Studies on transplanting injury in rice plant. III. Effects of root pruning treatment on the organic constituents in each organ and rooting of seedlings after transplanting.

Abstract

This study was undertaken to clarify the effects of root pruning on the organic constituents and early growth in each organ of seedling after transplanting, using 6 leaf aged seedlings without pruning roots (CS) or with pruning all roots (PS). The degree of transplanting injury was severer in PS than that in CS. Wilting of leaf blade and sheath in PS was conspicuous, and carbohydrate was scarcely accumulatcd as a whole after transplanting. Nevertheless, degradation of protein in the leaf blade and starch in the leaf sheath and stem was accelerated just after transplanting and non-protein nitrogen or sugars accumulated in the stem. The accumulation of these soluble substances in the stem promoted rooting of PS, so that there was little difference in taking roots relative to CS which markedly accumulated carbohydrate, especially sugars, in not only the stem but also in the leaf sheath just after transplanting. Moreover, root dry weight of PS recovered by 37% of CS untill 14 days after transplanting. However, growth and development of tiller buds of PS was inhibited, due to partitioning of most of the carbohydrate and nitrogen for the formation of new roots. Consequently, the dry weight in top organs decreased 35-40% as compared with CS during 8-14 days after transplanting by less development of leaf area of the tillers.