Impacts of Ecological Shading by Roadside Trees on Tea Foliar Nutritional and Bioactive Components, Community Diversity of Insects and Soil Microbes in Tea Plantation

SIMPLE SUMMARY: Tea is an important cash crop and is deeply loved by people around the world. The production of tea is affected by a variety of factors, and a landscape of roadside trees exists in many tea plantation ecosystems. What is the impact of this type of landscape on the production of tea? The management of plant diseases and insect pests in tea gardens, as well as the enhancement of tea quality, have been shown to be facilitated by appropriately shading and intercropping with high-stalk crops. We evaluated the impact of a roadside tree landscape on tea production, in terms of tea quality, pest occurrence, and soil microbial diversity. The results showed that planting roadside trees and providing shade for tea plants were beneficial to the improvement of tea quality and pest control in tea gardens, as well as soil quality. The research results can provide assistance for the ecological planning and construction of tea garden landscapes. ABSTRACT: Roadside trees not only add aesthetic appeal to tea plantations, but also serve important ecological purposes for the shaded tea plants. In this study, we selected tea orchards with two access roads, from east to west (EW-road) and from south to north (SN-road), and the roadside trees formed three types of ecological shading of the adjoining tea plants; i.e., south shading (SS) by the roadside trees on the EW-road, and east shading and west shading (ES and WS) by the roadside trees on the SN-road. We studied the impacts of ecological shading by roadside trees on the tea plants, insects, and soil microbes in the tea plantation, by measuring the contents of soluble nutrients, bioactive compounds in the tea, and tea quality indices; and by investigating the population occurrence of key species of insects and calculating insect community indexes, while simultaneously assaying the soil microbiome. The results vividly demonstrated that the shading formed by roadside tree lines on the surrounding tea plantation (SS, ES, and WS) had adverse effects on the concentration of tea soluble sugars but enhanced the foliar contents of bioactive components and improved the overall tea quality, in contrast to the no-shading control tea plants. In addition, the roadside tree lines seemed to be beneficial for the tea plantation, as they reduced pest occurrence, and ES shading enhanced the microbial soil diversity in the rhizosphere of the tea plants.