Studies on Photosynthesis and Translocation of Photosynthate in Mulberry Tree : VI. Changes in amylase activity and in amount of carbohydrates in a storage organ after shoot pruning

[摘要] The current year's shoot from the stump of a grafted nursery plant raised in a pot was pruned leaving the basal 3 to 5 cm on July 20. In the process of regrowth after pruning the following items were investigated 8 times for the period July 20 to August 28. They were dry weight of a storage organ formed of a stump and roots, that of newly developed lateral shoots, amylase activity in the bark of a stump, and carbohydrates content in a storage organ. Dry weight of a storage organ declined for a while after pruning, and then turned to an increase on the 20th day after pruning, whereas dry weight of lateral shoots which commenced to develop on the 9th day showed a tendency toward rapid increase on the 15th day (Fig. 1). Amylase activity in the bark of a stump increased to about 150% of the initial level on the 3rd and 6th day, when lateral buds remained dormant visually and then returned to the initial level on the 13th day (Fig. 2). Soluble sugars content in a stump as well as roots showed little change for 9 days after pruning, decreased to a minimum on the 13th day when new shoots began to grow and afterwards turned to an increase (Table 1). Starch content in a stump and roots exhibited remarkable decrease after pruning and turned to an increase after showing a minimum on the 20th to 30th day (Table 2). The amount of sugars in a storage organ decreased to 70% of the initial level on the 13th day, while that of starch less than 20% on the 20th day. In addition, the period required for sugars to turn to an increase was shorter than that required for starch (Fig. 3). From these results, some discussion was given on factors which could affect amylase activity in the bark of a stump after shoot pruning.

[学科分类] 农业科学（综合）