Effect of High Temperature and Drought Stress on Carbohydrate Translocation in Japanese Apricot ‘Nanko’ Trees

Abstract

With the continuing trend of global warming, the adverse impact of high temperature and the inevitably accompanying drought stress on the growth of Japanese apricot trees (Prunus mume Siebold et Zucc.) are of concern. Therefore, the effects of these factors on photosynthesis and carbohydrate translocation were analyzed. An investigation was conducted at average daytime temperatures of 24°C, 30°C, and 34°C under both irrigated and drought conditions. The 34°C temperature was higher than the open air temperature by 5°C. Stable isotope 13 C was administered to trees to determine carbohydrate positioning. Under the drought stress condition, the photosynthetic rate declined accompanied by temperature elevation, and at the highest temperature of 34°C, 13C concentrations in the twigs and roots were lower than those in the irrigated trees at 24°C. Two-way analysis of variance revealed a trend of 13 C translocation to the young organs above ground, and old organs, while roots were affected by water status, temperature, and their combination, respectively. In the irrigated trees, the photosynthetic rate reduction was not detected, even at higher temperatures. However, translocation incompetence reflecting a decline in 13 C concentration in the roots was observed at 34°C. These results indicate that the permissible diurnal average temperature during summer for the growth of Japanese apricot trees is approximately up to 30°C, and in the temperature range around this irrigation is helpful to facilitate regular functioning of carbohydrate translocation under drought stress conditions.

Effect of Irrigation Amount on Flower Bud Growth and Fruit Set in Japanese Apricot ‘Nanko’

“…1) and 5 mm water treatments, respectively. Tsuchida and Yakushiji (2017) showed that a leaf water potential below −1.5 MPa reduced the rate of photosynthesis. Therefore, apricot trees administered the 10 mm and 5 mm water treatments suffered from severe drought stress and inhibited carbohydrate production during the summer.…”

“…Previous studies have shown that drought stress inhibits stem and root growth (Tsuchida et al, 2011), as well as the allocation of carbohydrates to these organs (Tsuchida and Yakushiji, 2017), in Japanese apricot trees. However, the effects of reduced water supply on the growth of flower buds and fruit yield remain poorly understood.…”