水分和氮素水平对春小麦光合特性和水分利用的影响

Effects of Water and Nitrogen Levels on Photosynthetic Characteristics and Water Utilization of Spring Wheat

为探明旱作农田不同水肥条件改善作物光合特性和水分利用效率增加作物产量的机理,通过室内盆栽试验,设计40%(W1)、70%(W2)和100%(W3)3个水分梯度以及75 kg/hm2(N1)、225 kg/hm2(N2)2个施氮水平的双因素交互试验,研究水分和氮素水平对春小麦的光合生理、产量和水分利用特性的影响。结果表明:N1W2处理小麦的净光合速率、穗干重、干物质量和水分利用率与高水高氮(N2W3)处理无显著差异;蒸腾速率和气孔导度最高,分别为5.86和157.73 mmol/m2·s,显著高于其他处理;蒸腾量最大,蒸发量最小,蒸腾蒸发比最大,说明水氮合理配施可显著提高小麦的光合特性、水分利用效率和产量。从节水节肥角度考虑,施氮量75 kg/hm2和70%田间持水量耦合可以显著提高小麦的净光合速率和水分利用率,促进灌浆后干物质的积累,增加产量。本试验条件下,N1W2(施氮量75 kg/hm2、70%田间持水量)为最优水氮组合。

In order to explore the mechanism of improving crop photosynthetic characteristics and water use efficiency and increasing crop yield under different water and fertilizer conditions in dry farmland,a laboratory two-factor interaction test experiment was conducted to set three water gradients of 40%(W1),70%(W2) and 100%(W3) and two of nitrogen levels of 75 kg/hm2(N1) and 225 kg/hm2(N2). The effects of water and nitrogen levels on photosynthetic physiology,yield and water use characteristics of spring wheat were studied. The results showed that there was no significant difference between the net photosynthesis rate,ear dry weight,dry matter weight and water use efficiency between N1W2 and high water and high nitrogen treatment N2W3,but the transpiration rate and stomatal conductance were the highest(5.86 mmol/m2·s and 157.73 mmol/m2·s,respectively),which were significantly higher than those of other treatments,and the transpiration was the largest,the evaporation was the smallest,and transpiration/evaporation ratio was the highest. The results indicated that reasonable combined application of water and nitrogen could significantly improve wheat photosynthetic characteristics,water use efficiency and yield. From the perspective of water and fertilizer saving,the coupling of 75 kg/hm2 nitrogen and 70% field water holding capacity could significantly increase the net photosynthetic rate and water use efficiency of wheat,promote dry matter accumulation after grain filling,and increase the yield. Under the experimental conditions,N1W2(nitrogen application rate 75 kg/hm2,70% field water capacity) was the optimal combination of water and nitrogen.