Molecular Plant Breeding 2025, Vol.16, No.4, 221-230 http://genbreedpublisher.com/index.php/mpb 227 controlling the watering frequency (Chen et al., 2023a). Overall, the practice of combining shading and irrigation has a promising promotion prospect in the tea-growing areas of Zhejiang Province and is also highly accepted by farmers. 9 Limitations and Research Gaps 9.1 Variability across tea varieties and regions Most current research focuses on a few common varieties, such as “Longjing 43” and “Fuding White Tea”, and the scope of research is mainly limited to some specific regions. In fact, different tea plant varieties and different ecological environments respond greatly to shading and irrigation. For instance, for some varieties, the quality components such as amino acids and tea polyphenols will change significantly after shading, but the same shading method has no obvious effect on another variety (Li et al., 2020; Hu et al., 2024). Some studies in emerging tea-growing areas such as the United States have found that the impact of shading on tea plants is quite different from that in traditional tea-growing areas, indicating that the origin environment and the genetic background of the variety may jointly affect the mechanism of shading and irrigation, but these have not been fully studied yet (Zhang et al., 2022). 9.2 Lack of molecular data linking treatments to gene expression Although some studies using transcriptome and metabolome analysis have found that shading affects some metabolic pathways in tea plants, such as the expression of genes that control amino acid, chlorophyll and flavonoid synthesis (Teng et al., 2020), but most of these studies only analyzed shading as one factor. There is not much molecular evidence that truly and systematically links shading, irrigation frequency and other field management measures to the expression of key genes related to tea quality. Especially, there is still a lack of in-depth molecular-level research on how shading and irrigation affect bud growth and tea quality through signal transduction, hormone regulation, etc. (Sun et al., 2020; Fang et al., 2022). 9.3 Short-term trials vs. long-term effects Most existing studies have been short-term treatments, such as shading or irrigation for 7 to 20 days, mainly focusing on the growth and quality changes of buds and leaves during this period (Zhu et al., 2023). However, in real production, shading and irrigation are often long-term management measures. In the long term, it remains unclear whether these treatments will affect the entire growth cycle, yield changes, quality stability, and even the stress resistance of tea plants. Some studies have found that prolonged shading may suppress the carbon and nitrogen metabolism of tea plants, having a negative impact on yield and quality (Li et al., 2020; Chen et al., 2023a). However, at present, there is still a lack of cross-seasonal and multi-year continuous observation data, which also makes it difficult for us to offer scientific and reliable long-term management suggestions to tea farmers. 10 Concluding Remarks Shading is an important method to improve the quality of tea in summer. Research has found that appropriate shading can significantly increase the content of amino acids in tea, especially umami amino acids and theanine. At the same time, it can also reduce polyphenols and bitter substances, making the color of the tea better and the taste more mellow. Methods like using double-layer shading nets not only improve the microclimate of the tea garden and lower the temperature, but also keep the soil moist, which helps the buds and leaves grow faster and the quality of the leaves is also higher. Shading can also regulate the metabolism of carbon and nitrogen, promote the synthesis of photosynthetic pigments, and at the same time control the expression of some related genes, making tea plants more adaptable to adverse conditions such as high temperatures and dryness, and also easier to accumulate beneficial substances. Shading works even better when combined with a reasonable irrigation frequency. Moderate watering can help maintain soil moisture and root vitality. As a result, not only will buds grow faster, but the quality of tea will also be higher. Studies show that in the hot and strong summer environment, the combination of shading and irrigation is a good way to scientifically manage tea gardens. As long as the right shading materials are selected, the degree of shading and the watering time are well controlled, the growth environment of tea plants can be better regulated,
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