Correlações entre caracteres como critério de seleção indireta, adaptabilidade e estabilidade em genótipos de soja

Abstract

Soybean [Glycine max (L.) Merrill] is a Fabaceae, which comes from China. Currently, it is widely grown in the world and in Brazil, as it is a source of oil and protein, very important in feeding in general. It is a valued product in commerce, considered a commodity. Soybean breeding programs are to obtain highly productive cultivars, associated with other features of interest, such as agronomic characters, resistance to pests and diseases, wide adaptation, obtaining better quality seeds, efficiency in the use of fertility, increased on oil and protein content. In this context, the knowledge of the correlation between characters is of great importance for the improvement as the selection of a character can positively or negatively influence another. During the breeding process to obtain new cultivars, one of the main difficulties to find cultivars widely adapted and stable is the occurrence of genotype x environment interaction. Thus, the aim of this study was to evaluate the correlation between agronomic characters, study soybean path analysis and the genotype x environment interaction, and establish adaptability and productive stability in soybean lines. For the study of correlations, the experimental design used was a complete randomized block with three repetitions and 35 genotypes, being 31 lines from the breeding program at Federal University of Uberlândia and four commercial cultivars (UFUS 7910, BRSGO 7560, UFUS Xavante, M-Soy 8866). The characters evaluated were: number of days to blooming, plant height at blooming, number of days to maturity, plant height at maturity, height of first pod, number of nodes on the main stem at maturity, number of pods with one, two and three grains per plant, total number of pods per plant, number of seeds per pod and grain productivity. The characters plant height at maturity and number of nodes at maturity showed positive and significant correlation between phenotypic and genotypic. The character of a hundred grains weight was positively correlated with grain productivity and combined with the high direct effect phenotypic and genotypic, therefore being useful for indirect selection in order to increase grain productivity in soybean. To study the adaptability and stability, the experimental design used was a complete randomized block with three repetitions and 18 genotypes, being 14 lines of the breeding program at Federal University of Uberlândia and four cultivars used as witnesses (Emgopa 316 UFUS Guarani UFUS Riqueza and M-Soy 8001). The UFUS-09-10 and UFUS UFUS-13 genotypes were considered to be widely adapted and stable in the environments tested, because they were thus classified in at least three methodologies analyzed. To favorable environments the UFUS-01-06 and UFUS UFUS-08 genotypes can be recommended, which were thus classified by three methodologies, studied. And to unfavorable environments are recommended UFUS-11-14 UFUS genotypes and cultivar Emgopa 316, which were thus classified by three methods. The use of more than one method can help and give greater confidence and safety on the recommendation of cultivars to the environments studied.