Two field experiments were conducted with dryland sorghum to understand the physiological basis of grain yield compensation at low plant density. The effects of plant density variation on leaf area develop ment, dry matter partitioning during grain filling, and grain yield components were studied. Compensation was more in reproductive than in vegetative organs. At low plant density, larger panicle per plant at anthesis ensured greater sink capacity. Both number of grains per panicle and single grain weight increased. The plants had higher proportion of flag leaf area in total leaf area and more efficient leaves (more number of grains per unit leaf area). Higher sink intensity in early period of grain growth, and greater mobilisation of assimilate from stem during grain filling contributed to larger grains than those of plants at high density.
