Research On Ecological Mechanism Of Chestnut And Tea Compound System In Dabie Mountain

Chestnut (Castanea mollissima) forests have serious problems such as soil erosion and soil fertility decline. Tea(Camellia sinensis) is a suitable shrub species to grow under partial shade. The research began in2011in Anhui province with experimental plots established in Jinzhai county. The experiment included4m×4m spacing of chestnut intercropping tea (model Ⅰ);4m×8m line spacing of chestnut intercropping tea (model Ⅱ) and pure tea garden (model Ⅲ). I studied microclimate changes, tea leaf photosynthetic characteristics, soil properties and tea’s quality under different models. The results reveal the influence of different composite density on tea tree growth characteristics, aiming to find the reasonable chestnut-tea mixtures cultivation models. The main results were as follows:1The changes of soil nutrients under different modelsFor all models, content of organic matter, total nitrogen, mineralizable nitrogen, total phosphorus, available phosphorus, and available potassium declined, and the content of potassium increased with increasing of soil depth.For all models, the soil nutrients changed most obviously in spring, while in other seasons, the change of soil nutrients is not obvious; Within the same season, the trend of soil nutrient showed the order:mode Ⅰ>mode Ⅱ> mode Ⅲ. The content of organic matter, total nitrogen, mineralizable nitrogen, total phosphorus, available phosphorus, potassium and available potassium in model Ⅰ and mode Ⅱ were34.75%,34.76%;44.11%,41.92%;24.97%,13.70%;45.71%,25.71%;66.12%,31.27%;56.03%,20.56%;83.79%,38.97%higher than those in Model Ⅲ, respectively.2The changes of soil enzyme activity under different modelsThe change trend of catalase, urease, dehydrogenase, invertase in four seasons followed the order:summer>spring>autumn>winter. But the trend of polyphenol oxidase was:autumn> spring> summer and winter.The content of catalase in model Ⅰ and model Ⅱ was respectively30.54%and17.83% higher than those in model Ⅲ; the content of urease in model Ⅰ and model Ⅱ was40.31%and28.96%. higher than those in model Ⅲ; the content of dehydrogenase and invertase in mode Ⅰ and model Ⅱ was115.62%,44.73%and40.70%,26.51%. higher than those in model Ⅲ, respectively3The changes of tea’s quality in different modelsThe contents of amino acids, catechin, and caffeine were higher in spring than in summer. The content of tea’s amino acid showed a pattern of model Ⅰ>model Ⅱ> model Ⅲ in spring. Compared with model Ⅲ, The catechin contents of model Ⅰ and model Ⅱ was12.97%and6.4%lower in spring and31.57%and36.84%in summer, while the contents of caffeine in model Ⅰ and model Ⅱ was higher with31.18%and29.83%。4The changes in the different models of tea leaves’photosynthetic characteristicsWith light intensity and temperature increased, the net photosynthetic rate of model III (pure tea garden) reached the first peak at11:00in the morning (12.21μmol·m-2·s-1), then it decreased and hit a trough at14:00, called "noon break" phenomenon, the second high peak occurred at15:00(9.58μmol·m-2·s-1,78.4%of the first peak’sl2.21μmol·m-2·s-1). The net photosynthetic rate of model II reached the first peak at13:00(10.78μmol·m-2·s-1), and get the second peak at15:00(8.63μmol·m-2·s-1). The net photosynthetic rate of model I changed in a single peak curve, and it reached its peak at13:00. there is no "noon break" phenomenon happened in model I, and its net photosynthetic rate was higher than other two models during13:00to14.00.Tea leaves’ stomatal conductance and transpiration rate in model Ⅰ and model Ⅱ related in a positive correlation and showed in a single-peak curve; tea leaves’ stomatal conductance and transpiration rate in model Ⅲ showed in double peaks curve.Tea leaves of model Ⅰ, mode Ⅱ and model Ⅲ showed consistent response to light intensity. Its photosynthetic rate increased with the intensity of illumination, and decreased after a certain range of illumination; light compensation point of model Ⅱ and mode Ⅰ were lower than model Ⅲ,which decreased by11.95%and27.41%.5The changes in the microclimate under different modelsChestnut and tea compound mode can improve the microclimate in the tea garden.The daily changes of air relative humidity is decreased first and increased after in3models. Within the increase of light intensity and temperature, air relative humidity decreased and got its minimum at14:00, it would then arise with the decrease of light intensity. But air relative humidity of mode Ⅰ was significantly higher than model Ⅲ. Daily changes of photosynthetic active rate increased first and then decreased for all models, but the highest point of the PAR are not the same, model Ⅲ reach the peak at11:00, while the model Ⅰ and model Ⅱ got the highest point at13:00.