不同施氮水平对超高产夏玉米氮磷钾积累与分配的影响

为探明不同施氮水平下玉米超高产(≥13 500 kg hm^-2)群体氮磷钾积累及分配规律，通过苏玉20、浚单20两品种3年不同氮肥运筹方案的试验，实现了籽粒最高产量14 753 kg hm^-2的目标。结果表明：(1)随着生育进程，两品种氮磷钾在植株、籽粒中积累逐渐增大，在叶片、茎秆、叶鞘中呈先单峰变化趋势，叶片氮钾峰值在大口期，磷峰值在开花期。增大灌浆期植株氮积累量及叶片氮转移率，促使成熟期籽粒氮磷较大积累量，利于超高产玉米群体的形成。(2)籽粒产量、1 kg氮生产籽粒量、氮肥的农学效率、氮素利用率、植株(及叶片、茎秆、叶鞘、籽粒等器官)氮磷钾含量在450 kg hm^-2施氮水平时达到最大值，其值(苏玉20)分别为14753 kg hm^-2、44.0 kg、19.24%、38.63%、335.4 kg hm^-2、178.2 kg hm^-2、230.7 kg hm^-2，过高过低施氮均使氮磷钾积累量及产量下降。(3)由两品种产量与施氮水平的回归方程，确定了超高产时的最佳施氮量、超高产施氮水平和最佳施氮范围，苏玉20分别为457.0 kg hm^-2、418.3~495.7 kg hm^-2、418.5~495.4 kg hm^-2；浚单20分别为452.7 kg hm^-2(最佳施氮量)、410.8~494.6 kg hm^-2 (最佳施氮范围)。

Effects of Nitrogen Application on Accumulation and Distribution of Nitrogen,Phosphorus, and Potassium of Summer Maize under Super-High Yield Conditions

Establishing a high quality population is an important prerequisite to achieve high grain yield. Nitrogen (N) application is one of the most important practices in maize (Zea mays L.) production and plays a critical role in regulating population quality. To explore the effects of N application on accumulation and distribution of N, phosphorus (P), and potassium (K) of summer maize under the conditions of super-high yield (≥13 500 kg ha^-1), we planted two maize cultivars (Suyu 20 and Xundan 20), wtih different N application levels across three years, and the highest grain yield reached to14 753 kg ha^-1. The results showed that in the growth process, N, P, K accumulation increased gradually in the plants and grains of Suyu 20 and Xundan 20, and showed a curvilinear change in leaves, stems and sheatheswith a peak value at trumpeting stage and anthesis stage, respectively. The increasing of N accumulation and transfer rate in leaves at filling stage promoted the N and P accumulation of grain at mature stage, leading to super-high yield groups. In Suyu 20, yield, grain production per kg N, N agronomy efficiency, N utilization efficiency, N, P, K content in leaves, stems and sheathes were the highest at 450 kg ha^-1 which were 14 753 kg ha^-1, 44.0 kg, 19.24%, 38.63%, 335.4 kg ha^-1, 178.2 kg ha^-1, 230.7 kg ha^-1, respectively. But N, P, K accumulation and yield decreased when N application level was too high or too low. According to the regression equations between N application rate and yield of two varieties, for Xundan 20 the optimal N amount was 457.0 kg ha^-1, the range of optimum N was 418.5-495.4 kg ha^-1, 418.3-495.7 kg ha^-1 for super-high yield groups; and for Xundan 20, the optimal N was 452.7 kg ha^-1, the range of optimum N was 410.8-494.6 kg ha^-1