Abstract:

To explore the adaptability of the dominant desert plant Haloxylon ammodendron to salt water irrigation at different high salinity （10， 20， 30， 40， 50 g·L^-1） The response and adaptation of growth， chlorophyll content， osmotic regulatory substance content， antioxidant enzyme activity， respiration and chlorophyll fluorescence index of the aboveground part of the plant were systematically analyzed. The results show that： at first， with the increase of the salinity of irrigation water （up to 20 g·L^-1）， the soil diameter and new shoots were significantly inhibited， and the plants continued to grow at 50 g·L^-1，showing strong salt tolerance. Next， the content of osmotic regulating substances and antioxidant enzyme activity increased at low concentration， but decreased when the salinity of irrigation water exceeded 20 g·L^-1. At the same time， the main factors limiting the net photosynthetic rate of assimilative shoot gradually changed from nonstomatal limitation to stomatal limitation with the increase of irrigation time， and the differences among groups decreased. In the end， the quantum efficiency of assimilation branch photochemistry decreased significantly with the increase of irrigation water salinity， and there were significant differences between groups 40 g·L^-1 and 50 g·L^-1 and the control group， and the decrease of each treatment decreased after 60 d of irrigation.

Key words: Haloxylon ammodendron, salt water irrigation, gas exchange, chlorophyll, fluorescence