Effects Of Nitrogen Application Rate On Root Growth And Photosynthetic Matter Production Of Winter Wheat Under Drip Irrigation

To reveal the effect of nitrogen application on growth of root and yield of winter wheat under drip irrigation. There were five different nitrogen application treatments, which were N0（0kg·hm-2）,N1（90kg·hm-2）,N2（180kg·hm-2）,N3（270kg·hm-2）,N4（360kg·hm-2）,the objective of this study was to explain the effects of nitrogen application rate on photosynthetic characteristics of flag leaves and root length, root weight, root volume, root activity, root surface area in 0⁶0 cm soil layer, and accumulation and distribution of dry matter and nitrogen in different organs of wheat plant,The results showed that:（1） With the increase of amount of nitrogen fertilizer, root dry weight, root length and root activity increased during the jointing and maturity in 0-60 cm soil layer,, root dry weight, root length of N3 than N0 increased 11.93%, 29.0% at booting stage in 0-60 cm soil layer, an increase of basic performance for 0²0 cm>20⁴0 cm > 40⁶0 cm soil layer;wheat yield of N3 than N0 treatment increased 30.35%, reduce agronomic N use efficiency, by 12.07 kg·kg^-1（N1） decreased 6.90 kg·kg^-1（N3）.（2） In 0²70 kg·hm-2 applied range of nitrogen, a significant increase in light of wheat canopy leaf area index, flag leaf photosynthetic rate, chlorophyll content, chlorophyll a content, chlorophyll b content, soluble protein content, stomatal conductance, intercellular CO2 concentration decreased, a significant improvement in the flag leaf photosynthetic characteristics, nitrogen application amount is greater than 0²70 kg·hm-2 and total chlorophyll, chlorophyll a, chlorophyll b content increase was not significant.（3） Nitrogen fertilizer increased dry matter accumulation, compared with N0, N4 dry matter accumulation increased 39.12%, distribution scale showed a downward trend; agronomic nitrogen use efficiency, nitrogen uptake efficiency, nitrogen partial productivity decline, nitrogen harvest index in N3 treatment reaches the maximum value decreased after 0.77 and N3, N4, an increasing trend was not significant.（4） Jointing stage to booting stage application amount of nitrogen fertilizer enhances in 0-60 cm soil layer, root growth and activity, increase leaf area index of population, improve photosynthetic rate of flag leaf, increase during the jointing and maturity of dry matter accumulation is the important reasons of the increase of nitrogen application.（5） Under this experiment conditions, the optimum amount of nitrogen was 180²70 kg·hm-2,obtained yield 7591.49⁸004.85 kg·hm-2, AEN was 6.9⁸.06 kg·kg^-1,Optimum nitrogen application rate of yield and nitrogen use efficiency.