ABSTRACT The knowledge of correlations between multiple characteristics in plant breeding leads to more effective selection strategies. The path analysis allows refining these correlations and partitioning them into direct and indirect effects on the main variable. The path analysis becomes more effective when based on predicted genotypic values rather than phenotypic values. The objective was to evaluate correlations between the main agronomic characteristics of grapevine cultivation and their direct and indirect effects on yield per plant to improve selection strategies to reach superior progenies. A randomized complete block design was installed using four cultivars and two rootstocks, five repetitions, and plots of four plants. Data from three crop seasons were analyzed from a mixed model and genetic correlations were subject to the path analysis. A high and positive significant correlation was found between average fruit production and the number of clusters per plant. On the other hand, the average production per plant showed a low correlation to cluster width and height per grapevine. Wider and higher berries tend to increase berry fresh mass and therefore increase the contents of soluble solids and reducing sugars. Among the features, the number of clusters per plant has the strongest direct effect on fruit production in grape cultivars. Berry fresh mass, berry length, and berry width were indirectly influenced by the number of clusters and showed high heritability compared to yield and number of clusters. These characteristics could be used in indirect selection. variable progenies rootstocks repetitions plants hand sugars features length

ABSTRACT. Evaluation of combined ability can eliminate lines that are inefficient and enable the subsequent program steps to be more successful. The objective of this study was to predict the general (gi) and specific (sij) combination ability of popcorn S1 progenies for early selection. A total of 288 topcrosses were performed under a randomized complete block design with two replicates at two sites (Campinas and Capão Bonito, São Paulo State, Brazil). Diallel analyses were performed using mixed models and the maximum likelihood restricted/best unbiased linear prediction method. Evaluated traits included grain yield (GY; kg ha-1), weight of 100 grains (g), and popping expansion (PE; mL g-1). Ear components were also evaluated, including ear length, ear diameter (cm), and the number of grain rows (unit). The S1 progeny 32 presented the highest gi for GY in Campinas, whereas progeny 46 presented the highest gi for GY in Capão Bonito. The S1 progeny, 114 was an important parent for the popcorn breeding program, because it presented high gi for the traits of agronomic interest at both sites. Combination 86×IAC12 exhibited a high sij, and the 86 parent presented the second-highest gi for PE in Campinas, and it should be used for high PE genotypes.

RESUMO Na época do plantio de milho safrinha ocorre maior instabilidade climática, com maior probabilidade de ocorrência de períodos de déficit hídrico. Este é um dos fatores que mais causa redução na produtividade de grãos de milho. O objetivo deste trabalho foi identificar genótipos de milho tolerantes ao déficit hídrico, estáveis e responsivos à irrigação. Avaliaram-se 26 híbridos intervarietais convencionais de milho, em experimentos realizados em Mococa/SP e Tatuí/SP, no Instituto Agronômico. Em cada local foram conduzidos dois ensaios, um sob condições de irrigação e outro sob estresse hídrico, em delineamento experimental de blocos casualizados com 3 repetições. Foram avaliados: florescimentos masculino e feminino, alturas da planta e de espiga, peso hectolítrico, peso de cem grãos e produtividade de grãos. Foi realizada análise de variância conjunta e a estabilidade foi analisada pelo GGEBiplot. Observaram-se efeitos de genótipos e local significativos para todas as características e efeitos significativos da interação genótipos x locais, exceto para altura de espiga e florescimento masculino. Já o efeito de condições hídricas foi significativo para a maioria dos caracteres, fato essencial para a viabilidade do trabalho. As características mais afetadas pelo déficit hídrico foram florescimento masculino, altura de plantas e de espigas e a produtividade de grãos. Os híbridos F2 BM709 x PopTol 2, IAC 46 x PopTol 2, F2 30K75 x PopTol 3 e F2 BM709 x PopTol 3 são considerados ideótipos por apresentarem elevada produtividade, plasticidade fenotípica e tolerância à seca, podendo ser indicados para programas de melhoramento genético visando tolerância à seca.

