2004 Volume 73 Issue 3 Pages 247-252
The effect of root pruning on transplanting injury was compared between the rice seedlings raised on cotton mats spread on a hydroponic culture solution with different nitrogen compositions (plots 1 and 2). The culture solution containing NH4-N : NO3-N = 28% : 72% (sol-1) was applied from 8 days after sowing (DAS) in both plots 1 and 2, but in plot 2 the culture solution containing NH4-N : NO3-N = 100% : 0% (sol-2) was applied instead of sol-1 from 15DAS. At the end of cultivation (21DAS), when the plant length and root length in plot 1 were 10% and 61%, respectively, longer than those in plot 2, the apical part of roots except basal 1 cm (group 1) or whole roots (group 2) were pruned. Then the seedlings were transplanted into holes of polystyrene foam attached to the hydroponic apparatus. Most of the growth parameters and dry matter weight were larger in group 1 than in group 2 in both plots 1 and 2, though the difference was smaller in plot 2. Root length at 5 and 10 days after transplanting was larger in plot 2 than in plot 1 in both groups. Plant length at 5 days after transplanting was longer in plot 1 than in plot 2 in both groups, but there was no distinctive difference at 10 days. Thus, the effect of root pruning on transplanting injury was comparatively weak at 5 and 10 days after transplanting and the recovery from the root pruning stress was better in plot 2.
