Isotope Tracer Technique·Ecology and Environment·Physiology
HOU Liyuan, CHEN Yuhuai, WANG Yuchuan, HONG Danxia, WANG Yixue, CHEN Zhe, WU Shenjie, DONG Yanhui
To study the dynamics of physiological responses of quinoa (Chenopodium quinoa Willd.) to continuous drought stress, three cultivars of quinoa, JinLi1 (JL1), JinLi2 (JL2) and JinLi3 (JL3), were used to identify drought tolerance at seedling stage under the drought stress of 20 % polyethylene glycol (PEG) 6 000 solution. After 0, 0.5, 2, 8, 24, 48 and 72 hours of continuous drought stress, the physiological and biochemical indexes were measured to evaluate the drought tolerance, screened the identification indexes of quinoa and comprehensively evaluated quinoas at seedling stage. The results showed that with the extension of drought stress time, the leaf relative water content (RWC) was decreased gradually, the contents of malonic dialdehyde (MDA) and soluble sugar (SS) were increased, and the activities of antioxidant enzymes were increased first and then decreased; the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) peaked at 24 h, peroxidase (POD) activity reached the maximum at 48h; the contents of proline (Pro) and soluble protein (SP), the productive rate of superoxide anion () on each varieties were different; the Pro contents of JL1 and JL2 were increased with the extension of stress time, the Pro content of JL3 was increased first and then decreased, reached the maximum at 48 h; the SP content of JL1 was decreased first, then increased and then decreased, the soluble protein contents of JL2 and JL3 were increased first and then decreased; the production rates of JL1 and JL3 showed continuous rise, JL2 increased first and then decreased. These results suggested that the effect of drought stress duration on each index was different and most of the indexes changed greatly at 24 h and 48 h. In addition, the physiological index had a certain threshold responses to drought stress. Both principal component analysis and membership function analysis showed that the drought tolerance of the tested quinoa germplasm was JL1 > JL2 > JL3. This study results provide theoretical basis for the study of drought tolerance mechanism and breeding of new drought-tolerant varieties.