Comparison of yield components and plant type characteristics of high-yield rice between Taoyuan, a 'special eco-site' and Nanjing, China

A number of field studies have reported very high rice yields in Taoyuan, Yunnan province, China, and the physiological and ecological factors associated with high yield have been explored. However, little attention has been paid to differences in plant type. The main objective of this study was to reveal the plant type characteristics associated with the high rice yield through the comparison of two sites: Taoyuan, Yunnan province and Nanjing, Jiangsu province, China. The physiological and environmental factors were also discussed. Field experiments were conducted at two sites in 2006 and 2007. Three Indica F₁ hybrid varieties, Eryou 107, Xieyou 107 and Eryouhang 1 in 2006, Eryou 107 and Xieyou 107 in 2007 were grown at two sites under optimum crop management to achieve maximum attainable yields. Leaf area, leaf length, leaf width, leaf angles, specific leaf weight (SLW) and specific leaf nitrogen (SLN) at heading, yield and yield components at maturity were determined. Daily radiation, air temperature and relative humidity (RH) were monitored. The highest yield of 18.5tha⁻¹ was achieved by Eryou 107 at Taoyuan in 2006, and average yield of all varieties at Taoyuan was 96% and 85% higher than Nanjing in 2006 and 2007, respectively. The higher yield at Taoyuan was attributed primarily to the larger sink size, which was mainly caused by the greater number of panicles per m². Biomass production was greater at Taoyuan than at Nanjing in 2006 and 2007, while differences in harvest index were very small. Compared with Nanjing, the rice planted in Taoyuan has greater leaf area index about 10 with smaller area per stem, shorter, wider and thicker leaves and smaller leaf angles. These results indicate that in addition to the higher biomass accumulation (main physiological factor) and the intense solar radiation with the large diurnal temperature range (main environmental factor), the greater leaf area index (LAI) with smaller area per stem, may be an important morphological factor contributing to the high yield in Taoyuan.