Molecular Plant Breeding 2025, Vol.16, No.4, 221-230 http://genbreedpublisher.com/index.php/mpb 223 Shading also helps enhance the resistance of tea plants, such as increasing the activity of antioxidant enzymes, which helps tea plants resist sudden strong light damage (Sano et al., 2020; Zaman et al., 2023). Figure 1 Effect of shading treatment on the chlorophyll content of tea leaves and the expression of related genes (Adopted from Chen et al., 2021) Image caption: (A) The phenotype of new shoots after 7 day and 14 day shading treatment. Bar=2 cm. (B) The comparison of leaf pigments after 7 day and 14 day shading treatment. (C) The change of chlorophyll content after shading treatment. Chl: total chlorophyll; Chl a: chlorophyll a; Chl b: chlorophyll b; and FW: fresh weight. (D) The changes in the gene expression of chlorophyll synthesis pathway after shading treatment. CK: no shading treatment group (about 1 300 μmol m-2 s-1); T: 90% shading treatment group (about 130 μmol m-2 s-1). CsEF1-α was used as an internal reference to normalized the changes. Data are expressed as mean±SD (n=3). *p≤0.05; **p≤0.01; and difference from CK treatment at the same time point (Adopted from Chen et al., 2021) 4 Role of Irrigation Frequency in Summer Tea Cultivation 4.1 Water stress and its influence on bud set and expansion Lack of water will significantly affect the sprouting of tea plants. Under water stress, the buds of tea plants fail to grow or grow slowly, the leaf activity deteriorates, the photosynthetic efficiency decreases, and eventually both yield and quality are affected (Yue et al., 2023). During drought, the metabolic activities and lipid components in tea plant leaves also undergo significant changes. Although some damages can partially recover after rehydration, the levels of many metabolites are difficult to fully return to normal (Figure 2) (Shen et al., 2022). So, scientific irrigation is a good way to solve this problem. As long as the water keeps up, the buds can differentiate and grow normally, and the yield and quality of tea in summer will also be better (Hasan et al., 2023). 4.2 Irrigation scheduling strategies in tea gardens In summer, it is very important to scientifically arrange irrigation. Some studies have pointed out that if tea plants are watered every 4 to 5 days and combined with an appropriate amount of nitrogen and phosphorus fertilizers, the accumulation of dry matter and the growth of new shoots can be significantly enhanced. Meanwhile, the intelligent irrigation system that utilizes remote sensing technology and soil moisture monitoring can also adjust the watering time and water usage according to the actual water shortage situation in the tea garden. This approach can not only ensure that tea plants have water to use, but also save water resources and improve efficiency (Wang et al., 2021). These practices help to achieve more meticulous management of tea gardens and reduce the damage caused by water shortage.
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