Abstract: An interesting phenomenon of root growth in rice has been observed. The phenomenon is that the roots emerged from the nodes consequentially penetrate the base of leaf sheath grown from the nodes where roots grow and below it as well. The results from experiments with 300 diverse cultivars showed that the number of non-rooting nodes and the number of green leaves in full-heading stage presented the positive correlation (r=0.8457), and the linear regression equation was y=0.0045+0.9756x. The results indicated that wounding made by root penetrating growth and contesting nutrition likely cause and accelerate leaf senescence, rooting at higher nodes and overmuch root numbers are an important reasons of leaf premature senescence in hybrid rice. It was supposed that proper root number, much branches and deep-root is a development direction of breeding for ideal type root system in rice.

Key words: Rice, Adventitious root, Penetrating growth, Leaf senescence