Molecular Soil Biology 2025, Vol.16, No.5, 255-264 http://bioscipublisher.com/index.php/msb 257 3.2 Photosynthesis and chlorophyll stability Soil pH also indirectly affects the photosynthesis of leaves and the content of chlorophyll by influencing the absorption of nutrients by the root system. In saline-alkali soil, the leaves of bayberries grafted onto salt-tolerant rootstocks are darker in color, have higher chlorophyll levels, stronger photosynthesis, and the plants perform healthier. However, if salt-intolerant rootstocks are used, the leaves tend to turn yellow and lose their green color (Saeed et al., 2023). This indicates that maintaining an appropriate soil pH and a healthy root system is of great significance for sustaining chlorophyll and photosynthesis. 3.3 Water-use efficiency and stomatal regulation Soil pH can alter the structure and function of the root system, which will affect the absorption and utilization of water by the bayberry. Under the influence of pH changes, the root system may experience thickening of cell walls or the formation of a cork layer, which can reduce water loss and enhance water use efficiency in drought and adverse conditions. Meanwhile, a healthy root system also helps regulate stomatal opening and closing, maintain the balance of transpiration and photosynthesis, and thereby enhance the stress resistance of the plant (Song et al., 2011; Saeed et al., 2023). 3.4 Stress tolerance mechanisms (oxidative stress, ion homeostasis) Soil acidification can aggravate the toxicity of aluminium, leading to oxidative stress in the root system, a decline in the activity of antioxidant enzymes, damage to root tissue, and disruption of ionic balance. Some molecular-level studies have shown that bayberries can enhance their tolerance to adverse conditions such as drought and low temperatures by regulating transcription factors like bHLH and increasing the activity of antioxidant enzymes (such as APX). When the root system is healthy and the soil pH is appropriate, the homeostasis of rhizosphere ions is easier to maintain, which can reduce the toxicity of harmful ions such as aluminum and enhance the overall stress resistance of the plant (Chen et al., 2022; Xu et al., 2023) (Figure 1). Figure 1 A potential working model for bHLH10 response to abiotic stresses in M. rubra. Under drought and cold stress, activating the environmental stresses signaling pathway and stimulating downstream stress signal transduction in plant cells, the upregulated bHLH10 acts upstream of APX and directly regulates its expression by binding to the E-box motif of its promoter. The activated APX then promotes cytosolic ascorbate peroxidase accumulation to scavenge ROS content under environmental stresses (Adopted from Xu et al., 2023) 4 Impacts on Fruit Yield 4.1 Flowering and fruit set rates Soil pH has a significant impact on the flowering and fruit setting rates of bayberries. Studies have found that overly acidic soil can reduce the vitality of trees, decrease the microorganisms in the rhitrosphere, make flower
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