Effects of Water and Fertilizer Coupling on Photosynthetic Characteristics in Flag Leaves and Yield of Winter Wheat under High Yield Condition

Water and fertilizer are key factors affecting the growth and development of wheat.A field experiment was carried out to study the effects of different water and fertilizer coupling on photosynthetic characteristics of flag leaves and grain yield under high yield condition in Huang-huai plain.The results indicated that the different modes of water and fertilizer coupling had different influences on the photosynthetic characteristics of flag leaves and grain yield,and the overall performance of the soil moisture treatment was greater than that of the nitrogen application.The photosynthetic rate of flag leaves(Pn) and stomatal conductance of flag leaves(Gs) were significantly increased with increasing of soil moisture and the order was that W3(plenty of water) W2(suitability moisture) W1(natural rainfall),while intercellular CO2 concentration of flag leaves(Ci) reduced with increasing of soil moisture.When applied to different nitrogen treatments,flag leaf Pn)and Gs increased with the increase of the amount of nitrogen and showed as N3(270 kg·hm-2) N2(195 kg·hm-2) N1(CK),while Ci in different amounts of nitrogen shares no similarity with different water conditions.However,different water and fertilizer coupling mode of water use efficiency showed as W2 W3 W1,and W2N2 was demonstrated the best treatment combinations whether in water use efficiency or grain yield.All of this indicates that W2N2 may be the high yield and high efficiency model under high yield condition.