Abstract: Shading is one of the important measures to improve the quality of summer and autumn tea. There were a lot of studies on the effect of shading on tea leaves, but there were few reports on the root system. In this study, a pot experiment was used to explore the dynamic changes of physiological indexes and antioxidant enzyme activities of ‘Xiangfeicui’ and ‘Jinxuan’ under 95% shading treatment. Data were collected after shading for 0, 4, 12 d and the 4 d after regaining light. The results show that the number of new absorbing roots and lateral roots of tea plants increased after shading for 12 d, and decreased on the 4th day after regaining light. The trends of root vigor changes were the same. The soluble sugar content of ‘Xiangfeicui’ increased after shading, and the soluble sugars of ‘Xiangfeicui’ and ‘Jinxuan’ increased by 5.82% and 8.04% on the 4th day after regaining light. On the 4th day of heavy shading, the APX and POD activities of the two cultivars reached the peaks. On the 12th day of shading, the activities of SOD and APX the highest. The APX activity of tea roots after regaining light was significantly higher than that without shading. This study reveals that the roots of tea plants were osmotically regulated by increasing the content of soluble sugars, enhancing root vigor to absorb and transport nutrients, and increasing antioxidant enzyme activities to scavenging free radicals in response to heavy shade environments. Under a shading environment (95%), ‘Jinxuan’ was more shade-tolerant, and regaining light might cause a certain degree of stress to the roots of tea plants.

Key words: Camellia sinensis, shading, root vigor, antioxidant enzyme, root physiology