干旱胁迫下不同地理种源蒙古沙拐枣(Calligomum mongolicum)光合及荧光特性比较

以3个地理种源(武威、张掖、酒泉)蒙古沙拐枣(Calligomum mongolicum)两年生苗木为试材,研究干旱胁迫对其光合及荧光参数的影响,并采用投影寻踪法对其进行了抗旱性评价。结果表明:干旱胁迫导致3个地理种源蒙古沙拐枣光合作用均有所下降,但下降幅度不同,尤其在张掖和酒泉种源间差异显著(p0.05)。在重度干旱时,3个种源的光合速率(Pn)酒泉武威张掖,蒸腾速率(Tr)张掖武威酒泉,气孔导度(Gs)酒泉武威张掖。干旱胁迫下,3个地理种源蒙古沙拐枣的荧光特性表现为初始荧光(Fo)和非光化学淬灭系数(qN)升高,最大光学效率(Fv/Fm)、实际光能转化效率(ФPSⅡ)和光化学淬灭系数(qP)降低。在重度胁迫下,3个种源的Fo和qP大小排序分别为张掖武威酒泉,Fv/Fm、ФPSⅡ和qN为酒泉武威张掖。以投影寻踪法对3个地理种源蒙古沙拐枣的抗旱性排序结果为酒泉武威张掖。

The Responses of Photosynthetic and Chlorophyll Fluorescence to Water Stress in Three Provenances of Calligomum mongolicum

Under different water stress conditions, the changes of photosynthetic and chlorophyll fluorescence characteristics of two years old seedling from three provenances (Wuwei, Zhangye and Jiuquan) of Calligomum mongolicum were determined, and their drought resistances were evaluated with the projection pursuit technique. The results showed that:Water stress decreased the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (Tr), potential efficiency of primary conversion of light energy of PS (F_v/F_m), actual activities of PSⅡ(Ф_PSⅡ) and the photochemical quenching (qP), but increased the minimal fluorescence (F_o) and non-pho tochemical quenching (qN). The changing ranges were different between the three provenances, especially there existed significant differences (p<0.05) between Zhangye and Jiuquan provenances under severe water stress. The value of P_n, G_s, F_v/F_m, Ф_PSⅡ and qN of the three provenances under severe water stress followed an order of Jiuquan>Wuwei >Zhangye; the value of Tr, F_o and qP followed an order of Zhangye >Wuwei>Jiuquan. The modified projection pursuit method was used to study the selection of more drought resistant provenance for C. mongolicum, results showed that the provenance from Jiuquan was the best in drought resistant, followed by that in the provenance from Wuwei, and the provenance from Zhangye was less than the other provenances.