水稻不定根的穿鞘生长现象及其与叶片衰老的关系

Growth Phenomenon of Adventitious Root Penetrating Through the Base of Sheath and Its Effects on Leaf Senescence in Rice

从水稻根系形态学角度研究了水稻根系与叶片衰老的关系。发现在水稻根生长过程中伴随着根穿鞘现象,该现象影响到叶片的衰老进程。对 300 余个品种的考察分析表明,根发生的节位与功能叶片数量密切相关,发根节位越高,齐穗期功能叶片越少。齐穗期水稻地上部不发根节的数量与绿叶数量呈极显著正相关(r=0.8457),直线回归方程是 y=0.0045+0.9756x。推测根穿鞘生长对叶片造成的损伤及营养竞争是导致和加速叶片衰老与死亡的直接原因;高节位根生长和根数量过多是杂交水稻叶片早衰的重要原因。提出控制根数量、适当增加分枝根数目和加深根分布是未来开展水稻根系育种、塑造水稻理想根型的基本方向。

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.