The photosynthetic rate (Pn) and leaf area index (LAI) play an important role in dry matter production. To understand the role of Zn fertilizer in increasing the yield of winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) by regulating Pn and LAI, a field experiment with six Zn rates (0, 2.3, 5.7, 11.4, 22.7, and 34.1 kg Zn ha⁻¹) was conducted from 2013 to 2015 on a calcareous soil. Zinc application increased wheat and maize yield by 4–19% and 4–13%, respectively, across the 2 yr. The aboveground biomass, Pn, and LAI of both wheat and maize also significantly increased with increasing Zn rates. Structural equation modeling showed that the yield increase of wheat mainly depended on the Pn and LAI, whereas that of maize mainly depended on the Pn. The relationships of the Pn and LAI with shoot Zn concentrations followed a linear‐plateau trend for wheat and linear for maize. The optimal shoot Zn concentrations to obtain the maximal Pn and LAI of wheat were determined to be 46–49 mg kg⁻¹. Zinc application at 11.4 kg Zn ha⁻¹ was an optimal rate to guarantee yield attainment and Zn biofortification. The results of this study are useful for farmers to optimize their Zn fertilizer management in agricultural systems to obtain high yields.

中文翻译：

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锌剂量变化对小麦-玉米系统光合特性和生产力的影响

光合速率（Pn）和叶面积指数（LAI）在干物质生产中起重要作用。要了解锌肥通过调节Pn和LAI来增加冬小麦（Triticum aestivum L.）和夏玉米（Zea mays L.）产量的作用，这是六种锌含量（0，2.3，5.7，11.4）的田间试验，22.7和34.1 kg锌ha ^-1）于2013年至2015年在石灰性土壤上进行。在过去的两年中，锌的施用分别使小麦和玉米的产量增加了4-19％和4-13％。随着锌含量的增加，小麦和玉米的地上生物量，Pn和LAI也显着增加。结构方程模型表明，小麦的增产主要取决于Pn和LAI，而玉米的增产主要取决于Pn。小麦中的Pn和LAI与茎秆锌含量的关系呈线性-高原趋势，而玉米呈线性-高原趋势。获得小麦最大Pn和LAI的最佳枝锌浓度为46–49 mg kg ^-1。锌施用量为11.4 kg Zn ha ^-1是确保产量和锌生物强化的最佳速率。这项研究的结果对农民优化农业系统中的锌肥管理以获得高产很有用。