A Study on Relations Between Transpiration of Psammophyte and the Meteorological Components

By means of lysimeter daily transpiration of 7plant species including Elaeagrnus angustifolia, Populus alba var. pyramidalis, and Hedysarum scoparium etc. and transpiration rates of Nitraria tangutorica, Atraphaxis bracteata and Elaeagrnus angustifolia were investigated. The relations between them and meteorological components such as sun radiation, temperature, wind velocity, and relative humidity also were measured. Results show that the daily transpiration of the plants were in the form of parabola, starting at 6:00 am, reaching the peak point at 15:00 pm and then to decline, and coming to the lowest ebb after 24:00 pm. The transpiration (y) was highly correlated with temperature (x 1)(correlation coefficient: 0.861), also correlated with relative air humidity (x 2) and sun radiation (x 3) as well. Among all the components temperature made the largest contribution (contribution rate: more than 51.8%), followed by relative humidity (contribution rate: 27.35%) and sun radiation (contribution rate: 16.14%). Results of the leading factor analysis of each tree species show a high consistency, signifying that all the tree species have the similar responses to the environment. With the increase of ages of the trees, the transpiration rate was falling down. In a growing season, the trees had different transpiration rates in the different months, which means that the transpiration rate is changing with the environmental components. The highest transpiration rate of 3 tree species emerged in June, July and August respectively. The leading elements affecting the transpiration rate were temperature first, then sun radiation, relative humidity and wind velocity as well. Moreover there was a significant linear correlation between the transpiration rate and the age of the trees, sun radiation, and air humidity.