干旱胁迫对麻疯树幼苗光合特性及生长的影响

Effects of Drought Stress on Photosynthetic Characteristic and Growth of Jatropha curcas L.Seedlings

采用盆栽控水的方法,研究了不同程度干旱胁迫对麻疯树幼苗叶片光合特性及植株生长的影响。结果表明:麻疯树幼苗叶片相对含水量(LRWC)、苗高生长量(△H)、地径生长量(△D)、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均随胁迫时间的增加而下降;水分利用效率(WUE)在轻度和中度干旱胁迫下升高,重度干旱胁迫下极显著降低(P<0.01);胞间CO2浓度(Ci)在轻度和中度干旱胁迫下有所降低,重度干旱时极显著上升(P<0.01)。说明在轻度和中度干旱胁迫下麻疯树幼苗光合能力下降的主要原因是气孔限制,而重度干旱胁迫下光合能力下降的主要原因是非气孔限制。在轻度和中度干旱时麻疯树幼苗以降低光合生长和蒸腾耗水、提高水分利用效率来适应环境、维持生命,但长势变弱,而严重干旱时麻疯树幼苗的生长受到土壤水分的严重限制。

Water-controlling pot experiment was carried out to study the effects of drought stress on photosynthetic characteristic and growth of Jatropha curcas L. seedlings. The results showed that leaf relative water content （LRWC）, height growth （△H）, basal diameter growth （△D）, net photosynthetic rate （Pn）, transpiration rate （Tr）, stomatal conductance （Gs） were decreased with the increment of stress time. The water use efficiency （WUE） was increased under mild and moderate drought stress, and dramatically reduced under severe drought stress. The intercellular CO2 concentration （Ci） was decreased under mild and moderate drought stress, and markedly increased under severe drought. This indicated that the decrease of pholosynthetic capacity of J. curcas L. seedling under mild and moderate drought stress is mainly due to stomatal limitation, while that under severe drought stress is mainly due to non stomatal limitation, J. curcas L. seedling could accommodate mild and moderate drought stress environment and sustain life by decreasing Pn and Tr, and increasing WUE, and the growth became weaker on those conditions; however, it could be seriously limited by soil moisture under severe drought stress.