Simulating genotypic strategies for increasing rice yield potential in irrigated, tropical environments

Irrigated rice yield potential needs to be increased. A simulation model was used to examine the opportunities for doing so in the dry season of a tropical climate by altering durations of juvenile and panicle formation phases, specific leaf area, maximum leaf N concentration, spikelet growth factor and potential grain weight. The study was conducted for three levels of N management: Practices followed in breeder's screening plots; agronomic recommendations for high yield potential; and growth-rate-driven N uptake. The results revealed that IR72, the check cultivar, has a large yield potential that can be realized with better N management. No trait individually or in combination provides more than 5% advantage in yield in the level of management typically practiced by breeders. In such environments, even though genotypes may possess traits for higher yield potential, they will not be able to express them. The simulations predict that significantly higher rates of N input and precise timing are required to attain a grain yield potential greater than 10 t ha 1. If plant. If plant N status can be increased without lodging or disease problems, a significant increase in yield requires increased sink capacity, maintenance of high leaf N content and a longer grain-filling duration.