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

Abstract

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 CO2 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 oxidative stress which may resulted in female seedlings received less negative effect than male seedlings under salt stress condition.