Protective enzyme activity and physiological properties of four mulberry varieties affected by drought stress in the Panxi Region of Sichuan Province, China

Abstract

In order to identify the effects of drought stress on protective enzyme activity and physiological properties, four mulberry varieties, i.e.,‘Nanye-1’, ‘Yunsang-1’, ‘Xinyizhilai’ and ‘Husang-32’ in the Panxi Region of Sichuan Province, China, were selected. The activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in four mulberry varieties was determined. Soluble protein, soluble sugar, proline, net photosynthetic rate and transpiration rate of mulberry leaves were analyzed. The results show that during the early stages of drought stress, protective enzyme activities in four mulberry varieties continually increased. However, prolonged and intensified drought stress decreased their activities. After re-watering, they gradually returned to normal levels. Under drought stress and after re-watering, ‘Nanye-1’ and ‘Yunsang-1’ clearly showed smaller changes in soluble protein content than the ‘Xinyizhilai’ and ‘Husang-32’ varieties, whereas changes in their soluble sugar content were clearly greater than these last two varieties. When water deficit was protracted and intensified, ‘Nanye-1’ and ‘Yunsang-1’ still showed higher net photosynthetic, transpiration rates and water-use efficiency than ‘Xinyizhilai’ and ‘Husang-32’.