不同土壤水分条件下中国沙棘雌雄株光合作用、蒸腾作用及水分利用效率特征

采用LI-6400便携式光合系统对野外不同生境(沟底、坡面)和田间不同土壤水分条件下中国沙棘雌雄株的净光合速率和蒸腾速率及水分利用效率特征进行了观测,结果表明,中国沙棘雌雄株在水分条件较好的生境中均表现较强的生活力,净光合速率和蒸腾速率主要受光照强度和大气温度的影响,雄株表现出更高的光合、蒸腾、水分利用效率;在水分条件较差的生境中,雌雄株均通过降低蒸腾和提高水分利用效率来适应逆境,净光合速率和蒸腾速率的影响因子增多,雄株的光合速率大幅度下降,雌株仍保持较高的光合速率,雌株的水分利用效率高于雄株.可见,在反映植物瞬时生理变化的性状方面,雌株对土壤水分减少表现出了更强的适应性,雄株对土壤水分变化表现出了更大的敏感性.

Effects of soil moisture levels on photosynthesis, transpiration, and moisture use efficiency of female and male plants of Hippophae rhamnoides ssp. Sinensis

Net photosynthesis and transpiration rates of female and male individuals of Hippophae rhamnoides ssp. sinensis were measured under different soil moisture conditions using the LI-6400 portable photosynthesis system. We studied two habitats corresponding to high (gully) and low (slope) soil moisture. We also applied four levels of soil moisture to plants grown in our experimental farm. The results showed that H. rhamnoides ssp. sinensis performed better under higher soil moisture conditions. Net photosynthesis and transpiration rates were mainly affected by photosynthetically active radiation (PAR) and air temperature (TA). Male plants were characterized by higher photosynthesis and transpiration rates and higher moisture use efficiency. When soil conditions were drier, female and male individuals adapted by reducing transpiration and increasing moisture use efficiency. During these periods more factors affected Net photosynthetic and transpiration rates. Photosynthetic rate of male individuals decreased greatly, whereas female plants maintained higher photosynthetic rate and exhibited higher moisture use efficiency. We conclude that female individuals of H. rhamnoides ssp. sinensis are more adaptable to lower soil moisture. In contrast, male plants are much more sensitive to changes in soil moisture.