Abstract:In order to ascertain the response of photosynthetic parameters of winter wheat during the course of soil water consuming from drought stress to re-watering to different dosage of water-retaining agent and make clear the acting mechanism of water-retaining agent, the pot experiment was employed and water-retaining agent was added to the soil at the following rates: 0 mg/kg, 27 mg/kg, 54 mg/kg, and 81 mg/kg. The results indicated that photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) of wheat were decreased, but water use efficiency (WUE) was increased after the application of water-retaining agent under drought stress. After re-watering, Pn, Tr, and Gs of CK were still higher, and those of water-retaining agent, from high to low, were as the following: 54 mg/kg, 81 mg/kg, 27 mg/kg. When soil moisture content fell to about 55% of field capacity, the photosynthetic parameters of each treatment were ranged in order from the higher to the lower ones as the following: 27 mg/kg, CK, 54 mg/kg, 81 mg/kg. WUE of different treatments were rank as the following: 84 mg/kg, 27 mg/kg, CK, 54 mg/kg. And with the increase of the amount of water-retaining agent, wheat biomass increased, but those of 81 mg/kg of water-retaining agent were significantly high compared with other treatments. Meanwhile, water-retaining agent had an effect on the relations among photosynthetic parameters of winter leaves. The correlations between Gs and Pn and Tr of wheat applied with 54 mg/kg of water-retaining agent were the most closely connected, next were the treatments with 81 mg/kg, CK and 27 mg/kg of water-retaining agent respectively. However, the connections of correlations between Gs and soil, WUE and those between Pn and soil water, Tr, and WUE all showed in the following order: 81 mg/kg, 54 mg/kg,CK, 27 mg/kg. It could be concluded that the treatments with 54 mg/kg and 81 mg/kg of water-retaining agent had significant effect on the correlations between photosynthetic parameters of wheat leaves.
