不同氮肥模式对夏玉米冠层结构及部分生理和农艺性状的影响

Effects of Different Nitrogen Regimes on Canopy Structure and Partial Physiological and Agronomic Traits in Summer Maize

以郑单958为试验材料,设基肥低氮、基肥高氮、第1次氮肥在拔节期施入和不施氮4个处理,研究了施氮模式对冠层结构及部分生理和农艺性状的影响。结果显示,施氮处理各指标均优于不施氮处理。适当减少基肥氮量,具有以下优势:(1)在保证苗期氮肥供给的同时,每公顷节肥90kg;(2)改善了冠层结构,增加了群体底层的透光率,使穗上叶和整株的茎叶夹角更紧凑,与基肥高氮处理相比分别减少4.33°和4.67°,同时降低了株高和穗位高,缩短了基部节间长度,有效防止茎秆倒伏;(3)与前期高氮处理相比,基肥低氮在灌浆初期叶片的叶绿素相对值和全氮含量均处于较高水平;(4)基肥低氮处理提高了单位面积的株数,并减少了秃尖长度,同时千粒重和穗粒数有所增加,最终获得较高产量。第1次氮肥在拔节期施入,前期控氮时间过长,营养元素失衡,苗期发育不良,不利于产量形成。

Over-fertilized nitrogen leds to irrational crop canopy in summer maize,and thus negatively affected yield production.Therefore,it is important to study the nitrogen application time and level for the construction of efficient crop canopy.A field experiment was conducted using summer maize Zhengdan 958 with four nitrogen application regimes including low basal nitro-gen fertilizer（30 kg ha-1）,high basal nitrogen fertilizer（120 kg ha-1）,first nitrogen dressing at jointing stage（30 kg ha-1）,and zero-nitrogen.The results showed that canopy structure and other indexes were improved by nitrogen input.Slightly reducing of basal nitrogen provided the following advantages：（1） The amount of nitrogen fertilizer was significantly reduced without negative effect to maize seedlings,i.e.90 kg ha-1 nitrogen saved;（2） The canopy structure was improved with high light transmission rate at the bottom of canopy and more compact leaf structure.Compared with the treatment of high basal nitrogen fertilizer,the leaf angel above ear of canopy and mean leaf angel decreased 4.33° and 4.67° respectively in the treatment of low basal nitrogen fer-tilizer.Simultaneously,plant height and ear height were both reduced and the length of the basal stem internodes shortened,which effectively prevented stem from lodging;（3） Under low basal nitrogen fertilizer,canopy SPAD value and nitrogen concentration of the leaf were equivalent with high basal nitrogen treatment;（4） The grain yield was higher under low basal nitrogen fertilizer than under other nitrogen regimes due to the increase of ear number,thousand grain weight,grain number per ear and the decrease of bald tip length of the ear.First nitrogen dressing at jointing stage led to worse nitrogen condition before jointing stage,and thus limited yield formation and crop growth due to runtish seedlings and imbalanced nutrition.