秸秆全量还田条件下玉米磷素吸收特征与磷肥适宜用量研究

  【目的】  探究长期秸秆全量深翻还田后玉米磷素累积特征及产量变化，以期为确定秸秆全量还田条件下的磷肥适宜用量提供理论依据。  【方法】  本试验于2017—2019年在吉林省公主岭市和朝阳坡镇进行，双因素设计，主因素为磷肥水平，P₂O₅用量分别为0 kg/hm2 (P0)、45 kg/hm2 (P45)、90 kg/hm2 (P90)、135 kg/hm2 (P135)和180 kg/hm2 (P180)，副因素为玉米品种，分别为富民985 (Fumin 985)和翔玉211 (Xiangyu 211)。测定开花期及成熟期各部位磷素吸收量、产量及其构成。  【结果】  地点、年份和磷处理3个因素及其交互作用对玉米产量、收获穗数、穗粒数和百粒重均有极显著影响 (P<0.01)；P90处理的产量、收获穗数和百粒重均最高，较P0处理分别增加了14.4%、6.15%和5.78% (P<0.05)。与P0处理相比，2017—2019年两地的花前磷累积比例均有一定程度的增加，以P90处理的增幅最大，其中朝阳坡2018和2019年P90处理的花前磷累积比例较P0处理分别显著增加24.5%和15.5% (P<0.05)。玉米的磷吸收量特别是秸秆中的磷累积量较为稳定，受施磷水平的影响较小，但籽粒的磷累积量呈先升后降的趋势；与P0处理相比，2017年公主岭P90和P135两处理籽粒磷素吸收量增幅显著，分别为22.3%和14.6% (P<0.05)；2017—2019年朝阳坡P90处理的籽粒磷素吸收量显著提高，增幅为7.03%～12.5% (P<0.05)。当施磷水平为90 kg/hm2时，磷转运量、转运率和对籽粒的贡献率达到较高水平。通过一元二次方程将3年两点数据进行拟合，得出公主岭和朝阳坡最高产量分别为12161和12435 kg/hm2，对应的最佳经济施磷量分别为77.2和71.9 kg/hm2；两地拟合后的最佳经济施磷量为74.6 kg/hm2。  【结论】  当施磷水平小于90 kg/hm2时，增施磷肥对提高花前的磷累积比例、籽粒磷素吸收量、转运量、转运率和对籽粒的贡献率有积极作用。在多年秸秆全量深翻还田背景下，玉米施磷(P₂O₅)量在71.9～77.2 kg/hm2，可达到12 t/hm2的产量水平。

Phosphorus accumulation characteristics and suitable phosphorus application rate of maize under full straw returning

  【Objectives】  The effects of phosphorus (P) accumulation characteristics and maize yield under long-term full straw return to the field were investigated. We aim to provide a theoretical basis for the appropriate rate of P fertilizer application under the condition of full straw returning.  【Methods】  The experiment was conducted in Gongzhuling City and Chaoyangpo Town of Jilin Province from 2017 to 2019, using a two-factor design. The main factor was P level (P₂O₅) at 0 kg/hm2 (P0), 45 kg/hm2 (P45), 90 kg/hm2 (P90), 135 kg/hm2 (P135), and 180 kg/hm2 (P180), respectively. The secondary factor was maize cultivar Fumin 985 and Xiangyu 211. Yield and its composition, and P absorption of different parts at flowering and maturity stages were determined.  【Results】  Location, year, and P application levels significantly affected maize yield, panicle number, panicle grain number, and 100-grain weight. Further, the interaction of location, year, and phosphorus application affected maize yield, panicle number, panicle grain number, and 100-grain weight (P<0.01) . P90 had the highest yield, panicle number and 100-grain weight, which were increased by 14.4%, 6.15%, and 5.78% compared with P0. P accumulation ratio before anthesis increased at both sites from 2017 to 2019, compared with P0. P90 and Chaoyangpo recorded the highest P accumulation ratio. Under P90, P accumulation was increased by 24.5% and 15.5% in 2018 and 2019 than P0. Maize P absorption, especially the accumulation of straw, was relatively stable and less affected by P levels. However, P accumulation in maize grains increased at first and then decreased. Compared with P0, P absorption in grains at Gongzhuling under P90 and P135 increased by 22.3% and 14.6% (P<0.05) in 2017, respectively. From 2017 to 2019, the P absorption of grains in P90 at Chaoyangpo significantly increased by 7.03% to 12.5% (P<0.05). When the P application level was 90 kg/hm2, translocation rate and quantity and contribution rate to grain reached the highest level. According to the quadratic equation of one variable, the maximum yield of Gongzhuling and Chaoyangpo were 12161 kg/hm2 and 12435 kg/hm2, respectively, and the optimal economic fertilizer application rate was 77.2 kg/hm2 and 71.9 kg/hm2, respectively. The optimal economic P application rate was 74.6 kg/hm2 in the two experimental sites .  【Conclusions】  When P₂O₅ application level was less than 90 kg/hm2, increasing P application positively affected the P accumulation ratio before anthesis, P absorption in grain , translocation rate and quantity, and contribution rate to grain. Full straw return to the field could achieve a yield of 12 t/hm2 at P₂O₅ application rate of 71.9 to 77.2 kg/hm2.