer. The best linear unbiased predictors were calculated for five critical points of the viscograms, which were then used to cluster the accessions based on the discriminant analysis of principal components. The wide phenotypic variation identified from the viscograms reveals the high potential for selection gains, especially for pasting temperature and setback. Certain strong correlations indicate that selection based on a specific viscogram trait can be used for indirect selection (e.g., the correlation between peak viscosity and breakdown [0.85]). The lowest Bayesian information criterion identified five different groups. Groups 3 and 4 exhibited high pasting temperatures, while Groups 3 and 5 exhibited low setbacks. Group 3 also exhibited low viscosity and breakdown. However, we focused on selecting cassava accessions with a high pasting temperature and low setback, as these are the most important traits for industrial applications. The predicted genetic gains from the selection of the top 15 cassava accessions for increasing pasting temperature and decreasing setback were 4.40% and 53.17%, respectively. The increased pasting temperature (~72.89°C) and high amplitude of setback (~600 cP) due to selection can guide the utilization of the cassava germplasm for breeding and provide a basis for further studies to develop varieties with added value, especially in the food industry.

Resumo: O objetivo deste trabalho foi examinar a possibilidade de usar componentes de produção e caracteres reprodutivos, fisiológicos e de raiz na seleção precoce para eficiência de uso de nitrogênio (EUN) em milho. Foram avaliadas 64 linhagens em dois regimes de adubação nitrogenada: ideal e baixo. As avaliações foram feitas em três estádios fenológicos: oito folhas completamente expandidas, florescimento masculino e maturação fisiológica. É possível selecionar linhagens superiores quanto à EUN, mas os componentes de produção não tiveram comportamento diferencial sob os diferentes níveis de nitrogênio avaliados. Os caracteres radiculares, reprodutivos e fisiológicos não se mostraram confiáveis para seleção precoce de linhagens de milho com elevada EUN. De forma semelhante, os estádios de oito folhas e de florescimento masculino não se mostraram promissores para esse propósito, uma vez que, para a estimação da EUN, deve-se levar em consideração a produção de grãos. Entretanto, a seleção indireta para EUN pode ser feita via número de espigas ou com o uso de índice de seleção que considere número e peso de espigas.

Abstract: The objective of this work was to examine the possibility of using yield components and reproductive, physiological, and root traits in early selection for nitrogen use efficiency (NUE) in corn. Sixty-four inbred lines were evaluated under two nitrogen fertilization levels: ideal and low. The evaluations were performed at three phenological stages: eight fully-expanded leaves, tasseling stage, and physiological maturity. It is possible to select superior lines for NUE, but the yield components did not show differential behavior under the different nitrogen levels evaluated. Root, reproductive, and physiological traits are not promising for early selection of corn lines with high NUE. Likewise, the eight-leaves and tasseling stages were not promising for this purpose, since NUE should be estimated taking grain yield into account. However, indirect selection for NUE can be performed via number of ears or using the selection index considering number and weight of ears.

RESUMO O método GGE Biplot é eficiente em identificar genótipos favoráveis e ambientes ideais para avaliação. Portanto, o objetivo deste trabalho foi avaliar a interação genótipo por ambientes (G×A) de linhagens elite de feijão-caupi nos ensaios de valor de cultivo e uso (VCU) da Embrapa Meio-Norte, realizados nas regiões de Cerrado do Brasil, por meio de analises via GGE Biplot. Avaliou-se a produtividade de grãos em 40 genótipos de feijão-caupi, sendo 30 linhagens e 10 cultivares, durante três anos (2010, 2011 e 2012) em três locais: Balsas (BAL), São Raimundo das Mangabeiras (SRM) e Primavera do Leste (PRL). Os dados foram submetidos a análises de variância, a partir da qual foram obtidas as médias ajustadas para realizar a análise via GGE-Biplot. Os resultados gráficos revelam que houve variação no comportamento dos genótipos nos locais avaliados ao longo dos anos. As linhagens MNC02-675F-4-9 e MNC02-675F-4-10 apresentaram desempenhos de um genótipo ideal, com máxima produtividade aliada à boa estabilidade nos locais de avaliação. Houve a formação de três mega-ambientes que englobaram ambientes correlacionados positivamente. As linhagens MNC02-675F-4-9, MNC02-675F-9-3 e MNC02-701F-2 apresentaram o melhor desempenho médio dentro de cada mega-ambiente. O ambiente PRL10 e as linhagens próximas a este ambiente, como MNC02-677F-2, MNC02-677F-5 e a cultivar testemunha BRS-Marataoã, puderam ser classificados com maior confiabilidade, determinados basicamente pelos efeitos genotípicos, com G×A reduzida. A maioria dos ambientes avaliados foram ideais para avaliação da G×A, discriminando bem os genótipos. Portanto, a análise GGE-Biplot, permitiu selecionar genótipos com adaptabilidade e desempenhos superiores para ambientes específicos.

