Physiological processes associated with high yield traits in modern rice varieties

Understanding the physiological processes associated with high yield traits in modern cropvarieties is essential to further increase grain yield and improve nutrient management strategies.Field trials were conducted to study the effects of fertilization and variety on the grain yield ofrice (Oryza sativa L.) with two fertilizer levels and 18 modern varieties. The objectives were toevaluate yield components, time courses of dry matter production and time courses of N, P2O5and K2O accumulation among different yield categories and to determine physiologicalprocesses associated with yield-trait relationships. Variation among varieties had a considerableimpact on rice grain yield, regardless of fertilization. Close correlations were observed betweengrain yield and effective panicles, dry matter production and N, P2O5 and K2O accumulation.Differences in dry matter production and P2O5 accumulation among different yield categoriesbegan at anthesis; differences in N and K2O accumulation emerged earlier. It can be concludedthat consistent increases in dry matter production (especially post-anthesis) and N, P2O5 andK2O accumulation are crucial for further improvements in rice yield-trait relationships.