Comparisons Of Water Potential Among Populus Euphratica, Haloxylon Ammodendron And Tamarix Ramosissima In Junnger Basin South

Take three desert plants (Populus euphratica, Haloxylon ammodendron and Tamarix ramosissima) as test objects in Corps 150'foison forest', comparing the difference among them and finding the regularity of plant water potential in drought areas. Measured three plants water potential with a dew point of water potential. Combined with the data of their water potential and the ground water level in 2008 and 2009, We analyzed the relationship among their water potentials and the groundwater levels and the air temperature and humidity. Measured three plants water potential with a dew point of water potential, Combined with the data of their water potential and the groundwater level in 2008 and 2009, We analyzed the relationship between their water potentials and the groundwater levels in order to find the response of plant water potential to the groundwater level. The results showed that the diurnal changes of leaf and stem water potential of P. euphratica were "V" type and those of H. ammodendron and T. ramosissima were "W" type. leaf and stem water potentials of natural P. euphratica in 2009 were obviously higher than those in 2008; leaf and stem water potentials of artificial P. euphratica exhibited the same diurnal change trend, that is, which submited the linear type, and were essentially lower than those in 2008; diurnal changes of assimilative shoot water potential of H. ammodendron displayed the same variation trend both in 2008 and 2009, which showed the bimodal pattern; stem water potential of T. ramosissima in 2009 was a little higher than that in 2008, but both diurnal variation are same.Correlation analysis between diurnal variation of leaf and stem water potential of three desert plants and air temperature (humidity) showed that the leaf and stem water potential of artificial old P. euphratica had significant negative correlation with air temperature (the correlation coefficient were -0.839 and -0.818 resprctively); the stem water potential of artificial young P. euphratica had significant negative correlation with air temperature (the correlation coefficient was -0.650); the leaf water potential of artificial young P. euphratica had positive correlation with air humidity, with the coefficient correlation was 0.786; assimilative shoot potential of H. ammodendron had significant negative correlation with air temperature (the correlation coefficient were -0.429), and had positive correlation with air humidity(the correlation coefficient were 0.857); stem potential of T. ramosissima had significant negative correlation with air temperature (the correlation coefficient were -0.893), and had positive correlation with air humidity(the correlation coefficient were 0.571); To sum up, air temperature had a negative impact on water potential of three desert plants while air humidity had a positive one. In the morning, there was significant difference in both leaf and stem water potential of artificial old P. euphratica between 2 m and 5 m or 10 m (P<0.05) and there was no significant difference at 5 m and 10 m (P>0.05); At noon, both leaf and stem water potential at 2 m were significantly different from 5 m and 10 m (P<0.05); At 20:00, water potential of artificial old P. euphratica at different positions all had significant difference (P<0.05). In the morning and afternoon water potential of H. ammodendron of the top was lower than the bottom, in the afternoon water potential of the top was higher than the bottom; at the time point of view, the midday water potential was the lowest. There was significant difference of water potential among morning, noon and afternoon for the top and bottom(P<0.05). Water potential of T. ramosissima was the same as the H. ammodendron at different heights. The results shows that diurnal variation of water potential had significant differences of T. ramosissima and H. ammodendron. Overall, diurnal average variation of water potential of H. ammodendron was lower than T. ramosissima at different heights, which showed that the capacity to resistance to drought.environmental of T. ramosissima was stronger. Differences of water potential of plants at different heights and time was closely related to the height of leaves, different leaf age, physiological functions and the surrounding environmental factors, but moisture is the key factor which restrict their growth.Monthly changes of groundwater depth at 150 group bumper forest from 2008 to 2009 indicated that amplitude was not significant but revealed a downtrend. By comparison, the result of comparison of three plants of water potential is that:Haloxylon ammodendron< Tamarix ramosissima< artificial old P. euphratica. This study has a certain reference meaning to the recovery and recondition and sustainable management of P. euphratica, H.ammodendron and T. ramosissima at bumper forest.