Molecular Soil Biology 2025, Vol.16, No.5, 272-286 http://bioscipublisher.com/index.php/msb 275 substances that are harmful to the root system. Legumes usually have taproots and require a well-ventilated soil environment to take root deeply and coexist with rhizobia. Once the soil permeability is poor, rhizobia infection and nodulation will also be inhibited. For example, if the soil in pea continuous cropping fields is compacted and anoxic, the yield-increasing effect of rhizobia inoculation is significantly reduced. Improving soil drainage and aeration can effectively promote the healthy growth of legume roots. In high rainfall areas, measures such as digging trenches to drain moisture and adopting high-bed cultivation can reduce field waterlogging and increase soil oxygen content (Zaman et al., 2018). Deep plowing and deep loosening can break the plow bottom layer, increase soil macroporosity, and significantly improve the water permeability of clay (Wang et al., 2020). Experiments have shown that the use of straw mulching and no-tillage in the black soil area of Northeast China can reduce topsoil runoff and water evaporation, while improving the aeration of the 0 cm-20 cm soil layer, thereby playing a dual role of "moisture conservation and ventilation" in the middle and late stages of soybean growth. Therefore, for poorly drained soils, optimizing tillage and field engineering to improve its aeration is a necessary condition to ensure the health of legume roots and stable and high yields. Figure 1 Response of soybean to waterlogging stress at different growth stages under climatic regimes (Adopted from Gangana Gowdra et al., 2025) 3.3 Soil nutrient imbalance and salinity stress The imbalance or excess or deficiency of soil nutrient supply will have an adverse effect on legume crops. Imbalance of macronutrients such as nitrogen, phosphorus and potassium is common in farmland with long-term improper fertilization management. For example, excessive application of nitrogen fertilizer may inhibit the nitrogen fixation of legume nodules, resulting in a decrease in the nitrogen utilization efficiency of legumes (Ciampitti et al., 2021). Studies have found that high nitrogen environments reduce the expression of symbiotic nitrogenase in soybeans, thereby reducing the nitrogen contribution rate of nodules to plants. Therefore, in the legume-rhizobium system, the amount of chemical nitrogen fertilizer needs to be controlled to give full play to the biological nitrogen fixation function (Clovis et al., 2023). On the other hand, insufficient nutrients such as phosphorus and potassium or lack of trace elements also limit legume yields. For example, low available phosphorus in acidic red soil leads to poor root development of legumes and reduced flowering and pod setting. In
RkJQdWJsaXNoZXIy MjQ4ODYzNA==