A Study On The Effects Of Different Shade-tree Species On The Environment Of Tea Plantations And Tea Leaves Quality

The author has studied the atmospheric and soil condition differences between monoculturing tea plantation and Chinese fir-tea plantation in Weimo tea farm and also investigated the distribution and accumulation of heavy metal and sulfur elements in tea leaves .shade trees and soil in other four types of intercropping plantations .The four shade tree species included Water fir(Metasequoia glyptostroboides),Chinese bayberry(Myrica rubra L.),Ginkgo(Ginkgo biloba L.),Loquat(Eriobotrya bengalensis Hook.f.). Some the theoretical basis for the selection of shade trees has been proposed. The main results were described as follows :1.The content of TSP in pure tea plantation was 15.03% higher than that in Chinese fir-tea intercropping plantation.and was 56.44% higher than that in four types of ecological tea garden.The content of SO2 in pure tea plantation was 5.71% higher than that in Chinese fir-tea intercropping plantation, and was 23.33% higher than in that four types of ecological tea garden.2. The amount of dust absorption of tea leaves in pure tea plantation was higher than that in Chinese fir-tea intercropping plantation; while the amount of dust absorption of old tea leaves was higher than that of tender leaves.3.The dust absorption abilities of four shade trees was Loquat> Ginkgo> Chinese bayberry > Chinese fir and the differences among them were extremely remarkable. The shade trees could be ranked as : Chinese bayberry > Ginkgo > Water fir > Loquat , according to the amount of dust absorption of tea leaves planted under them.4.In the monoculturing tea plantation,the elements ranked as Mn>S>Zn>Ni>Cu>Pb according to their concentrations in the soil.With the increase of soil depth, the contents of Pb, Zn, S decreased, while the contents of Ni, Cu, Mn increased. In Chinese fir-tea intercropping plantation ,the sequence of soil element contents was : S>Mn>Zn>Cu>Ni>Pb, and with the increase of siol depth ,the contents of Pb, Zn, Mn, S decreased, but the contents of Ni, Cu increased.5.The contents of Cu, S in Chinese fir-tea intercropping plantation soil were little higher than those in pure tea plantation ,but the contents of Pb, Ni, Mn, Zn were lower.6.The contents of Pb, Mn, Cu, Zn of tea leaves in monoculturing tea plantation were higher than those in Chinese fir-tea intercropping plantation, but the contents of Ni, S were lower.The contents of Pb, Mn, S of old tea leaves were higher than those of tender tea leaves,while the contents of Ni, Cu, Zn of old tea leaves were lower.7.The ranges of enrichment coefficients of tea leaves to Mn and S were 3.848-15.253 and 6.924-16.233 respectively,which indicated that tea leaves had strong enrichment to these two elements.8.The contents of six elements above-discribed of tea leaves intercropped with four shade species could be ordered as follows: Pb Ginkgo > Chinese bayberry > Water fir > Loquau N Water fir > Chinese bayberry > Ginkgo > Loquat , Mn Ginkgo > Water fir > Chinese bayberry > Loquat, Cu Ginkgo > Chinese bayberry > Loquat>Water fir, Zn Ginkgo > Chinese bayberry > Water fir > Loquat, S Chinese bayberry > Loquat > Ginkgo > Water fir.9. The sequence of accumulating soil heavy metal elements of different shade tree species could be elementally ordered as: Loquat > Water fir > Chinese bayberry > Ginkgo.based on the contents of six elements of tea leaves in different intercropping plantations.