关键词: 紫花苜蓿, 水分胁迫, 生理生化指标, 抗旱性, 水分饱和亏, 甜菜碱, 甜菜碱醛脱氢酶, 脱落酸

Abstract: A study of changes of physiological and biochemical process of drought resistance in 4 alfalfa varieties under different water-stress treatment showed that water saturation deficit, betaine content, betaine aldehyde dehydrogenase activity and abscisic acid content in alfalfa leaves increased notably under water stress. The 4 indexes were evidently different among the 4 alfalfa varieties. Water saturation deficit arose hastily under medium- and severe-stress, compared to control and light-stress-more obvious were WL323 and Queen varieties. With aggravation of water stress, WL323 and Vector alfalfa increased in betaine content, while Queen’s and Aohan’s betaine content inceased initially, then declined. Vector and Aohan were the two varieties having the highest betaine content. Betaine aldehyde dehydrogenase activity in Vector alfalfa increased with the intensity of water stress, while that of the other varieties showed the trend of initial increasing, reaching the peak under medium-stress, then decreasing. Aohan alfalfa’s abscisic acid content changed most obviously under water stress, while that of WL323 changed only slightly. According to correlation analysis, the conclusion was deduced that abscisic acid was indirectly changed the leaves'betaine accumulation through betaine aldehyde dehydrogenase activity under water-stress. The drought resistance capacity of the 4 varieties is sequenced:Aohan alfalfa, ranking the first, followed by Vector and Queen and WL323.

Key words: Alfalfa, Water stress, Physiological and biochemical index, Drought resistance, Water saturation deficit, Betaine, Betaine aldehyde dehydrogenase, Abscisic acid