喷灌与地面灌溉条件下冬小麦光合作用的日变化研究

Diurnal changes of photosynthesis of winter wheat under sprinkler irrigation and surface irrigation conditions

为比较不同灌溉方式下作物光合作用日变化的差异,该试验选择晴朗天气,采用LI-6400便携式光合作用仪观测了喷灌和地面灌溉条件下冬小麦灌浆期光合作用参数的日变化.试验结果表明:与地面灌溉条件下相比,喷灌条件下冬小麦旗叶的净光合速率增加,细胞间隙CO2浓度减小,蒸腾速率和气孔导度除在光合'午休'期间(12:00～14:00)较大外,在其它时段均低于地面灌溉条件下;喷灌和地面灌溉条件下冬小麦的光合'午休'均是'气孔限制'与'非气孔限制'共同作用的结果,但在喷灌条件下,光合'午休'主要由气孔限制引起的,而在地面灌溉条件下,光合'午休'主要由叶肉细胞光合活性下降导致的非气孔限制引起的.试验结果表明喷灌可以改善叶肉细胞的光合能力,使光合'午休'期间阻碍光合速率进一步提高的主要因素由非气孔限制逐渐转变为气孔限制.

Diurnal changes of photosynthesis of winter wheat during grain filling stage under sprinkler and surface irrigation conditions were studied in sunny clays to investigate the differences among photosynthesis features of different irrigation methods. Photosynthesis features including net photosynthesis rate, transpiration rate, stomatal conductance, intercellular CO2 concentration of winter wheat flag leaves were measured using a portable LI-6400 photosynthesis system under sprinkler and surface irrigation conditions. The results were as follows. compared with that under surface irrigation condition, the net photosynthesis rate of winter wheat flag leaves under sprinkler irrigation was increased, and the intercellular CO2 concentration was reduced. The transpiration rate and stomatal conductance of winter wheat flag leaf under sprinkler irrigation condition were higher than those under surface irrigation condition at photosynthetic midday depression time, but were lower at other diurnal time （12 ： 00-14 ：00）. The photosynthetic midday depression under sprinkler and surface irrigation conditions was resulted from the stomatal limitation factor and nonstomatal limitation factor. Under sprinkler irrigation condition, it was predominantly due to the stomatal limitation factor caused by decreased photosynthetic capacity of mesophyll cells, while it was predominantly due to stomatal limitation under surface irrigation condition. The results indicated that the photosynthesis activity of mesophyll ceils in winter wheat flag leaves under sprinkler irrigation was improved, which made the limiting factor of photosynthesis rate change from nonstomatal limitation to stomatal limitation gradually.