Preliminary study on super rice population sink characters

Chinese. 探索超级稻群体库容形成及其构成特征。以具有代表性的5个籼型超级稻为材料,用汕优63为对照,比较研究超级稻群体籽粒库容构成及特征。(1)不同试点的超级稻品种均显著或极显著比对照增产,群体颖花量的增加是产量增加的直接原因。培育大穗是超级稻扩大库容量、增加颖花量的主要途径,而增穗并不能扩增群体总颖花量。(2)大穗是通过两种途径协调实现的:一是增加一次枝梗数及其上的平均着粒数,二是增加二次枝梗数但稳定二次枝梗上的平均着粒数; 其中增加二次枝梗数及其总粒数是主要的; 超级稻在一、二次枝梗数增加的同时,通过稳定二次枝梗上的平均着粒数而增加一次枝梗上的平均着粒数,优化颖花分布,提高全穗结实率而增加单穗籽粒重; 超级稻单穗重达4.0 g 以上, 平均比对照增重10.9% 。(3)超级稻产量潜力高,最大库容达870 kg/667m2，显著高于对照,平均增幅近10%；但最高库容有效充实度在品种间、试点间变化较大,并无稳定优势,平均为80.3%，略低于对照，故因种因地栽培是实现超级稻稳定超高产的关键。超级稻在稳定适宜穗数的基础上通过协调增加一次枝梗数和二次枝梗数及其平均着粒数来增大穗型,通过优化一、二次枝梗上颖花分布来提高结实率从而增加单穗重。

English. The formation character of population grain sink and yield component of super rice was revealed. 6 indica hybrid rice cultivars(including Shanyou 63 as CK) were used as the experimental material to research the composition and characteristics of population grain. The results indicated that:(1) The average yield of 5 super rice cultivars grown in Dongahi, Xinghua and Changshu in Jiangsu Province was 700.4 kg/667m2 (from 678.9 kg/667m2 to 724.7 kg/667m2) and there was significant difference in the yield between experimental cultivar and CK. The higher number of total spikelets in the population was a major and direct factor resulting in higher yield. Thus, the breeding of large panicle-size super rice with more spikelets increased the population grains and resulted in more panicle-size plants. (2) The large panicle was constructed by means of two ways: the first increased the number of primary branches(PB) and its number of grain-setting per PB. The other, the number of secondary branch(SB) was enhanced based on the stable number of grain-setting per SB, in which, the increment of number of SB and total number of grain-setting per plant was a key measure. It is very important in super rice with high yield to increase the number of PB and SB based on the stable number of grain-setting in SB and the maximum number of effective spikelet PB, so that the distribution of spikelet could be optimized for higher rate of seed-setting and more weigh seed per panicle. The average weight of seed per panicle of super rice was 4.0 g, 10.9% higher than that of CK. (3) The peak capacity of the sink of super rice was about 870 kg/667m-1, which was significantly higher than that of CK. There was wide variation of the effective filling rate of sink among varieties and experimental spots. The average effective filling rate of sink of super rice was 80.3% and 20% potential grain yield could be developed through the reasonable cultivation technique. The coordination of distribution and number of PB and SB for large panicleas well as the enhancement of the rate of seed-setting and the weigh of seed per panicle could be the effective approach to produce super rice with higher yield. It could be developed at the base of the stable and suitable panicle number in rice population.