| Tea tree,an important economic tree species,plays an important role in the process of economic and social development in China.Tea silkworm is a typical and common pest,which seriously damages the quality and yield of tea.However,the chemical defense measures such as spraying fertilizers not only cannot fundamentally repelling the pest,but also seriously threaten the quality of tea.Therefore,in order to reduce the pests and diseases of the tea plantation ecosystem,optimize the tea planting patterns,and then improve the tea yield and quality,in this study,the indoor pot planting method was adopted to analyse the changes of soil chemical properties,tea leaves nutrients,tea tree growth rate,tea quality,tea plantation's physical and chemical defenses under the different intercropping patterns(tea plantation monoculture,peanut+tea plantation,corn+tea plantation,peanut+tea plantation+corn)after the silkworms have eaten and harmed the tea trees from the perspective of increasing the biodiversity in the tea plantation growing environment.It mainly revealed the influence mechanism of tea plantation's physical and chemical defense characteristics under different intercroping patterns of tea trees,and provides theoretical basis and production guidance for optimizing tea planting patterns,improving tea plantation's defense ability and tea quality.The main research were as follows:The growth rate of the tea plantation varies greatly under different intercropping patterns.The growth rate of the tea plantation monoculture,peanut+tea plantation,corn+tea plantation and peanut+tea plantation+corn were:(0.043±0.024)cm/7d,(0.083±0.017)cm/7d,(0.068±0.039)cm/7d and(0.103±0.043)cm/7d,respectively.Which could be seen that the growth rate of tea trees in the peanut+tea plantation+corn and peanut+tea plantation patterns were relatively large,indicating that intercropping peanuts in the tea plantation is beneficial to increase the growth rate of the tea plantation.The soil chemical properties and the nutrients of tea leaves changed significantly under different intercropping patterns.The soil total phosphorus(TP),total nitrogen(TN),organic carbon(SOC),ammonium nitrogen(NH4+),nitrate nitrogen(NO3-)and total potassium(TK)content were higher in the tea plantation monoculture and peanut+tea plantation+corn patterns.In addition,compared with the tea plantation monoculture and corn+tea plantation patterns,the carbon(C),nitrogen(N),phosphorus(P)contents and chlorophyll SPAD values of tea leaves were significantly higher in the peanut+tea plantation and peanut+tea plantation+corn under different tea intercropping patterns,and the soluble sugar content were highest in the corn+tea trees and the peanut + tea plantation,indicating that there were high nutrient contents of the tea tree leaves in the patterns of the peanut+tea plantation+corn and peanut+tea plantation,which indicated that those two tea plantation intercropping patterns may help to improve the ability of the tea tree to adapt to the environment.Furthermore,the nitrogen to phosphorus ratio(N/P)was less than 14,indicating that the growth of tea plantation was limited by nitrogen.Redundancy analysis results showed that soil total nitrogen(TN),total phosphorus(TP),nitrate nitrogen(NO3-),ammonium nitrogen(NH4+),organic carbon(SOC),available potassium(AK)and p H were the main influencing factors of the nutrient changes in tea leaves under different intercropping patterns.Through analysis of tea biochemical components and aroma types under different intercropping patterns,it was found that,the patterns of the peanut+tea plantation had the highly amino acid content in tea,and lower contents of the polyphenols,caffeine,and the phenol-to-ammonia ratio,but there were many types of aroma compounds,and mainly with fresh leaf fragrance and wintergreen-like fragrance,which showed that the quality of the tea leaves in the pattern of peanut+tea plantation were better than that of other three tea plantation patterns.In addition,the results of redundant analysis of tea quality and soil physicochemical properties and tea nutrients under different intercropping patterns showed that tea qualities(tea biochemical components+aroma components)was affected by many factors such as the leaf total phosphorus,soluble sugar content,chlorophyll and total nitrogen,and the soil potassium,nitrate nitrogen and ammonium nitrogen,and the amount of those interpretation reached 87%.Therefore,it is necessary to vigorously improve non-biological conditions and improve the utilization rate of soil nutrients in the tea plantation system.Only by creating a suitable growth and living environment can it be more conducive to improving tea quality.An analysis of the physical and chemical defenses of tea plantation under different intercropping patterns revealed that,among the tea planting patterns,the dry weight per unit leaf area,leaf thickness and leaf silicification of the tea tree were the highest in the peanut+tea plantation+corn pattern,followed by the peanut+tea tree patterns.It showed that the tea tree had the best physical defense ability in the peanut+tea plantation+corn pattern,followed by the peanut + tea tree pattern.Secondary metabolites are a chemical defense reaction produced by plants after being affected by insects.In this study,the secondary metabolic substance content of the tea tree was the highest in the peanut+tea plantation pattern,followed by the peanut+tea plantation+ corn pattern,after the silkworms ate and harmed the tea plantation in different tea plantation intercropping patterns.Volatile compounds are a signal-transmitting substance,which was produced when the tea tree was infested,and it could play a role in attracting natural enemies,alerting and avoiding pests.In this study,there were 55 kinds of volatile compounds in the tea plantation monoculture,58 kinds of volatile compounds in the peanut+tea plantation;53 kinds of volatile compounds in the peanut+tea plantation+corn pattern and 33 kinds of volatile compounds in the corn + tea plantation.In addition,this study also found that aldehydes and lipid compounds accounted for the main part of the total volatiles of tea plantation in the tea plantation monoculture and peanut+tea plantation patterns,indicating that aldehydes and lipid compounds were mainly play the role of avoiding pests and attracting natural enemies in those two tea plantation intercropping patterns,while in the corn+tea plantation and peanut+tea plantation+corn patterns,aldehydes,alcohols and lipids were the main volatile compounds to avoid pests and attract natural enemies.In summary,this study showed that the tea tree had the best chemical defense ability in the peanut+tea plantation pattern,followed by the peanut+tea plantation+corn pattern.The above research showed that,tea intercropping could increase biodiversity,improve the growth rate of tea,improve the tea quality and the physical and chemical defense level to a certain extent,when compared with tea plantation monoculture.In particular,the quality and the defense ability of the tea plantation were the best in the peanut+tea plantation pattern,followed by the peanut+tea plantation+corn pattern,furthermore,the intercropping effect was not obvious in the corn+tea plantation pattern. |
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