Effects of soil moisture on photosynthetic characteristics of Larrea tridentata seedlings

In order to find out the ability of drought resistance of Larrea tridentata,the authors used Li-6400 portable photosynthesis system to measure the photosynthetic characteristics,transpiration and stomatal conductance of L.tridentata under different soil moisture treatments.The photosynthetic response curves were measured at the same time.The results showed that,the diurnal curves of net photosynthetic rate and transpiration rate were twin-peaked under better water conditions,and there was a significant midday depression.Under water stress,the average of net photosynthetic rate and transpiration rate depressed distinctly,especially the transpiration rate fell to the extreme low level.It reflected that the ability of reducing the moisture loss of L.tridentatais was strong.With the increase of water stress,photosynthesis was mainly adjusted by stoma,which showed that the ability of adapting the drought with the adjust of stoma of L.tridentata was strong.Light saturation point of L.tridentatais was high,reflecting that L.tridentata belongs to the masculine tree.Water stress had little influence on leaf's actinic process.Photosynthetic apparatus were not harmed by drought.Water utilization efficiency was raised to some extent with water stress.It showed that the ability of drought resistance of L.tridentata was strong.