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SUMMARYField experiments were conducted in 2005 and 2006 to investigate the impacts of alternative rice cultivation systems on grain yield, water productivity, N uptake and N use efficiency (ANUE, agronomic N use efficiency; PFP, partial factor productivity of applied N). The trials compared the practices used with the system of rice intensification (SRI) and traditional flooding (TF). The effects of different N application rates (0, 80, 160 and 240 kg ha−1) and of N rates interacting with the cultivation system were also evaluated. Resulting grain yields with SRI ranged from 5.6 to 7.3 t ha−1, and from 4.1 to 6.4 t ha−1 under TF management. On average, grain yields under SRI were 21% higher in 2005 and 22% higher in 2006 than with TF. Compared with TF, SRI plots had higher harvest index across four fertilizer N rates in both years. However, there was no significance difference in above-ground biomass between two cultivation systems in either year. ANUE was increased significantly under SRI at 80 kg N ha−1 compared with TF, while at higher N application rates, ANUE with SRI was significantly lower than TF. Compared with TF, PFP under SRI was higher across all four N rates in both years, although the difference at 240 kg N ha−1 was not significant. As N rate increased, the ANUE and PFP under both SRI and TF significantly decreased. Reduction in irrigation water use with SRI was 40% in 2005 and 47% in 2006, and water use efficiency, both total and from irrigation, were significantly increased compared to TF. With both SRI and TF, the highest N application was associated with decreases in grain yield, N use efficiency and water use efficiency. This is an important finding given current debates whether N application rates in China are above the optimum, especially considering consequences for soil and water resources. Cultivation system, N rates and their interactions all produced significant differences in this study. Results confirmed that optimizing fertilizer N application rates under SRI is important to increase yield, N use efficiency and water use efficiency.

Plastic film mulching cultivation under non-flooded condition (PFMC), a new high-efficiency and watersaving cultivation technique, has been adopted and developed in many regions of china since the 1980s. Field experiments were conducted to evaluate the effects of PFMC on rice quality in three agro-ecosystems (plain, basin and mountainous area) in 2001. The experiment consisted of three treatments, which were conventional flooded cultivation (CFC), PFMC and non-mulching cultivation (NMC) under non-flooded condition in a randomized complete block design with three replications. Compared with CFC, PFMC increased head-milled rice recovery (with the exception of plain area), rice transparency and alkali spreading value, but slightly decreased gel consistency and obviously decreased chalky grain rate. Compared with NMC, those quality traits under PFMC were changeable at different sites. There were no significant differences for brown rice rate (except hilly area), milling rice quality and amylose content across treatments. In addition, nutritional quality under PFMC was notably improved in comparison with CFC and NMC. With few exceptions, the protein content, total amino acid content, individual amino acid content and Lys content of rice decreased in the order of PFMC > NMC > CFC. In general, rice quality is affected by each agro-ecosystem and cultivation system to different degrees. PFMC had more influence on rice quality in hilly region than plain and basin regions.

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