Stover quality of dual-purpose sorghums: Genetic and environmental sources of variation

Abstract

Improvement of the nutritive value of dual-purpose sorghum (Sorghum bicolor (L.) Moench) stover is an important objective for the semi-arid tropics where sorghum crop residue is extensively used for livestock feed. To identify the relative importance of genetic and environmental sources of variation for nutritive value, leaves and stems of six diverse dual-purpose sorghum cultivars were evaluated for in vitro gas production (Gas48hr), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, nitrogen, and ash contents under two fertility and two plant-density regimes during 2 years in India. Substantial genotypic differences were observed for stem Gas48hr (25.7 to 33.0 ml in 200 g-1 dry matter (DM)) and NDF (564¯687) content. Gas48hr and NDF content of stems exhibited more promise as selection criteria than those of leaves, as stems showed larger portion of variation attributed to genotypes, relatively less genotype by environment (GE) interactions, and were closely related to whole-plant values. Year, nitrogen fertilization and plant density showed very little influence on Gas48hr, NDF or ADF of leaves and stems. Gas48hr exhibited substantial GE interactions with all environmental factors, indicating the need for multi-environment testing to achieve progress.