Effects Of Zinc On Tea Plant Growth And Tea Leaf Quality

Zinc (Zn) is an essential micronutrient for tea plants. In the current study, cutting seedling of three-genotype tea plants were grown in nutrient solutions with Zn concentration at 0.1 mg-L^-1, 1.0 mg-L^-1, 3.0 mg·L^-1 and 5.0 mg·L^-1 respectively. Effects of zinc on physiological and biochemical changes were studied in tea plant during growth, and the relationships between the yield and quality of tea leaves under different Zn supplies were also studied. Zn promoted the synthetic metabolism of tea plant and increased the yields of tea and improved quality of tea leaves at the range from 1.0 mg·L^-1 to 3.0 mg·L^-1Zn²⁺ activities:1. Zn increased contents of chlorophylls, activity of the Zn-requiring enzymes carbon andrase (CA), and strengthened photosynthesis of tea shoots.2. Zn increased contents of IA A, GA₃, ZT, and decreased contents of ABA, made the ability of growth of tea plants stronger, and improved dynamic changes of phytohormones in tea shoots to benefit for growth of tea plant.3. Zn enhanced activity of roots system, and increased volume of roots, and especially the absorbing roots. Thus the ability of absorbant and synthetic metabolism in the roots were strengthened, which supplied more materials and energy for better growth of shoots.4. Zn increased contents of organic compounds in new shoots such as polyphenols, caffeines, amino acid and saccharines, and improved tea leaves quality.5. Zn increased activity of enzymes such as NR, ICDH, G6PDH, which is beneficial to metabolism of carbon and nitrogen. The differences in the yield and quality of tea were obviously showed, especially, under conditions of 1.0 mg·L^-1 Zn²⁺ activities.In the study, however the damage of growth of tea plant was also observed the yield and quality of tea were decreased under 5.0 mg-L^-1 Zn²⁺ activities.The study also found that genotypic sensitivity to Zn on growth and quality of tea were different between three-genotype tea plants, the cultivars Zhuyeqi was best than other two,for its produced better yield and quality, especially under the condition of 1.0 mg-L"1 Zn2+ activities.In the study, it showed that the nutrient solution of 1.0 mg-L"1 Zn2+activities was optimum to the growth of tea plants and quality of tea leaves, and three-genotype tea plants showed the same results.