Studies on transplanting injury in rice [Oryza sativa] plant, 7: Effects of antitranspirant and irrigation water depth on the transplanting injury, rooting and early growth
1990
Yamamoto, Y. (Kochi Univ., Nankoku (Japan). Faculty of Agriculture)
Using 6 or 7 leaf-aged seedling without pruning roots or with pruning roots to the different extent, the effects of spraying 4% water solution of antitranspirant [OED (Oxyethylene docosanol) Green] to the seedling just before transplanting and of irrigation water depth (0, 5, 10, 20cm) on the transplanting injury, rooting and early growth by the change of carbohydrate content in seedlings after transplanting were studied. Regardless of the extent of root pruning in seedling, the elongation rate of leaf on the main stem was accelerated by spraying the antitranpirant solution to the seedlings just before transplanting or deep irrigation water up to 20 cm after transplanting. This result shows that transplanting injury was decreased by the inhibition of transpiration due to the lowering of decrease of water content or silting of leaf blade, especially in seedlings with severely pruned roots. However, the development of new roots and tillers in these treated seedlings were depressed, because photosynthesis might be depressed concomitantly with transpiration and carbohydrate content in top part resulted in decrease as compared with that of non-treated seedlings, except the seedlings with completely pruned roots were promoted the rooting in parallel with the elongation rate of leaf up to 10 cm deep irrigation water due to the increase of carbohydrate content in top part. Consequently, these results suggested that the carbohydrate contained in top of seedling just after transplanting play a very important role for the rooting, as we reported in the previous paper, and moreover, the decrease of transplanting injury did not always resulted in the promotion of rooting or early growth in rice seedlings
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