Author(s): Pengcheng Tang; Bing Xu; Kezhen Guo; Xiaoyu Gao
Linked Author(s): Bing Xu
Keywords: Tibet; Alpine pastoral area; Oat; Physiological indicator; Meteorological factor
Abstract: The meteorological characteristics are high temperature difference, strong solar radiation and significant change of air humidity in the alpine area of Tibet. According to these features, the field experiment was conducted to analyze the diurnal variation of the leaf water potential (ψL), stomatal conductance (Gs), transpiration rate (E) and net photosynthetic rate (Pn). Meanwhile, the relationship between typical meteorological factors such as atmospheric temperature (T), solar radiation (Rs), relative air humidity (RH) with oat's physiological indicators were investigated with the corresponding regression models. The experiment results show that the daily oat’s ψL changed obviously during the different growth stages. The daily oat’s change curve ψL show ‘V-type’ in the seeding and heading stages, and the lowest value respectively appeared in 5: 00 a. m and 4: 00 p. m. However, oat’s ψL show ‘W-type’ in the jointing and tillering stages in which the lowest value both appeared in the morning and afternoon. The maximum change range of ψL can reach 6 MPa in a day. At the same time, the diurnal variation of Gs, E and Pn respectively show ‘bimodal’, ‘multimodal’, ‘bimodal’. In detail, the maximum value respectively were 6. 495 millimol•m-2s-1, 42. 31 millimol•m-2s-1, 66. 46μmolm-2s-1 which appeared in 9: 00 a. m, 4: 00 p. m, 12: 00 a. m. Based on the regression analysis, the effect order of meteorologic factors on oat's four physiological indicators are: T>RH>Rs; Rs>RH>T; RH>Rs>T; T>RH>Rs, respectively for ψL, Gs, E and Pn. These results are useful to understand the hydrologic cycle of the irrigated grass, and determine the scientific irrigation schedule with improve water use efficiency of grass in the alpine area.