Abstract: Short daylength is the main environmental factor leading to fall dormancy (FD) in alfalfa (Medicago sativa L.) and also one of the stress factors for alfalfa growth. This research was conducted to explore the effect of the different photoperiods on superoxide dismutase (SOD) and peroxidase (POD) activities in alfalfa varieties with different fall dormancy and the relationship between the antioxidant enzymes and alfalfa fall dormancy. The results show: the SOD and POD activities of the three different fall dormancy varieties, including Vernal (FD=2), CW502 (FD=5), and CUF101 (FD=9), were highest under 8 h day-length, medium under 12 h daylength, and lowest under 16 h day-length, indicating a significant relationship between the SOD & POD activities and photoperiod for alfalfa; the SOD activities of the different fall dormancy alfalfa varieties had no regular change under the same photoperiod, whereas POD activities had the degressive trend with the fall dormancy decreasing; the POD activities of the same variety increased along with the growing season progressed.

Key words: Alfalfa, SOD, POD, Photoperiod, Fall-dormancy

摘要： 短日照是导致苜蓿(Medicago sativa L.)秋眠的主要环境因子,同时也可能是苜蓿生长的一种逆境。本文研究了光周期对不同秋眠型苜蓿超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性的影响,以及两种抗氧化物酶活性与苜蓿秋眠性的关系,为进一步研究秋眠性的生理机制奠定基础。结果表明:无论是秋眠型苜蓿Vernal,半秋眠型苜蓿CW502,还是非秋眠型苜蓿CUF101,其叶片中SOD和POD的活性均呈现出8h光照最高,12h次之,16h最低的趋势,暗示SOD、POD的活性与长日照苜蓿的光周期有关,短日照可提高SOD、POD的活性;在同一光周期下,不同秋眠类型苜蓿品种之间并未在SOD活性上表现出规律性,而POD活性则有随着秋眠性增强而增强的趋势;在同一苜蓿品种中POD活性多随生长期延长而升高。

关键词: 苜蓿, 超氧化物歧化酶, 过氧化物酶, 光周期, 秋眠性