Growth and yield response of five "super" rice (Oryza sativa L.) cultivars to nitrogen fertilizer rates

Yield formation and growth of “super” rice (Oryza sativa L.) was affected by nitrogen application, and the response of rice to nitrogen application varies with genotype, environment and management practices. In this study, five local typical rice varieties were used to study their yield formation and growth in response to nitrogen application in South China double cropping region. Field trials with three nitrogen rates (N 0, 187.5 and 225 kg ha -1 ) and five varieties were conducted in the experimental farm of South China Agricultural University in the early and late season of 2010. Rice yield and its components, aboveground total dry weight (TDW), crops growth rate (CGR), SPAD value, leaf area index (LAI), Plant height, agronomic Nuse efficiency (AE) and partial factor productivity of N fertilizer (PFP) were examined. The results showed that, N 187.5 kg ha -1 had the highest leaf area index at full heading, crop growth rate from full heading to maturity as well as total dry weight at maturity, which resulted in a significantly high increase in grain yield from 24.19-29.84% and 5.01-6.26% as compared to N 0 and 225 kg ha -1 , respectively, N 187.5 kg ha -1 showed a significant increase in agronomic N-use efficiency and partial factor productivity of N fertilizer by 38.80-61.14% and 24.30-27.42% as compared to N 225 kg ha -1 in both seasons. As for varieties, Fengmeizhan and Yuxiangyouzhan obtained higher yield of 7.33 and 7.04 t ha -1 in early and late season, respectively. The average grain yield was 4.44% higher in early rice than in late rice. It indicated that varieties showed difference in response to seasons, and application of N 187.5 kg ha -1 will get higher yield.