Study Of Water Absorption Of Allium L. And Stipa L.

Two genus , Allium L. and Stipa L., have different water use strategies to adapt themselves to arid environment. In this Master's thesis, the two species of Allium L. and the two species of Stipa L. were chosed to study the drought-resistant characteristics of two genus .The chosed four species are constructive species in desert steppes , with good representation. The drought-resistant characteristics of two genus were studied through irrigating experiment, to determine the water potential, water content, as well as the soil water content and water infiltration . This thesis get the following conclusions:1. A. polyrhizum's water potential is higher than S. klemenzii, and diurnal fluctuation of it is smaller than S. klemenzii. The result showed A. polyrhizum have water-storing ability to adapting to air and soil drought. S. klemenzii is more sensitive to precipitation than A. polyrhizum. It indicated that S. klemenzii's can absorb more water than A. polyrhizum.2. By successive post-drought, the decline of S. klemenzii's water potential is larger than A. polyrhizum, indicating that as a result of A. polyrhizum with water-storing ability, it have relatively stable water potential.3. More than 6mm precipitation is available to A. polyrhizum, while more than 8mm to S. klemenzii. A. polyrhizum's root distribution is more shallow than S. klemenzii ,so it can absorb more water than S. klemenzii, in favor of surviving in the desert steppes.4. After irrigated , the water content of S. klemenzii and A. polyrhizum will increased soon, and then quickly deceased. To determine the water content of the two species, we know that their water contentes increased rapidly in the next day.5. In the experimental plots,after successive post-drought, the soil water content reduce gradually from surface to bottom. 20-30 cm soil layer's water content reduced the maximum, relevant to plant's water absorption .From the surface to 20 cm depth,soil layer water infiltration is the slowest.6. The diurnal variation of water contentes of A. Mongolicum and S. glareosa showed "U" curve change.