ABSTRACT
Summary Stylosanthes guianensis (Aubl.) Sw. shows wide variations in morphological and physiological characteristics, and basic information on genetic variability is needed for future breeding programs. The objectives of this paper were to evaluate 25 native Brazilian populations of S. guianensis for forage characteristics and to estimate genetic and phenotypic parameters for these characters. The experiment was conducted in a duplicated 5 x 5 balanced lattice design with plots that contained 4 individuals spaced on 2-m centers. The following characters were evaluated after the beginning of flowering period: days to flowering (DF), mean diameter (MD), basal area (BA), growth habit (GH), foliage (F), and green- and dry-matter yields (GMY and DMY). Genetic differences among populations were detected for all characters. Coefficients of genotypic determination indicated that GH and DF should respond readily to selection but improvement of GMY and DMY would be more difficult. The correlations between means and intrapopulational variances indicated the existence of populations with high means and variances for MD, BA, GMY, and DMY. For GH the correlation (r = - 0.530) indicated that the erect populations were less variable than the prostrate populations. Correlations between populations means for pairs of characters were positive and significant for the 6 correlations between GMY, DMY, MD, and BA. All 9 other correlations were negative. Only the correlations of F with MD and BA were negative and significant. Therefore, it would be possible to improve DMY indirectly by selecting for increased GMY, MD, and BA, among which MD would be the preferred trait as it is easy to evaluate and has the largest coefficient of genotypic determination.
