The Response To Diving Depth Water For Typical Plant’s Water Transport Process In Arid Area

Water is the key factor to plant survival and growth in arid area. Desert plants get water from the soil moisture to maintain normal growth and development. Plant is the key link in SPAC system, and transpiration is the important way for plant to loss water. Based on the theory of thermal diffusion stem flow meter technology, the typical desert plants Haloxylon ammodendron and Tamarisk under different depth groundwater were chose as the study object. Adopting the theory of thermal diffusion stem flow meter technology can study Haloxylon ammodendron and Tamarisk’s water consumption regularity and sap flow correlation with meteorological factors, and it also can study the relationship between photosynthesis, transpiration and environment factors. Under different depth of groundwater some physiological indexes of Haloxylon ammodendron and Tamarisk were measured, and the changes of physiological indexes under drought stress were analysed. The main research results are as follows:(1)Under different depth of groundwater, the start time of Haloxylon ammodendron and Tamarisk’s sap flow is same, Haloxylon ammodendron and Tamarisk’s sap flow rate have obvious diurnal change, and sap flow rate is influenced greatly by solar radiation, temperature and air humidity. When the diving depth of groundwater is 11-13 m, the order for the average value of Haloxylon ammodendron’s sap flow is sunny day before rain > sunny day after rain > rainy day, When the diving depth of groundwater is 15-17 m, the order for the average value of Haloxylon ammodendron’s sap flow is sunny day after rain > sunny day before rain > rainy day,and the value of sap flow rate in sunny day is lager than the value of sap flow rate in rainy day.(2)Under different diving depth of groundwater, the correlation between Haloxylon ammodendron’s sap flow rate and meteorological factors is same. The correlation between total radiation and Haloxylon ammodendron’s sap flow rate is the highest, followed is temperature. Haloxylon ammodendron’s sap flow rate is positively correlated with total radiation and temperature, air humidity is negatively related to Haloxylon ammodendron’s sap flow rate.(3)The diving depth of groundwater is deeper, the value of net photosynthetic rate is smaller, photosynthetic active radiation is the main decision variables of Haloxylon ammodendron and Tamarisk’s net photosynthetic rate in the two test points. The diving depth of groundwater has little effect on Haloxylon ammodendron and Tamarisk’s water use efficiency. When the diving depth of groundwater is 11-13 m, the average value of Haloxylon ammodendron’s water use efficiency is between 1.18 and 1.36, and the average value of Tamarisk’s water use efficiency in the test station is about 1.10; when the diving depth of groundwater is 15-17 m, the average value of Haloxylon ammodendron’s daily water use efficiency is from 1.24 to 1.44, and the average value of Tamarisk’s water use efficiency is between 1.08 and 1.18.(4)Analysis of Haloxylon ammodendron and Tamarisk’s growth indexes during 2013 and 2014, Haloxylon ammodendron has a "summer dormancy" phenomenon after entering August, the diving depthof groundwater is deeper, Haloxylon ammodendron’s summer dormancy is more obvious; after entering July, Tamarisk grows slow or stops the grow, and under different diving depth of groundwater, Tamarisk’s growth is similar. In June Haloxylon ammodendron and Tamarisk’s light energy utilization rate is the maximum, Haloxylon ammodendron and Tamarisk accumulate of a large amount of dry matter.(5)With the diving depth of groundwater is deep, the content of Haloxylon ammodendron’s Proline is high. When the diving depth of groundwater is over 15 m, the accumulation of Tamarisk’s Proline is decrease. When the diving depth of groundwater is over 15 m, the content of Haloxylon ammodendron’s Malondialdehyde(MDA) is decrease, it is the threshold of Haloxylon ammodendron to resist drought stress. With the diving depth of groundwater above 6 m, the accumulation of Tamarisk’s Malondialdehyde(MDA) is decrease, it is the threshold of Tamarisk to resist drought stress.