The Variation Of Luxury Transpiration And Its Regulation In Winter Wheat

In this paper,we adjusted different shade levels beyond the point of light saturation and water coupling model to study the regulation of photosynthetic active radiation and moisture on winter wheat photosynthetic characteristics,yield and water use efficiency etc.We explored not only to maintain or enhance the yield and water use efficiency of winter wheat,but also reduced ineffective water consumption.Four shading treatments(S0: 0% shading;S1:10-20% shading;S2: 30-40% shading;S3: 50-60% shading)and two watering treatments(high water: full irrigation;low water: deficit irrigation)were established for field experiment.The main research results are as follows:(1)By analyzing the photosynthetic rate and transpiration rate of winter wheat in two wheat seasons,we found that the luxury transpiration existed in winter wheat after jointing stage,and the luxury transpiration of winter wheat was quantified by calculation.After analysis,it was found that the luxury transpiration of winter wheat increased with the increasing growth period,but it decreased after the filling stage,and it was noted that the luxury transpiration was sensitive to water.(2)In the shading condition,compared with S0 treatment,photosynthetic rate of S1 treatment showed a downtrend,which was statistically non-significant,while transpiration rate decreased significantly in high water treatment.It can be regarded as an effective measure to restrain luxury transpiration.Compared with S0 treatment,photosynthetic rate and transpiration rate of S2 and S3 treatments were significantly reduced.Under low water treatment,compared with S0 treatment,photosynthetic rate of S1,S2 and S3 treatments decreased significantly.The transpiration rate of S1 treatment was significantly lessen,the transpiration rate of S2 and S3 treatments had a downtrend but was not significantly compared with S0 treatment.Therefore,shading treatment under low water treatment is not an ideal way to restrain luxury transpiration.(3)Shading and watering treatments had significant effects on avarage value of canopy photosynthetic rate and canopy transpiration rate of winter wheat in all growth periods.Under the condition of high water treatment,compared with S0 treatment,the diurnal canopy photosynthetic rate of S1 treatment did not decrease significantly,but the diurnal canopy transpiration rate decreased significantly.However,S2 and S3 treatments significantly reduced diurnal canopy photosynthetic rate and diurnal canopy transpiration.Under the condition of low water treatment,shading and water treatments had little effects on canopy photosynthetic rate and canopy transpiration rate.(4)Shading and watering treatments had significant effects on the yield,water consumption and water use efficiency of winter wheat.Under the condition of high water treatment,compared with S0 treatment,S1 treatment did not significantly reduce the yield of winter wheat,but reduced the water consumption and improved water use efficiency,it is a water-light combination measure which can not only ensure the yield but also save water.S2 and S3 treatments significantly reduced water consumption and yield of winter wheat,and also significantly reduced water use efficiency.Under the condition of low water treatment,the yield,water consumption and water use efficiency of S1,S2 and S3 treatments were not statistically different from S0 treatment.