银杏幼苗雌雄株对盐胁迫响应的差别

采用对盆栽银杏(Ginkgo biloba)雌雄幼苗浇灌NaCl(40?mmol L-1)溶液模拟土壤受盐胁迫的方法,研究银杏雌雄幼苗气体交换特征、内在水分利用效率(WUE)、游离脯氨酸含量(Pro)、超氧化物歧化酶(SOD)及过氧化物酶(POD)活性在盐胁迫下的差异.结果表明:(1)盐胁迫后雌株的净光合速率、气孔导度以及蒸腾速率与对照相比分别降低45.87%、25.00%、16.47%,而雄株的气孔导度、胞间CO2浓度和蒸腾速率分别升高了10.00%、8.10%、22.95%;(2)盐胁迫显著降低了银杏幼苗的WUE(P=0.020),与对照下相比,雌、雄WUE分别下降30.47%、46.38%;(3)盐胁迫显著提高了雄株的游离Pro含量,但对雌株影响不显著;(4)盐胁迫使银杏雌、雄幼苗SOD活性分别降低了22.96%、23.18%,但下降幅度均不显著.然而盐胁迫会显著降低雌株的POD活性,但对雄株无显著影响.上述结果同时表明,40?mmol L-1的NaCl溶液不仅会降低银杏雌雄幼苗的光合速率,影响气体交换,还会降低WUE、SOD及POD等酶活性,提高游离Pro含量,但雌株受到的负面效应小于雄株.与雄株相比,雌株在盐胁迫下能通过维持较高的光合速率贮藏能量,较低的蒸腾速率和较高的内在水分利用效率以减少水分散失,以及较高的抗氧化物酶活性来缓解盐胁迫带来的氧化胁迫,使其受到的负面影响减小.

Different Physiological Responses of Male and Female Ginkgo biloba (Ginkgoaceae) Seedlings to Salt Stress

In the present study, male and female Ginkgo biloba seedlings were used to examine changes in gas exchange, the intrinsic water use efficiency (WUE), free proline (Pro) content, peroxidase (POD) and superoxide dismutase (SOD) activity under the condition of adding 40 mmol L~(-1) NaCl solution into the soil monitoring the soil under the salt-stress. The results showed that the net photosynthetic rate, stomatal conductance and transpiration rate in salt-stressed female G. Biloba seedlings decreased 45.87%, 25.00%, 16.47% respectively, while the stomatal conductance, intercellular CO_2 concentration, and transpiration rate in salt-stressed male seedlings increased 10.00% , 8.10%, 22.95%, respectively comparing with control; Significantly, lower levels of the WUE were observed in both salt treated female and male seedlings which decreased ( P = 0.020), 30.47% and 46.38% respectively. Salt-stressed male seedlings were found higher level of free Pro content while no significant change were found in the same treated female seedlings. The SOD activities in both treated seedlings decreased 22.96% and 23.18% respectively without significant variations. Furthermore, the activities of POD in salt treated female seedlings decreased significantly, while that of the male showed no significant change at all. It was indicated that under 40 mmol L~(-1) NaCl salt stress treatment female seedlings maintained higher photosynthetic rate to accumulate energy, lower transpiration rate and higher intrinsic water use efficiency to reduce disperse of water content, and higher antioxidant enzyme activities to relieve oxidstive stress which may resulted in female seedlings received less negative effect than male seedlings under salt stress condition.