Agronomic performance of late-season rice in South China

Improving rice yields is critical for global food security. China is a major rice-producing country having two rice cropping systems, i.e. single-season rice cropping system and a double-season system with both early- and late-season rice. There have been reports on the sink-source traits contributing to high grain yield for single- and early-season rice, but such information is limited for late-season rice. In this study, field experiments were conducted at the research farm of Guangxi University, Nanning, Guangxi Province, China in the late rice-growing season. Grain yield and sink-source traits were compared among five cultivars (Guiliangyou 2, Teyou 838, Y-liangyou 087, Teyou 582, and Yuxiangyouzhan) in 2012 and then three cultivars (Guiliangyou 2, Teyou 838, and Y-liangyou 087) in 2013. Y-liangyou 087 produced 6–26% higher grain yield than did the other cultivars. This higher grain yield was driven by improvements in sink-source capacity. Sink capacity was 8–31% higher in Y-liangyou 087 than in the other cultivars. Well-balanced relations between spikelets m^?2 and grain weight was responsible for the higher sink capacity in Y-liangyou 087. The result was that Y-liangyou 087 produced 11–17% greater biomass (source capacity) than did the other cultivars. The greater source capacity in Y-liangyou 087 was mainly attributed to higher radiation use efficiency (RUE). Our study suggests that enhancing sink capacity through balanced relations between number of spikelets per unit land area and grain size, while improving source capacity through increasing RUE is a feasible way to achieve higher grain yield of late-season rice in South China.