Populus euphratica Oliv. is a typical species for afforestation in xinjiang. Lots of forests have been planted for protecting the ecological environment in south of junggar basin. Yet the survival rate is strained by the scarce water resources. Populus euphratica Oliv. was selected as the reaearch object in this study. The influence of salt water on the physical properties of sand soil and the physiological growth of Populus euphratica Oliv. has been analysed. Under different saline water irrigation condition, we got the salt distribution and accumulation characteristics in sand soil, the relationship between the salt stress and water consumption, chlorophyll, Pro and MDA. Through analyzing the characteristic of salt accumulation in the sand soil and the physiological change of Populus euphratica Oliv. under the salt water irrigation, we got the response characteristic with salt stress. This study can provide scientific basis for making full use of local salty water and improving the survival rate of afforestation. The results show that:
(1)The total salt of sand soil becomes to desalt when the salt content of irrigating water is 1.2-3g/L. The salt in soil increases when the content is 6-12g/L. On the other side, whether the saline or brackish water irrigation, soil salt in 0-200cm shows an increasing trend in the whole growth period. When irrigated using saline water, the accumulation rate of soil salt increases with salinity. There is a direct proportion relationship between the soil salt accumulation and salinity.
(2) Salt water irrigation can make the growth period shorten. The higher the salinity is, the shorter the period is. The Populus euphratica Oliv. does not grow any longer at the end of June when irrigated with salt water of 12 g/L, and the average soil salinity reaches 13.96 g/kg at the same time. When using the salt water of 1.2 g/L, the Populus euphratica Oliv. is growing slowly at the end of August and the average soil salinity is 2.99 g/kg. It has little harm to the growth of Populus euphratica Oliv. under the low salinity level. The relationship of growth and water consumption of Populus emphatics Oliv. can be expressed using the logarithm model. It has a good agreement with the observing results in 1-6 g/L salinity. The relationship is not so strong in 9 g/L, 12 g/L salinity. The minimum of correlation coefficient is 0.7644.
(3) The external form response of Populus euphratica Oliv with salt water irrigation is mainly manifested as growth indices. The inner destruction shows from the typical physiological indexes chlorophyll, proline (Pro) and malondialdehyde (MDA). The three physiological indexes have significant changes under adversity conditions. The leaf chlorophyll content decreases with parabolic, and the Pro and MDA content has a parabolic increasing trend under the salt stress.
The result shows that three kinds of physiological indexes can be used to measure the salt stress level, and short-term salt-water irrigation has little effect on soil safety and the growth of Populus euphratica Oliv.. Salt water is beneficial to reliving ecological water shortage. This study can be a guide to improve the survival rate of afforestation.