Growth and distribution of non-structural carbohydrates in persimmon seedling trees as affected by different severities of heading-back pruning

摘要

Differences in shoot growth were induced by varying the severity of heading-back pruning in potted 2-year-old trees of persimmon (Diospyros kaki). Four (4-B), eight (8-B) and 12 buds (12-B) were left to investigate shoot growth after the heading-back treatments. Shoot numbers grown from the 4-B, 8-B, and 12-B trees were 3.5, 3.8 and 5.7, respectively. The total shoot length per tree showed no significant difference among the treatments. However, the mean length of 4-B trees was 14 and 55% longer than the 8-B and 12-B trees, respectively. After a season's growth, the dry weight of a shoot from 4-B trees was 10.6 g while that from 12-B trees was 5.2 g. Although leaf numbers per tree were unaffected by the severity of heading-back pruning, the totaland mean leaf areas of 4-B trees were 27% more than those of 12-B trees. Seasonal changes in growth of different parts of the tree were similar among the treatments. A shoot from 4-B and 12-B trees contained 4.53 and 3.27 g of soluble sugars, 2.81 and 1.57 g of starch, respectively. The soluble sugars accounted for 11.1 to 12.3% of shoot dry weight. This proportion appeared to increase with increasing the pruning severity. The amount of non-structural carbohydrates contained in a 1-cm shoot segment wascalculated by dividing the content difference with the mean-length difference between 4-B and 8-B, between 8-B and 12-B, and between 4-B and 12-B trees. Each segment was estimated to contain 31-34 mg of soluble sugars, and 21-29 mg of starch. The pruningseverity did not affect the unit content to a significant level.