Strategies for improving rabi sorghum productivity.

In India, sorghum (Sorghum bicolor(L.) Moench) grown during the postrainy season (rabi sorghum) accounts for nearly 40% of the total sorghum hectarage in the country. It is an important grain and fodder crop on 6.5m hectares on Vertisols in south-central India. Efforts to improve rabi sorghum yields have not resulted in any significant gain as they have for the rainy season sorghum. Continuously receding soil moisture, poor nutrient availability, and low night temperatures are some of the major reasons for the low yields. Rabi sorghum environments are diverse. They are inadequately characterized especially from the angle of recommending new genotypes. This paper reviews pertinent literature and summarizes results from the authors' studies relating the environmental factors during rabi to crop growth, development, water use, and grain yield. It also examines plant physiological traits of rabi sorghum likely to be useful for effective utilization of resources under stored soil-moisture conditions. Finally, suggestions are made on research directions for stabilization of rabi sorghum yields at higher levels. They include better characterization of environments, search for unique phenological response and root growth pattern.