Studies on the Dry Matter Production of Sweet Potato : VI. Varietal differences of respiration and respiration: photosynthesis ratio.

Abstract

An investigation was conducted to determine the changes of respiratory rates in each part of sweet potato and the ratio of nocturnal respiration to photosynthesis per day with four varieties grown under pot cultivation. 1) Leaf blades showed the largest value in the percentage of respiration of each part to total respiration through all the growing stages, i.e. about 50 per cent. of total respiration, and there was no varietal difference in the percentage. At the late growing stage, the respiration of tuberous roots could not show large percentage notwithstanding the ratio of dry-weight of tuber to total dry-weight was large. It was caused by the fact that respiratory rate of tuberous roots was below one-tenth of leaves. 2) The percentage of nocturnal respiration to photosynthesis per day was shown in table 2. After 2nd period (July 13), the percentages showed a static tendency in each variety until harvesting time. Okinawa No. 100 showed low percentage, about 20. Ibaragi No. 1 showed high percentage, about 30. These percentages were obtained under excellent condition of light receiving under pot cultivation. It is assumed that the ratio of respiration to photosynthesis will increase more under inexpedient condition of light for photosynthesis with mutual shading of leaves.