玉米/花生间作体系活化吸收土壤磷、铁和锌及其向籽粒转移的机制

Intecropping and phosphorus fertilizer dosages all influence grain mineral concentrations of phosphorus (P), iron (Fe) and zinc (Zn) in peanut and maize, thus affecting grain nutritional quality and human health. However, less was known about the machanism of P, Fe and Zn mobilization and uptake from soil and allocation to grain in maize/peanut intercropping system, especially under the field conditions...The present research is to determine dynamics of P, Fe and Zn accumulation and distribution in plant and corresponding characteristics of root growth, root morphology and distribution and rhizosphere physiological traits in intercropping system of maize/peanut with different application levels of phosphorus fertilizer under the field conditions...The aim of this work is to (1) elucidate the situation of P, Fe and Zn accumulation and distribution in plant, (2) to reveal the influence mechanism of underground interspecific root interactions and rhizosphere process for sparingly soluble P, Fe and Zn mobilization and absorption, (3) to clarify the regulation mechanism of different phosphorus fertilizer dosages on changes of grain mineral concentrations of P, Fe and Zn caused by plant-soil interaction processes in maize/peanut intercropping under the field conditions...This project can provide the theoretical basis for farmland phosphorus management, alleviating the conflicts between cereal and oil crops in land occupation and improving yield and nutritional quality of both maize and peant. It would provide theroetical and practical significance for sustainable development of ecological agraiculture through farmlang biodiversity increase.

间套作和磷肥供应强度均影响花生和玉米籽粒磷、铁和锌的浓度等营养品质，进而影响人体饮食健康，而田间条件下玉米/花生间作体系磷、铁和锌从土壤活化吸收和向籽粒累积分配的机制缺乏系统研究。本项目拟通过对田间不同供磷水平下玉米/花生间作体系磷和微量元素铁、锌在植株体内累积分配动态及根系生长、形态分布和根际生理特性动态的研究，阐明田间实际情况下玉米/花生间作体系磷和铁、锌在植株体内累积分配的规律，揭示地下部种间根系相互作用和根际过程对磷、铁和锌难溶性养分活化和吸收的影响机制，明确间作体系籽粒磷、铁和锌营养变化的作物-土壤互作过程及受供磷强度的调控作用。这方面的研究能够为农田磷素管理、缓解粮油争地矛盾、实现粮油增产和提升粮食品质提供理论依据，对通过增加农田生物多样性发展可持续生态农业具有一定的理论和实际意义。

作物群体密度和施肥量影响间套作产量和养分吸收优势。该项目通过在田间开展磷肥梯度和密度调控试验，揭示了供磷水平和玉米密度对玉米/花生间作体系产量、磷、铁和锌养分累积分配的影响规律。.（1）体系籽粒产量土地利用当量比（LER）小于1.0，处于间作劣势，而生物学产量和磷、铁和锌吸收量的LER大于1.0，具有间作优势。.（2）增加玉米密度提高间作玉米产量、磷、铁和锌吸收量，降低花生产量。.（3）花生籽粒产量偏土地利用当量比（PLER）明显低于生物学产量和磷、铁和锌吸收量的PLER。.（4）间作花生籽粒产量、磷、铁和锌的收获指数显著低于单作是间作体系籽粒产量劣势的主要原因；间作玉米密度越大，花生籽仁收获指数越低；间作花生根系和根瘤生长受到玉米的显著抑制，为产量和养分累积规律提供了直接证据。.（5）间作导致玉米籽粒磷的“富集”；间作玉米种植密度降低，玉米茎叶磷的质量分数增加，而籽粒铁和锌的质量分数表现出一定的“稀释效应”。.（6）施磷增加玉米和花生产量、磷和锌吸收量以及玉米籽粒磷、铁和锌的浓度。2017年施磷量对间作玉米产量和磷吸收量的偏土地利用当量比存在显著影响，40 kg/ha纯磷数值最高。.（7）过度缩小间作玉米株距（≤ 16 cm），降低生产力的空间稳定性，且导致玉米穗畸形和花生秧多果少。.通过对沿黄河流域跨区域多点多年的试验数据进行分析，揭示了供磷水平对间套作玉米磷素吸收分配影响规律。.（1）间套作玉米籽粒磷素浓度相对于单作的显著提高，导致磷素相对于干物质累积的更大优势和“奢侈吸收”。间套作玉米籽粒磷浓度，从单作1.89-2.91 mg/kg提高到2.09-3.65 mg/kg，增幅8.3-25.5%；植株体内磷素利用效率，从单作411.7-775.7 kg/kg降低到345.7-710.4 kg/kg，降幅4.9-16.0%；百公斤籽粒需磷量，从单作0.25-0.46 kg提高到0.27-0.54 kg，增幅7.0-17.4%。.（2）合理的施磷量最大化间套作玉米产量和磷素吸收量，过高施磷量降低植株体内磷素利用效率，增加百公斤籽粒需磷量。.综上，玉米/花生间作体系合理增加玉米密度和磷肥用量才能维持两种作物之间的平衡和发挥综合产量和养分吸收优势。