Early Tillers At Low-nodes And Their Association With Seeding Morphological Characters And Carbon-nitrogen Metabolism In Rice

Rice grain yield is determined by three main components: panicle number per plant,grain number per panicle and 1000-grain weight.Among this,panicle number per plant is largely determined by the number of tillers per plant.Rice tillering,an extremely important agronomic traits,is not only influenced by external environmental conditions,but also regulated by endogenous physiology and biochemistry,hormones,genes and so on.The tillers at low-nodes in rice have great potential to increase effective panicles and crop yield.In order to study early tillers at low-nodes and their association with leaf morphological characters and carbon-nitrogen metabolism,and to screen rice varieties(lines)with more early tillers at low-nodes,high tillering rate and the leaf morphology of ideal plant architecture,we studied the tillering characteristics at early low-nodes,seeding leaf morphology and carbon-nitrogen metabolism indexes in 31 indica rice varieties(lines).And then correlation analysis and cluster analysis were carried out.The results were as follows:1.Under general cultivation conditions,the rice varieties(lines)showed extensive variation in tillering rate at the first node,while their tillering rate of the second and third nodes reached about 100%.The difference of early tiller in the different rice varieties(lines)was mainly reflected in the first node.2.Tiller number and the occurrence rate of tillers at low-nodes in rice were positively correlated with seeding leaf length and negatively correlated with leaf width.Therefore,in breeding,the first three leaves of rice seedlings which are longer and narrower could be used as morphological reference indexs for selection of rice varieties with more early tillers.3.The sucrose content in rice seeding affected only the occurrence rate of tiller,but not tiller number.Nitrate content affected not only the occurrence rate of tillers,but also tiller number.The activity of nitrogen metabolic enzymes such as NADH-GOGAT and NADH-GDH could promote the formation of tillers at low-nodes in rice.4.The rice varieties(lines)investigated in the current study were clustered into three categories: classes A,B and C.Among them,the class C was consisted of the cultivars with early tillers,fast occurrence rate of tiller,and leaf morphology closer to that of ideal plant architecture.