DIALLEL CROSS ANALYSIS OF STOMATAL DENSITY AND LEAF-BLADE AREA IN GRAIN SORGHUM, SORGHUM BICOLOR

Analysis of a 6-variety diallel revealed that general and specific combining abilities were highly significant for stomatal density and leaf-blade area in Sorghum bicolor (L,) Moench. Interactions of genotype × location were also highly significant for both characters. For stomatal density, overdominance was indicated and one gene (or one block of genes) was involved; heritability estimate was 51%. For leaf-blade area, again overdominance was indicated and at least one gene controlled that trait; estimate of heritability was 18%. Regression coefficients of Wr on Vr of both characters deviated slightly from unity which could be due to epistasis or correlated gene distribution, or both. Dominance order of the parents was KS 9, Redlan, Combine Kafir 60, KS 18, KS 24, and Martin for stomatal density and KS 9, Martin, Redlan, KS 18, KS 24, and Combine Kafir 60 for leaf-blade area. The significant interaction of general combining ability × location and the highly significant interaction of specific combining ability (sea) × location for stomatal density and the highly significant interaction of sea × location for leaf-blade area imply that the breeding program attempting to improve these characters should tend toward producing individual lines for each different environment.