Tea pruning for the umbrella-shaped canopy can alleviate rhizosphere soil degradation and improve the ecosystem functioning of tea orchards

Abstract

Leaf and branch pruning is essential for improving the productivity of continuously cropped leaf-harvested crops, such as tea, which is conductive to stabilize the production, delay the aging, and subsequently improve economic benefits. Generally, farmers adopt crew-cut pruning to get more yield in tea orchard pruning management. However, the long-term effects of crew-cut pruning on ecosystem of tea orchard are unclear. The present study investigated the environmental differences of ecosystem between crew-cut tea (CT) pruning and umbrella-shaped tea (UT) pruning treatments in the Tieguanyin tea orchards of China. We analyzed the soil enzymes activities, the rhizosphere and phyllosphere's microbial communities, the secondary metabolites of fresh tea shoots, and the insect abundance and its diversity in the two types of tea orchards. The results showed that both saccharase and urease were improved at different soil layers by UT. Fresh tea shoots analysis revealed 22.91% and 16.59% higher epigallocatechin gallate and epicatechin gallate levels, respectively under UT regime than those in CT, but a 9.42% lower ratio of polyphenol to the amino acid in comparision with that in CT. The total volatiles, especially (E)-geraniol and furanoid linalool oxides, in the fresh shoots of UT were also significantly higher than those in CT. Further analysis showed that UT had more beneficial insects than CT. In contrast, tea gardens in CT were at a higher risk of pest attack than that in UT. Prolonged umbrella pruning of tea plantations significantly improved the bacterial diversity and the beneficial fungi in the leaf surface. Moreover, the relative abundances of rhizobia and ammonia-oxidizing bacteria in the rhizosphere were higher in UT than that in CT. The findings suggest that tea pruning in umbrella-shaped can reduce rhizosphere soil degradation and improve the ecosystem functioning, suggesting that proper pruning pattern is needed to improve tea quality.