Abstract
The role of roots on the head formation posture in cabbage was studied by root pruning carried out at various growth stages and in different degrees before head formation.
1. Root pruning affected both the nastic movement of leaves and the leaf shape index (length/width), but did not affect leaf area in plants sown on Nov. 27. Namely, the ratio of length to width was lowered and the leaf hyponasty and rolling of inner leaves were promoted.
2. The roots of cabbage plants, sown on April 14, were pruned on May 22, June 1 and 11 to about halves, and also the roots of the other plants were pruned to 1/4, 2/4, and 3/4 respectively on June 1.
It was shown that the head formation posture was not hastened by both early and mild root pruning as compared with the control plants, although the temporary lowering of leaf shape index and promotion of leaf hyponasty in young leaves were found. However, it was remarkably promoted by both later and more severe root pruning.
3. The role of roots on the head formation posture was discussed on the basis of hormone balance.
