氮肥后移对绿洲灌区玉米干物质积累和产量构成的调控效应

【目的】针对绿洲灌区传统施氮技术下,全膜覆盖玉米生育后期土壤氮肥供应不足、早衰和减产等问题,探讨氮肥后移对玉米干物质积累和产量构成的影响,以期为优化试区氮肥管理提供理论依据。【方法】2012—2015年,于河西绿洲灌区进行大田试验,在总施氮量相同且基肥和大喇叭口期追肥分别占总施氮量20%和40%条件下,设3个施氮处理:氮肥后移20%(拔节肥10%+花粒肥30%,M1)、氮肥后移10%(拔节肥20%+花粒肥20%,M2)和传统施氮(拔节肥30%+花粒肥10%,M3),研究不同氮肥追施制度对玉米干物质积累动态和产量构成的调控效应。【结果】氮肥后移增大了玉米干物质最大增长速率和干物质平均增长速率,提前了干物质最大增长速度出现的天数。在氮肥后移20%施氮制度下,玉米干物质最大增长速率和干物质平均增长速率分别较传统施氮处理提高15.6%和6.6%,玉米干物质最大增长速率出现的天数较传统施氮提前2.9 d。施氮制度对玉米生物产量、籽粒产量、收获指数、有效穗数、穗粒数和千粒重均有显著影响。氮肥后移20%施氮制度下,玉米生物产量较传统施氮处理高6.6%,但氮肥后移10%处理生物产量与传统施氮处理差异不显著;氮肥后移20%和10%处理玉米的籽粒产量分别较传统施氮处理提高14.1%和5.1%;氮肥后移20%施氮处理收获指数较传统施氮处理高7.5%,但氮肥后移10%施氮处理与传统施氮处理差异不显著;氮肥后移20%施氮处理下,玉米有效穗数、穗粒数和千粒重分别较传统施氮处理高8.9%、12.9%、5.8%,但氮肥后移10%处理的千粒重与传统施氮处理差异不显著。通径分析表明,氮肥后移主要通过提高有效穗数,进一步提高穗粒数和千粒重,从而提高产量。说明氮肥后移20%施氮处理通过优化玉米有效穗数、穗粒数和千粒重对产量产生了调控作用。【结论】在河西绿洲灌区,总施氮量450 kg·hm~(-2)时,玉米拔节期追肥45 kg·hm~(-2)、大喇叭口期追肥180 kg·hm~(-2)、花后10 d追肥135 kg·hm~(-2)为该区获得玉米高产的理想施氮制度。

Response of Dry Matter Accumulation and Yield Components of Maize Under N-Fertilizer Postponing Application in Oasis Irrigation Areas

【Objective】In oasis irrigation agricultural region, the traditional fertilizer application in maize production has caused serious problems, such as soil available nitrogen hunger, premature-senescence and yield reduction in the late growth stages under plastic-film mulching. The aim of this study was to provide academic and practical evidence for enhancing dry matter accumulation and yield parameters of maize through the optimization of nitrogen fertilizer management. 【Method】The three-year field experiment was carried out in Hexi Oasis irrigation region of Gansu province from 2012 to 2015. Each of the treatment in this study received the same amount of total nitrogen and with 10% as basal N and 40% as pre-tasseling N. Three N application treatments were set with application of different N amounts postponed from jointing N to post-flowering N: 20% of N postponing applied (M₁), 10% of N postponing applied (M₂), and traditional nitrogen application (M₃). 【Result】Postponing of application of nitrogen fertilizer increased the highest dry matter accumulation rate, the average dry matter accumulation rate and advanced the days of emergence of the highest dry matter accumulation rate. Compared with traditional nitrogen application, the maximum dry matter accumulation rate and the average rate of maize in the treatment with postponing application of 20% of N was increased by 15.6% and 6.6%, respectively. Meanwhile, the days of emergence of the highest dry matter accumulation rate was advanced by 2.9 days. Nitrogen fertilizer application had significant influence on biomass yield, grain yield, harvest index, number of productive ear, seed number per ear, and 1000-grain weight. Compared with traditional nitrogen application treatment, biomass yield of maize in the treatment postponing of application of 20% of N was increased by 6.6%, but not significant between the treatment with postponing of application of 10% of N and the traditional treatment. Similarly, grain yield of maize in the treatment with postponing of application of 20% and 10% of N was respectively, increased by 14.1% and 5.5%. The harvest index of maize in treatment with postponing of application of 20% of N was increased by 7.5%, but not significant between the treatment with postponing of application of 10% of N and the traditional treatment. Compared with traditional nitrogen application, the number of productive ear, seed number per ear, 1000-grain weight of maize in the treatment with postponing of application of 20% of N were increased by 8.9%, 12.9%, 5.8%, respectively, however, 1000-grain weight of maize in the treatment with postponing of application of 10% of N was not significant. The facts showed that the treatment with postponing of application of 20% of N has regulated grain yield with the improvement of number of productive ear and the enhancement of seed number per ear and 1000-grain weight. 【Conclusion】The treatment with postponing of application of 20% of N, (i.e. N application with 45 kg·hm^-2 at maize jointing, 180 kg·hm^-2 at pre-tasseling stage, and 135 kg·hm^-2 at 10 days post-flowering stage of maize) could be considered as the best feasible nitrogen fertilizer management for optimizing dry matter accumulation and obtain high yield for maize in oasis irrigation region.