Abstract:

【Objective】 Many studies on the source-sink characters of high-yielding combinations of main crop or ratooning rice, but there were few studies on high-yielding combinations total yield of main crop and ratooning rice. In this paper, the relationship between the decreased index of SPAD value of leaf from full heading to harvesting (DISVLFHH) and ratooning ability,the plant characters of main crop for high yielding combinations of main crop and ratooning rice were studied, which could provide a theoretical and practical basis for improvement of high yield breeding and cultivation of hybrid rice. 【Method】 The experiment was conducted with eighteen mid-season rice combinations grown in a traditional high yield cultivation system, in a randomized block design with 3 replications. The results were analyzed through variance, correlation, regression and path analysis. 【Result】Alive bud rate, born bud rate, effective panicles and grain yield of ratooning rice were the key traits of ratooning ability, which was a an important approach for further high yield of ratooning rice by increasing effective panicles.There were significant or highly significant relationships between spikelets per panicle,the ratio of leaf area to spikelets, the ratio of leaf area to grains, the ratio of leaf area to grain weight, decreased LAI index, DISVLFHH of main crop and alive bud rate, born bud rate, effective panicles, grain yield of ratooning rice, and the partial correlation coefficient between only DISVLFHH among all trais and alive bud rate, born bud rate, effective panicles, grain yield of ratooning rice got significant at 0.05 level. As for one variety, it’s impossible that both main crop and ratooning rice could get top grain yield. The high-yielding combinations for 11.5t per ha of the theory grain yield and 14t per ha of potential grain yield for main crop and ratooning rice would have the following source-sink characteristics: 160-190 spikelets per panicle, the ratio of leaf area to grain weight 0.0737-0.0827 cm2 per mg , DISVLFHH 0.4029-0.5409, effective panicles 232.12×104-249.40×104 per ha, seed setting percentage 81.54%-85.74%, 1000-grain weight 28.58-30.07 g, grain weight 4.13-4.43 g per panicle. 【Conclusion】 Increasing effective panicles is an important approach for further high yield of ratooning rice, DISVLFHH of main crop can be used as a new evaluation index for ratooning ability,and the combinations with middle-big spikelets per panicle are the key characteristic for selection of mid-season rice hybrids for high yield of main crop and ratooning rice.

Key words: mid-season hybrid rice, ratooning ability, index decreased of SPAD value, plant characters