Relationships between grain yield and agronomic traits of rice in southern China

Field experiments were conducted to evaluate the grain yield and agronomic traits of inbred and hybrid rice (Oryza sativa L.) 'Yuxiangyouzhan' and 'Shenliangyou 58 xiangyouzhan' at 11 different planting sites during 2013-2017 in Southern China. The grain yield, growth period, panicle number m(-2) , productive tiller percentage, plant height, panicle length, grain number per panicle, filled grain number per panicle, filled grain percentage, and grain weight were evaluated. Results indicated that Shenliangyou 58 xiangyouzhan' produced higher grain yields than 'Yuxiangyouzhan' which was attributed to high grain weight and panicle length. Grain yield showed an increasing trend during 2013-2017 and the yield gaps among different years were attributed to differences in plant height, filled grain percentage and grain weight. The differences in grain yield among sites were mostly due to the combination effect of the agronomic traits which was greatly affected by the different climate conditions. The grain yield was significantly and positively correlated with the plant height, grain number m(-2), filled grain number per panicle, filled grain percentage and grain weight. Moreover, principal components analysis (PCA) suggested that grain number per panicle and filled grain number per panicle are critical parameters attributed to grain productivity. Therefore, flowering and post-flowering stage is the most critical in this regard to improve the grain number and filled grain number per panicle to get better yields in the agro-climatic conditions of southern China.