Yield attributes and nitrogen-use efficiency of “super” hybrid rice

摘要

China’s “super” rice breeding project has developed many F1 hybrid varieties using a combination of the ideotype approach and intersubspecific heterosis. These hybrid rice varieties have been grown commercially in China since 1998. They produced grain yield of 12 t ha–1 in on-farm demonstration fields, 8–15% higher than the hybrid check varieties. We conducted field experiments to compare the grain yield and yield attributes of “super” hybrid rice varieties over a wide range of N rates in Hubei and Hunan in 2004-07. A “super” hybrid rice variety showed higher yield potential than a conventional hybrid rice variety because of its higher biomass production, not harvest index. The higher biomass production was associated with greater leaf area duration. There was no difference between the “super” hybrid rice variety and hybrid check variety in radiation-use efficiency, suggesting that single-leaf photosynthetic rate was not the reason for the high yield potential of the “super” hybrid rice variety. Both the “super”hybrid rice variety and conventional hybrid variety required a minimum total N rate of 120 to 150 kg N ha–1 to produce maximum grain yield. There was no clear difference in N-use efficiency between the “super” hybrid rice variety and conventional hybrid variety. A three-line hybrid, SL-8H, has been widely grown in the Philippines since 2003. Morphologically, SL-8H has many similarities with China’s “super” hybrid rice. To increase rice yield potential in the tropics,we need to develop new plant type varieties similar to SL-8H with slightly more filled spikelets per panicle.