Abstract:

To understand the grain weight variation with climatic factors and exert its ecological potential of grain yield for a two-line hybrid rice Liangyoupeijiu, grain weight was carefully calculated with dissected indices of grain length, width, thickness and specific gravity. In an effort to correlate ecological factors to such indices during growing stages, a set of data from eight ecological plots in Southern China rice area in 2006 and 2007 were used to establish ecological model. Equations with climatic and biological factors were established for grain area (S), thickness (H) and specific gravity (ρ). Correlation analysis showed that growing stages strongly affected S from glumes differentiation (stage III–IV) to pollen mother-cell meiosis (stage VI–VII), and the most important meteorological factor was temperature. Furthermore, daily average temperature ( ) of 27–29℃, daily maximum temperature (T_max) of 34℃，and daily minimum temperature (T_min) of 24℃ were favorable to growth in grain length and thickness. Thickness showed quadratic relation with Tmax and linear negative relation with at 1–30 d after heading. Specific gravity positively correlated with sunshine hours (SH) during 1–10 d after heading, and negatively correlated with Tmax during 1–30 d after heading, and 8 h of SH, Tmax<30℃ were favorable to the development of ρ. By modeling with climate data of 95 cities which was grouped into seven rice cropping areas in Southern China during 1951–2002, the mean 1000-grain weight of Liangyoupeijiu was 25.93–28.01 g, which mainly varied with the latitude. However, grain weight in Hunan, Jiangxi and Guangdong Provinces was presented a certain extent of varying trend with longitude because of the tremendous difference of altitude. 1 000-grain weight of late season rice was 1.39 g larger than that of early season rice. The key factors affecting the ecological and seasonal characters of grain weight were temperature during panicle differentiation, subsequently, the temperature and sunshine hours during grain filling period.

Key words: Liangyoupeijiu, Grain weight, Climatic factor, Model, Ecology