基于产量和养分含量的旱地小麦施磷量和土壤有效磷优化

【目的】 探讨长期定位施磷条件下小麦产量、土壤有效磷水平及籽粒养分含量变化,为旱地小麦合理施用磷肥,提高产量、改善品质提供理论依据。【方法】 基于2004年在黄土高原开始的长期定位试验,于2014—2015、2015—2016和2016—2017连续3年取样,研究不同施磷量对小麦产量,生物量,产量构成,籽粒氮、磷、钾含量,土壤有效磷含量及磷吸收利用的影响。【结果】 与不施磷相比,长期施磷使小麦产量平均提高67%,生物量提高58%,穗数和穗粒数分别增加64%和8%,而千粒重降低7%。施磷量与小麦产量、生物量呈抛物线关系,获得最高产量6 465 kg·hm ^-2的施磷量为144 kg P₂O₅·hm ^-2。籽粒氮含量随施磷量增加而降低,磷和钾含量随施磷量增加而提高。土壤有效磷含量与施磷量呈显著正相关,小麦获得最高产量时播前和成熟期有效磷含量分别为16.9和20.4 mg·kg ^-1。磷吸收利用效率随施磷量增加而降低,施磷量提高50 kg P₂O₅·hm ^-2,需磷量增加0.4 g·kg ^-1,磷收获指数降低1.3%,生理效率降低45.1 kg·kg ^-1。【结论】 综合考虑小麦的籽粒产量和关键养分含量,研究区域旱地小麦应以95%的最高产量为实际生产目标,施磷量为94 kg P₂O₅·hm ^-2,播前土壤有效磷为12.0 mg·kg ^-1,成熟期为13.8 mg·kg ^-1。

Optimization of Phosphorus Rate and Soil Available Phosphorus Based on Grain Yield and Nutrient Contents in Dryland Wheat Production

【Objective】It is of great importance to explore the wheat grain yield, soil available phosphorus (P) and grain nutrient contents under a long term P application at different rates, for the purpose of appropriate P application, wheat yield increase and improvement of nutritional quality in drylands.【Method】Field experiments were conducted to investigate the effects of different phosphorus (P) rates on wheat yield, biomass, yield components, grain nitrogen (N)-, P- and potassium (K)-contents, soil available P content, and P absorption and utilization, based on the long-term fixed field experiment which was initiated in 2004 in the Loess Plateau. Soil and plant samples were collected in the consecutive experimental years of 2014-2015, 2015-2016 and 2016-2017. 【Result】 The three-year averaged results showed that long-term application of P increased wheat yield, biomass, spike number and grains per spike by 67%, 58%, 64% and 8%, respectively, while 1000-grain weight was decreased by 7% compared with no P application. The wheat yield and biomass were quadratically correlated with the P rate, and the maximum wheat yield was 6 465 kg·hm ^-2 at P rate of 144 kg P₂O₅·hm ^-2. The P and K content of grain increased with the P rate increasing, while the N content showed an opposite trend. There was a significant positive correlation between the soil available P content and the P rate. The soil available P was 16.9 mg·kg ^-1at sowing and 20.4 mg·kg ^-1at harvest when the maximum yield was occurred. The P absorption and utilization efficiency decreased with the increased of P rate. For each 50 kg P₂O₅·hm ^-2 increment, the P requirement increased by 0.4 g·kg ^-1 for the grain yield formation, while the P harvest index and the P physiological efficiency decreased by 1.3% and 45.1 kg·kg ^-1, respectively. 【Conclusion】 By balancing the wheat grain yield and key nutrient contents, the target grain yield should be 95% of the maximum yield in drylands of the experimental area, and the corresponding P application rate should be kept at 94 kg P₂O₅·hm ^-2, the available P at 12.0 and 13.8 mg·kg ^-1 at sowing and harvest, respectively.