Abstract
Rice seedlings are often injured during transplanting, mainly due to the damage to the roots, but plant growth recovers after newly emerged roots elongate. The morphological changes during the formation and emergence of crown roots from the rice seedlings with roots pruned by transplanting were examined. The roots of rice seedlings at the 3.2 leaf stage were pruned and serial cross-sections of the stems of the seedlings at the 7.2 leaf stage were observed under a light microscope. By root pruning, the stem length tended to be reduced but the diameters of stems and peripheral cylinder increased. The numbers of crown root primordia and emerged crown roots in every stem section were slightly increased by root pruning, but the diameter of the crown root was unaffected. These results indicate that the numbers of crown root primordia and emerged roots were increased by root pruning and that the number of roots increased gradually and continuously to promote seedling establishment after root pruning.
