Agronomic performance of high-yielding rice variety grown under alternate wetting and drying irrigation

Alternate wetting and drying (AWD) irrigation has been proven to be an effective water-saving technology for irrigated rice system. There is limited information on the performance of super hybrid rice varieties under AWD conditions. This study was conducted to compare grain yield and other related traits between a super hybrid rice variety and a water-saving and drought-resistance rice (WDR) variety and to identify plant traits which were responsible for varietal difference in grain yield under AWD conditions. Yangliangyou 6 (YLY6, a super hybrid rice variety) and Hanyou 3 (HY3, a WDR variety) were grown under AWD and continuously flood-irrigated (CF) conditions across different levels of nitrogen input in Hubei, China in 2009 and 2010. Grain yield, yield attributes, total water input, water productivity, and nitrogen use efficiency were measured. AWD saved 24% and 38% irrigation water compared with CF in 2009 and 2010, respectively. There was insignificant difference in grain yield between AWD and CF. On average, YLY6 produced 21.5% higher yield than HY3 under AWD conditions. Like grain yield, YLY6 showed consistently higher water productivity and physiological nitrogen use efficiency than HY3. Both total dry weight and harvest index contributed to higher grain yield of YLY6. Among the yield components, large sink size which was caused by more spikelets per panicle was mainly responsible for high grain yield of YLY6 compared with HY3. These results suggest that high-yielding varieties developed for the continuously flood-irrigated rice system could still produce high yield under safe AWD experienced in this study. Super hybrid rice varieties do not necessarily require more water input to produce high grain yield. Increasing the number of spikelets per panicle should be a primary target of breeding high-yielding rice varieties for AWD conditions. (C) 2011 Elsevier B.V. All rights reserved.