Productivity and Eco-physiological Characteristics of Late Japonica Rice in Double-Cropping System

Abstract

In the condition of high yield cultivation, a field experiment was conducted with representative japonica rice cultivars(Wuyunjing 24, Nanjing 44, Zhendao 11, Changyou 1, Changyou 5, Yongyou 8) and the typical local late indica rice cultivars in double-cropping areas(Poyang and Shanggao in Jiangxi Province). Differences of grain yield, quality and net income between japonica and indica were studied systematically. The productivity advantages and its mechanism of late japonica rice were explained from the effects of temperature and light, plant type, and photosynthesis. Results showed that the average yield of late japonica rice in three years was 9.6, 8.3, and 9.9 t ha–1 in 2011, which was higher than that of indica rice significantly. The highest yield of Yongyou 8 in 2011 was 10.6 t ha–1. The grain number per panicle, seed-setting rate of japonica rice were higher than those of indica rice, which was the reason of higher yield of japonica rice. Milling quality, cooking and eating quality of japonica rice were also better than those of indica rice significantly, while appearance quality showed an opposite tendency. The brown rice rate, milled rice rate, and head rice rate of japonica rice were significantly higher than those of indica rice, while the amylose content, protein content of japonica rice were significantly lower than thaose of indica rice. And the gel consistency of japonica rice was also longer. The appearance quality including chalky grain rate, chalkiness area and degree of japonica were significantly higher than those of indica rice. The benefits of late japonica rice were significantly higher than those of indica rice, with the net income of 11 890.6, 10 252.1, 16 565.9 Yuan ha–1 in these years, respectively, which were higher than those of indica rice by 23.8%, 23.6%, and 26.7% respectively. The physiological and ecological characteristics of productive advantages of late japonica rice in double-cropping rice area were as follows. Firstly, growth duration of japonica rice was longer than that of indica rice significantly and japonica rice was more adapted to grow in cool weather at the later period of grain filling, increasing utilization of temperature and solar radiation and ensuring maturity safely. Secondly, strong photosynthetic capacity of japonica rice at the later period increased dry matter accumulation and total grain filling. Thirdly, japonica rice improved resistances to cold, premature senescence, and lodging due to strong root, stem and sheath.