ABSTRACT The GGE Biplot method is efficien to identify favorable genotypes and ideal environments for evaluation. Therefore, the objective of this work was to evaluate the genotype by environment interaction (G×E) and select elite lines of cowpea from genotypes, which are part of the cultivation and use value tests of the Embrapa Meio-Norte Breeding Program, for regions of the Brazilian Cerrado, by the GGE-Biplot method. The grain yield of 40 cowpea genotypes, 30 lines and 10 cultivars, was evaluated during three years (2010, 2011 and 2012) in three locations: Balsas (BAL), São Raimundo das Mangabeiras (SRM) and Primavera do Leste (PRL). The data were subjected to analysis of variance, and adjusted means were obtained to perform the GGE-Biplot analysis. The graphic results showed variation in the performance of the genotypes in the locations evaluated over the years. The performance of the lines MNC02-675F-4-9 and MNC02-675F-4-10 were considered ideal, with maximum yield and good stability in the locations evaluated. There mega-environments were formed, encompassing environments correlated positively. The lines MNC02-675F-4-9, MNC02-675F-9-3 and MNC02-701F-2 had the best performance within each mega-environment. The environment PRL10 and lines near this environment, such as MNC02-677F-2, MNC02-677F-5 and the control cultivar (BRS-Marataoã) could be classified as those of greater reliability, determined basically by the genotypic effects, with reduced G×E. Most of the environments evaluated were ideal for evaluation of G×E, since the genotypes were well discriminated on them. Therefore, the selection of genotypes with adaptability and superior performance for specific environments through the GGE-Biplot analysis was possible.

RESUMO Os efeitos da interação genótipos por ambientes podem ser reduzidos, utilizando-se cultivares com ampla adaptabilidade e boa estabilidade produtiva. O estudo desse tema possibilita a identificação de genótipos de comportamento previsível e que sejam responsivos às variações ambientais, em condições específicas (ambientes favoráveis ou desfavoráveis) ou amplas. Este trabalho foi realizado com o objetivo de avaliar a adaptabilidade e estabilidade fenotípica de linhagens elite de feijão-caupi de porte semiprostrado na região de Cerrado do Brasil. Foram avaliados vinte genótipos de feijão-caupi em nove ensaios VCU (Valor de Cultivo e Uso) de porte semiprostrado, no período de 2010 a 2012. Os dados de produtividade de grãos foram submetidos a análises de variância e em seguida a análises de estabilidade e adaptabilidade pelos métodos de Eberhart e Russell (1966), Lin e Binns (1988) modificado, Wricke (1965) e Annicchiarico (1992). A metodologia de Wricke (1965) demonstrou ser pouco informativa, por indicar apenas a contribuição de cada genótipo para a interação genótipo × ambiente. Os resultados obtidos pelos métodos Lin e Binns (1988) modificado, Annicchiarico (1992) e Eberhart e Russell (1966), foram mais informativos, sendo coincidentes em indicar o cultivar BRS Xiquexique e as linhagens Pingo-de-Ouro-1-2, MNC02-676F-1, MNC01-649F-2-1 e MNC02-677F-2 como os mais promissores. Essas linhagens possuem potencial para lançamento como cultivares, por apresentarem adaptabilidade e estabilidade produtiva na região do cerrado brasileiro.

ABSTRACT The effects of the genotype × environment interaction can be reduced by using cultivars with high adaptability and good yield stability. Studies on this subject allow identification of genotypes of predictable behavior, and responsive to environmental variations in specific and general conditions, in favorable or unfavorable environments. The objective of this work was to evaluate the adaptability and phenotypic stability of cowpea elite lines of semi-prostrate growth habit in the Cerrado biome in Brazil. Twenty cowpea genotypes of semi-prostrate growth habit were evaluated in nine VCU (value for cultivation and use) tests from 2010 to 2012. Grain yield data were subjected to analysis of variance, and stability and adaptability analyses were carried out by the methods of Eberhart and Russell (1966), Lin and Binns (1988) (modified), Wricke (1965), and Annicchiarico (1992). The method of Wricke (1965) was not very descriptive, since it indicates only the contribution of each genotype to the genotype × environment interaction. The results obtained by the methods of Lin and Binns (1988) (modified), Annicchiarico (1992) and Eberhart and Russell (1966) were more descriptive, and similar in indicating the most promising cultivar (BRS-Xiquexique) and lines (Pingo-de-Ouro-1-2, MNC02-676F-1, MNC01-649F-2-1 and MNC02-677F-2). These lines have potential for the development of new cultivars because they present adaptability and yield stability in the Cerrado biome of Brazil.