不同水氮管理下玉米叶片衰老对氮转移效率的影响

Effects of Different Water and Nitrogen Managements on Nitrogen Remobilization Efficiency during Leaf Senescence in Maize

为阐明不同水氮管理模式下玉米叶片衰老过程对玉米中氮素转移的影响,进行了大田试验,通过设置3个灌溉水平(150、300、450 m 3/hm^2)和4个施氮水平(0、180、220、260 kg/hm^2),探究不同水氮组合下玉米叶片衰老启动时间、叶片衰老速率、最大绿叶衰减速率出现时间及叶片衰老过程对叶片氮转移效率和籽粒灌浆过程的影响。结果表明:各处理叶片衰老启动时间均发生在吐丝后10 d左右,其受灌水和施氮影响较小;在灌水充足条件下,增加施氮量可以降低叶片衰老速率,延长最大绿叶衰减速率出现时间;施氮量相同时,随灌水量增加吐丝期叶片氮素积累量呈先增加、后减小的趋势;在一定范围内,叶片氮转移效率随最大绿叶衰减速率出现时间的增加而提高,最高可提升25.78个百分点;籽粒灌浆速率呈先慢后快、最后趋于平缓的变化规律,且在吐丝后30~40 d达到最大,延缓叶片衰老速率有助于提高百粒质量;当灌水量为300 m 3/hm^2、施氮量为260 kg/hm^2时,最大绿叶衰减速率出现时间为吐丝后48.90 d,叶片氮转移效率最高,百粒质量最大,是最佳灌水、施氮组合。

Field experiments were conducted to study the effects of different water and nitrogen managements on nitrogen remobilization efficiency during maize leaf senescence process.The experiment included three irrigation levels(150 m^3/hm 2,300 m^3/hm^2 and 450 m^3/hm^2)and four nitrogen application levels(0 kg/hm^2,180 kg/hm^2,220 kg/hm^2 and 260 kg/hm^2).The date of onset of leaf senescence,maximum rate of decrease in relative green leaf area,mean rate of decrease in relative green leaf area and the day of maximum rate of decrease in relative green leaf area under different water and nitrogen conditions were analyzed.The effects of nitrogen remobilization efficiency and grain filling process during leaf senescence process were also studied.The results showed that the date of onset of leaf senescence under each treatment occurred about 10 days after silking,and it was less affected by irrigation and nitrogen application.Under sufficient irrigation conditions,increasing nitrogen application could reduce maximum rate of decrease in relative green leaf area and prolong the day of maximum rate of decrease in relative green leaf area.With the same amount of nitrogen application,leaf nitrogen accumulation was increased first and then decreased with the increase of irrigation at silking stage.Within a certain range,leaf nitrogen remobilization efficiency was increased with the continuous increase of the day of maximum rate of decrease in relative green leaf area,and the maximum increment was 25.78 percentage points.The grain filling rate was slow first,and then fast,and eventually tended to change smoothly.The grain filling rate reached the maximum value after 30~40 days of silking.Delaying leaf senescence rate was helpful to improve 100-grain quality.When the amount of irrigation was 300 m 3/hm^2 and the nitrogen amount applied was 260 kg/hm^2,the day of maximum rate of decrease in relative green leaf area occurred at 48.90 days after silking and both leaf nitrogen remobilization efficiency and 100-grain quality were the highest.