密植会显著改变玉米群体冠层和根系的数量与质量，化控能调节冠层结构与功能，耕法可通过调节根系时空分布间接影响地上部，三者耦合能够有效调控作物产量形成。本研究利用长期定位试验，设置密度（D1：60000株/hm-2，D2：90000株/hm-2）、耕法（T1：少耕，T2：常规耕作）与化控（R1：喷化控剂，R2：喷清水）三因素试验，分析了不同处理玉米产量及其形成过程和冠层光合特性。结果表明：（1）低密度（D1）条件下，少耕化控（T1R1）处理籽粒产量较常规垄作（T2R2）处理显著增加27%-40.5%，穗粒数显著增加19.6%-27.3%；高密度（D2）条件下，T1R1处理籽粒产量较T2R2处理显著增加22.9%-24.9%，穗粒数显著增加14%-21.3%。（2）在2个密度条件下，不同耕法和化控处理显著改变植株高度和穗位系数，D1密度下，T1R1处理较其他处理显著降低株高和穗位系数，降幅分别为6.1%-20%和10.6%-23.4%；D2密度下，T1R1处理较其他处理同样显著降低株高和穗位系数，降幅分别为9.3%-20.3%和6%-12.2%。（3）耕法和化控显著影响植株冠层结构。D1密度条件下，T1R1处理植株上层和中层叶向值较其他处理显著增加6.8%-22.1%和8.1%-35.1%，D2密度条件下，T1R1处理仅较T2R2处理表现稳定的显著差异。另外，化控显著降低玉米植株上部叶片的叶面积，T1R1处理较T1R2显著降低17.1%-25.6%，高密度条件下差异更为明显。化控同样显著影响植株上部冠层透光率，T1R1处理较T1R2显著增加30.7%-34%。（4）两个密度条件下，T1R1处理单位面积光能的吸收（ABS/CS0）、捕获（TR0/CS0）分别较T1R2显著增加10.4%-17.5%、10.4-20%，高密度条件下差异更为明显。综上可见，在密植条件下，少耕和化控耦合优化了玉米密植群体冠层结构，增强了对光能的截获、吸收与传递能力，最终达到显著增加籽粒产量的目的。

Maize dense planting will significantly change the quantity and quality of the population canopy and root system. Chemical regulators can regulate the canopy structure and function. And the tillage can indirectly affect the above ground growing by regulating the spatial and temporal distribution of the root system. These three methods effectively regulate crop yield formation. In this study, maize yield, its formation process and canopy photosynthetic characteristics of different treatments were analyzed using a three-factor experiment with long-term localization, setting up density (D1: 60,000 plants/hm-2, D2: 90,000 plants/hm-2), tillage method (T1: less tillage, T2: conventional tillage) and chemical regulators (R1: spraying chemical regulators regulators, R2: spraying water). The results showed that: (1) Under the condition of low density (D1), the grain yield of less tillage control (T1R1) treatment increased by 27% -40.5% compared with conventional ridge cropping (T2R2) treatment, and the number of ears increased by 19.6% -27.3%; Under the condition of high density (D2), grain yield in T1R1 treatment significantly increased by 22.9% to 24.9% and by 14% to 21.3% compared with T2R2 treatment. (2) Under two density conditions, the plant height and spike position coefficient were significantly changed by different tillage methods and chemical regulators treatments. At D1 density, T1R1 treatment significantly reduced the plant height and spike position coefficient compared with other treatments, decreasing by 6.1% -20% and 10.6% -23.4%, respectively; At D2 density, T1R1 treatment similarly significantly reduced plant height and spike position coefficients, ranging from 9.3% to 20.3% and 6% to 12.2%, respectively. (3) Tillage and chemical regulators significantly affected plant canopy structure. Under the condition of D1 density, the leaf orientation value of the upper and middle layers of T1R1 treatment was significantly increased by 6.8%-22.1% and 8.1%-35.1% compared with other treatments. In addition, chemical regulators significantly reduced the leaf area of the upper leaves of maize plants, and the T1R1 treatment was significantly reduced by 17.1%-25.6% compared with T1R2, and the difference was more obvious under high density conditions. Chemical regulators also significantly affected the light transmittance of the upper canopy of the plant, and the T1R1 treatment significantly increased by 30.7%-34% compared with the T1R2 treatment. (4) Under the two density conditions, the absorption (ABS/CS0) and capture (TR0/CS0) of light energy per unit area treated by T1R1 were significantly increased by 10.4%-17.5% and 10.4-20% compared with T1R2, respectively. more obvious. To sum up, under the condition of dense planting, the coupling of less tillage and chemical regulators optimizes the canopy structure of the densely planted maize population, enhances the interception, absorption and transmission of light energy, and finally achieves the purpose of significantly increasing the grain yield.

S513.062

吉林省自然科学基金(20190201027JC),国家玉米产业技术体系岗位专家(CARS-02-19)