Effect Of Nitrogen,Phosphorus And Potassium Fertilizer Rates On Photosynthetic Characteristics And Yield Of Wheat Under Different Soil Moisture Conditions

The experiment was carried out in the experimental farm of Shandong Agricultural University in Tai’an City,Shandong Province in 2018-2019 and 2019-2020.The tested variety was Jimai 22.The experiment adopted a split zone design.The main area was irrigation treatment,and a total of three soil moisture treatments were set up,respectively,W0（no irrigation during the whole growth period）,W1（the relative water content of the soil layer of0～40 cm was supplemented to 70%at jointing and anthesis）,W2（the relative water content of the soil layer of 0～40 cm was supplemented to 90%at jointing and anthesis）.The sub-area was the fertilizer rates treatment,and there were four treatments,namely F0（no fertilization）,F1(N 180 kg·ha^-1,P₂O₅75 kg·ha^-1,K₂O 60 kg·ha^-1),F2(N 225 kg·ha^-1,P₂O₅120 kg·ha^-1,K₂O 105 kg·ha^-1),F3(N 270 kg·ha^-1,P₂O₅165 kg·ha^-1,K₂O 150 kg·ha^-1).A total of 12treatments,and 3 repetitions.To study the effect of nitrogen,phosphorus and potassium fertilizer rates in different soil moisture conditions on photosynthetic characteristics and yield of wheat with a view to provide a basis for high-yield and high-efficiency cultivation of wheat.The results are as follows:Under the same soil moisture conditions,the flag leaf net photosynthetic rate,transpiration rate,stomatal conductance,the actual photochemical efficiency,maximum photochemical efficiency,and photochemical quenching coefficient of F1 treatment were significantly higher than that of F0 treatment.The antioxidant dismutase activity and soluble protein content of flag leaves at flowering stage were significantly higher than those of F0treatment,but were not significantly different from those under F2 and F3 treatments.Under the same fertilizer rates conditions,the photosynthetic parameters,relative chlorophyll content and the chlorophyll fluorescence parameters of W1 treatment were significantly higher than that of W0 treatment,and there was no significant difference between W1 and W2treatment.Under the same soil moisture conditions,leaf area index,photosynthetically active radiation interception rate and interception amount of F1 treatment were significantly higher than F0 treatment.The photosynthetically active radiation transmittance was significantly lower than F0 treatment,Under the same fertilizer rates conditions,leaf area index,photosynthetic active radiation interception and interception rate of W1 treatment were significantly higher than those of W0 treatment.The photosynthetically active radiation transmittance was significantly lower than that of W0 treatment.Under the same soil moisture conditions,the dry matter accumulation at flowering,the distribution amount of dry matter in the vegetative organs at all layers of the plant,the distribution amount in the grains and the total dry matter accumulation at the maturity stage of F1 treatment were significantly higher than that of F0 treatment,but were not significantly different from those under F2 and F3 treatments.Under the same fertilizer rates conditions,the dry matter accumulation at flowering,the distribution amount of dry matter in the vegetative organs at all layers of the plant,the distribution amount in the grains and the total dry matter accumulation at the maturity stage of W1 treatment were significantly higher than that of W0 treatment,and there was no significant difference between W1 and W2 treatment.Under the same soil moisture conditions,the filling rate of F1 treatment and the starch accumulation of grains were significantly higher than that of F0 treatment in the late filling stage.The enzyme activities related to starch synthesis were significantly higher than that of F0 treatment,and there was no significant difference between F1 and F2 and F3 treatments as a whole.Under the same fertilizer rates conditions,the filling rate of W1 treatment was significantly higher than that of W0 treatment in the late filling stage.The starch accumulation of grains and the activities of various starch synthesis-related enzymes were significantly higher than that of W0 treatment,and there was no significant difference between W1 and W2 treatment.Under the same soil moisture conditions,the grain yield and water use efficiency of F1treatment were significantly higher than those of F0 treatment,and nitrogen,phosphorus and potassium fertilizer partial productivity were the highest.Under the same fertilizer rates conditions,the grain yield and nitrogen,phosphorus and potassium fertilizer partial productivity of W1 treatment were significantly higher than that of W0 treatment,and there was no significant difference from W2 treatment.The water use efficiency of W1 treatment was significantly higher than that of W2 treatment.In summary,the F1 treatment(N 180 kg·ha^-1,P₂O₅75 kg·ha^-1.K₂O 60 kg·ha^-1)under the W1（the relative water content of the soil layer of 0-40 cm was supplemented to 70%at jointing and anthesis）moisture condition is the optimal water-saving and fertilizer-saving treatment under the experimental conditions.