Crop developmental process and in turn its growth phases (vegetative and reproductive) are influenced by environmental factors, i.e. temperature and photoperiod in field crops like sorghum. Crop growth and biomass production is a function of genotype by environment interaction, which is optimized through management strategies. Crop grain yield is determined as a product of its yield components like the grain numbers per plant and the average kernel weight at maturity. Grain numbers set at the panicle initiation phase can be enhanced by best matching the supply of nitrogen with its demand in the crop. Grain growth dynamics, a function of genotype by environment by management interaction is an important feature that enhances sorghum productivity.
Rabi sorghum growing environment presents a challenge through a receding soil moisture front which decreases its response to applied external inputs like nitrogen (N) fertilizer. Deep placement of top dressed nitrogen fertilizer treatments increased rabi sorghum grain yield by about 630-930 kg ha-1 over farmers, practice of no fertilizer application. A management strategy helped enhance the agronomic nitrogen use efficiency to 16 kg grain per kg applied N, and the rain water use efficiency to 15 kg ha-1 mm. Thus, the hypothesis of increased rabi sorghum productivity per rain drop through improved management intervention in vertisols was validated.