施氮量对不同土壤肥力条件下冬小麦光合特性和产量的影响

为给"小麦-玉米"轮作体系下不同土壤肥力麦田的小麦施氮量提供参考,选择开封八里湾(土壤肥力水平高)、郑州(土壤肥力水平中等)和开封水稻乡(土壤肥力水平低)为试验地点,3个试验地点均设置4个施氮水平(即小麦季0、180、240和300 kg·hm~(-2);玉米季0、225、300和375kg·hm~(-2)),研究不同施氮量对小麦光合特性及产量的影响。结果表明,施氮处理增加了冬小麦的光合速率、叶绿素含量、全氮含量和Rubisco活性,与不施氮处理相比,分别增加22.4%～183.3%、37.9%～306.2%、49.6%～359.3%和27.4%～59.5%;不同肥力试点施氮后,产量增加幅度不同,与N0施氮水平相比,高肥力试点各施氮水平处理增产幅度为10.8%～54.9%,中肥力试点为125.3%～165.8%,低肥力试点为63.3%～288.2%;在定位试验进行3年后,高、中、低肥力试点在4个施氮处理下的平均产量分别提高36.1%(2014-2015年度)、136.4%(2014-2015年度)和288.2%(2016-2017年度),表明施氮增产效应与土壤肥力密切相关,高肥力麦田土壤基础肥力高,土壤贡献产量大,对氮肥依赖性低,施氮增产效果不明显。从产量构成因素看,产量由低产到中高产水平主要依靠穗数增加,由中高产到高产水平主要依靠穗粒数增加。因此,为充分发挥氮肥的增产效应,在低肥力麦田,应少量多次施氮;在中肥力麦田,应提倡稳氮,以促穗数为主,施氮量为240kg·hm~(-2);在高肥力麦田,应注意控氮,以增粒为主,施氮量为180 kg·hm~(-2)。

Effect of Nitrogen Application Rates on Photosynthetic Characteristics and Yield of Winter Wheat under Different Soil Fertility Conditions

In order to provide the information for N application in the wheat-maize rotation system under different soil fertility conditions,we selected the Kaifeng Baliwan(high soil fertility level),Zhengzhou(medium soil fertility level) and Kaifeng Shuidaoxiang(low soil fertility level) as the experimental sites to investigate the effect of nitrogen(N) application rates on photosynthetic characteristics and yield of winter wheat.Four different N fertilizer rates were used in the field experiments(wheat growing season:0,180,240 and 300 kg·hm^-2;maize growing season:0,225,300 and 375 kg·hm^-2,respectively) at the three sites.The results indicated that N application significantly increased photosynthetic rate,chlorophyll content,total N content and Rubisco activity by 22.4%-183.3%,37.9%- 306.2%,49.6%-359.3% and 27.4%-59.5%(average value of N180,N240 and N300) compared to non-N application,respectively. The increase rates of yield were different after N application at three fertility levels,10.8%-54.9% for high fertility soil, 125.3%-165.8% for medium fertility soil,and 63.3%-288.2% for low fertility soil compared to that under N0 treatment. When the experimental progressed three years,the wheat yield was increased by 36.1%(2014-2015),136.4%(2014-2015) and 288.2%(2016-2017) in high,medium and low fertility soil under the N treatments compared to that under N0 treatment,respectively. This suggests that the effect of N application on wheat depended on soil fertility. In high fertility wheat field,the basic soil fertility is high,and the contribution of soil to yield is large,but the dependence on nitrogen fertilizer is low,and thus the effect of nitrogen application on yield increase is not obvious. From the perspective of yield components,the yield from low yield to medium yield mainly depends on the increase of panicle number,and from medium yield to high yield mainly depends on the increase of grain number per panicle. Therefore,in order to get full effect of N fertilizer on yield increase,in low fertility wheat field,a small amount of nitrogen should be applied several times; in medium fertility wheat field,nitrogen should be stabilized,mainly to promote panicle number,with nitrogen application rate of 240 kg·hm^-2; in high fertility wheat field,attention should be paid to nitrogen control,mainly to increase grain,with nitrogen application rate of 180 kg·hm^-2.