GENOTYPIC AND PHENOTYPIC CORRELATIONS IN A SOYBEAN CROSS

In a plant breeding program, an efficient selection of desired characters in a population is important. Generally, many agronomic characters in a given population are determined by polygenes and quantitatively inherited. In practice, the genetic relationship between two observed characters which are undoubtedly subjected to the environmental influence is difficult to identify. In recent years, many workers have attempted to understant the genetic relationship between characters in terms of genotypic correlation, and the knowledge thus gained should furnish many important and useful information for the planning of breeding, selection, and interpretation of the result. The genotypic correlation is the result of pleiotropy, linkage of genes(2, 3, 5, 6, 8) and natural or artificial selection(4). The purposes of this study were to estimate genotyric and phenotypic correlations between all possible pairs of nine characters. and to seek certain characters which may be useful as indicators of certain important agronomic characters. Weber and Moorthy(10), Johnson et al. (5) and Sheth(7) found that in general, the genotypic correlations were higher than the phenotypic correlations. Weiss et al. (11) obtained significant positive correlations between maturity and oil content, maturity and low protein content, and high protein content and low oil content. Weber and Moorthy(10) reported the positive genotypic correlations between flowering and maturity, yield and maturity, yield and plant height, yield and seed weight, and negative genotypic correlations between maturity and oil content, and oil content and seed weight. Johnson et al. (5) studied the genotypic and phenotypic correlations among 24 characters and concluded that selection based entirely on a long fruiting period, lateness, heavy seed, low protein, high oil and resistance to lodging would be effective in increasing yield. Sheth(7) found the following positive associations among characters; height and maturity, yield and lodging, low protein content and high oil content, and yield and low protein content. Hanson et al.(1) also reported high negative correlation between seed yield and protein content.