Objective The effects of shading in summer on the growth of different leaf positions and the accumulation of leaf positions of kucha were studied, and the suitable shading intensity was selected for the cultivation of kucha varieties, so as to provide theoretical basis for the cultivation of kucha varieties and the improvement of tea quality.

Method Setting up shading test, and the effects of different shading treatments on the growth of different leaf positions of kucha and the accumulation of catechins and purine alkaloids were analyzed.

Result Compared with the full light control group, using the shading rate of 65% and 85% could promote the early germination of kucha ‘Zimailongyun’, each phenological stage of shading group were advanced, and the bud and leaves of kucha after the shading treatment were thicker, greener and better growth. The leaves of the single bud, the first leaf and the second leaf were the heaviest under shading rate of 85%. The content of catechin (C), epicatechin (EC), gallocatechin (GC) and gallocatechin (GCG) in buds and leaves of kucha decreased with the increase of shading rate. From the first leaf to the fifth leaf, the contents of theacrine (TCR), purine alkaloids, epigallocatechin gallate (EGCG) in leaves in shading group were higher than those in control group, while the contents of caffeine (CAF) and non-ester catechin were opposite. The content of ester catechin in single bud and the first leaf decreased gradually with the increase of shading rate. From the second leaf to the fifth leaf, the content of ester catechin in shading group was higher than that in CK group.

Conclusion Shading treatment of kucha ‘Zimailongyun’ with shading rate of 65% and 85% not only beneficial to its growth and the accumulation of functional components EGCG and TCR in the leaves, but also reduces the content of CAF in leaves. Under the shading rate of 85%, higher yield of tender and fresh leaves of ‘Zimailongyun’ could be obtained. Combined with actual production, it was recommended to use shading nets with shading rate of about 85% for shading cultivation of kucha variety in order to achieve the purpose of effectively improve the quality and yield of summer tea of kucha.