ABSTRACT In the period of planting of second-season maize, there is high climatic instability with greater probability of occurrence of water deficit. This is one of the factors that most cause reduction in maize grain yield. In this context, the aim was to identify stable, irrigation-responsive and drought-tolerant maize genotypes. The experiments were conducted in Mococa / SP and Tatuí / SP, at Instituto Agronômico, in two assays, one under full irrigation conditions and the other under water stress. The experimental design was randomized blocks with 3 replicates. Male flowering, female flowering, plant height, ear height, hectoliter weight, one hundred grain weight and grain yield were evaluated. Joint analysis of variance and stability analysis were performed by the GGEBiplot method. Significant genotype and site effects were observed for all traits. Significant effects of genotype x site interaction were found for all traits except ear height and male flowering. The characteristics most affected by water deficit were male flowering, plant and ear heights and grain yield. Genotypes F2 BM709 x PopTol 2, IAC 46 x PopTol 2, F2 30K75 x PopTol 3 and F2 BM709 x PopTol 3 are considered ideotypes because of their high grain yield, phenotypic plasticity and drought tolerance.

RESUMO Dentro dos programas de melhoramento torna-se necessária a avaliação da eficiência de seleção dos genótipos ao longo dos anos. Entretanto, avaliar essa eficiência nem sempre é uma tarefa fácil. Uma vez que não existe uma abordagem única, além disto, os programas de melhoramento necessitam ser dinâmicos com a adição e descarte de genótipos ano a ano. Como resultado tem-se ao final dados muito desbalanceados, o que pode trazer dificuldades para a análise dos dados. Assim, objetivou-se propor abordagens para verificar o progresso genético do experimento Preliminar do Programa de Melhoramento de Arroz de Terras Altas da Universidade Federal de Lavras (UFLA), para produtividade de grãos e altura de plantas. Os experimentos foram conduzidos em sete ambientes, ao longo de quatro safras com um total de 120 genótipos. Para a análise conjunta, em função do desbalanceamento dos dados, foi adotada a abordagem por meio de modelos mistos pelo procedimento de máxima verossimilhança restrita/melhor predição linear não viciada (REML/BLUP). Além de parâmetros genéticos e fenotípicos, foram obtidos também ganhos com a seleção, taxa de renovação (RR%), progresso genético e o dinamismo dos experimentos Preliminares. Foi verificada a eficiência na seleção de genótipos superiores para todos os anos, com ganhos genéticos favoráveis para a redução da altura média de plantas associada com altas produtividades.

ABSTRACT In the context of plant breeding programs, it is necessary to evaluate the efficiency of genotype selection over successive years. However, evaluating the genotype selection efficiency is not an easy task, since there is not just a single way to precede it. Besides that, the programs need to be dynamic; that is, they should be able to track the introduction and discard of genotypes each year. As a result, the available data is quite unbalanced, leading to difficulties in certain analyses. Thus, the present study aims to propose some approaches to verify the genetic progress in the preliminary trial of the Federal University of Lavras (UFLA) upland rice breeding program. We utilized mixed models for grain yield and plant height. Trials were performed with a total of 120 genotypes in seven environments, defined by the interaction between locations and years. Due to the imbalance in the available data, the mixed model approach, i.e., Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP), was adopted for the joint analysis. Besides the genetic and phenotypic parameters, the expected gains were also obtained with the selection, genetic progress, renewal rate (RR%), and dynamism of preliminary trials. The efficiency of the selection of superior genotypes per year was verified, with genetic progress favorable for reducing the medium-sized plants associated with high yield.

ABSTRACT Brazil is one of the leading countries in the production of maize (Zea mays), with great potential for growing green maize, which has a superior commercial value in relation to maize marketed in the form of grains. Although important, the availability of cultivars recommended for the production of green maizeis still very scarce. The objectives of the present study were to estimate genetic parameters and to identify promising hybrid combinations for the development of new green maize cultivars to farmers. In the summer crop of 2016/17, ten hybrid combinations obtained through a complete diallel of five maize populations, with attributes for in natura consumption, were evaluated in two sites of the state of São Paulo, Brazil: the Instituto Agronômico(IAC) in Campinas and Tatuí. A randomized block design was used with two additional checks, with three replications, in plots with four five-meter rows spaced by 0.9 m in Campinas and 0.8 m in Tatuí, with 5 plants per meter. The following agronomic traits were assessed: grain yield, ear yield with straw and ear yield without straw, using Griffing’s method 4. Significant effects of genotypes, environments and interaction genotypes × environments were detected for all traits. Estimates of the general combining ability led to the selection of populations P2, P4, and P5 as the ones with a higher concentration of favorable alleles for the characters evaluated. Estimates of specific combining ability and improved grain yield performance allowed P2xP3 to be selected as the most promising for production of green maize.