| Scientific fertilization and intercropping management have been found to alleviate soil acidification and enhance soil fertility,thereby promoting the improvement of tea quality and yield.To date,the effects of optimized fertilization and intercropping patterns on soil properties,tea quality and yield in strongly acidic tea plantations are still unclear,and there is few available data for different scale comparison and continuous sampling analysis."Fuyun No.6" tea plant was selected as the research objects of this study.The effects of different optimized fertilization(CK: traditional fertilization;CF: modified traditional fertilization;MF: modified traditional fertilization with magnesium fertilizer;BF: modified traditional fertilization with biochar;MBF: modified traditional fertilization with biochar and magnesium fertilizer)and intercropping patterns(ST: single tea plant;T-A: tea plant intercropping Acacia podalyriifolia)on soil propreties,tea quality and yield of strongly acidic tea plantation were investigated through different scale experiments in tea plantation,greenhouse and artificial climate box.The major results were as follows:(1)Effects of optimized fertilization on soil propreties,tea quality and yield in tea plantationsThe experiments of optimized fertilization were conducted for two consecutive years in a strongly acidic tea plantation.The results showed that the combined application of biochar and magnesium fertilizer was more beneficial to the improvement of soil propreties,tea quality and yield.After co-application of biochar and magnesium fertilizer,soil p H increased to 4.72,soil total carbon,ammonium nitrogen,exchangeable magnesium content and bacterial diversity increased.In addition,the contents free amino acids and water extract in tea were enhanced,and the average annual tea yield was increased by 24.34%.Therefore,the combined application of biochar and magnesium fertilizer is a potential optimized fertilization strategy for strongly acidic tea plantations.(2)Effects of optimized fertilization on soil propreties and tea quality in greenhouseBased on the findings of the optimized fertilization experiment in tea plantation,the experiments of combining different amounts of biochar and magnesium fertilizer were further conducted by controlling some environmental conditions in a greenhouse.The results showed that the combined application of proper amount of biochar and magnesium fertilizer had positive effects on soil properties and tea quality.soil p H was significantly increased by 18.18%,and soil total carbon,available potassium,exchangeable magnesium and other contents,microbial diversity and abundance of beneficial bacteria such as Devosia and Rhizombium were also elevated.Moreover,the contents of amino acid,caffeine and water extract in tea increased by 41.91%,48.84% and 8.84%,respectively,while the ratio of tea polyphenols to amino acids decreased significantly by 19.69%.In conclusion,the combined application of biochar and magnesium fertilizer is conducive to alleviating soil acidification,increasing soil nutrient content and the abundance of beneficial genera,thus improving tea quality.(3)Effects of optimized fertilization on soil propreties and tea quality in climate chamberBased on the findings of the optimized fertilization experiment in tea plantation and greenhouse,the experiments of combining different amounts of biochar and magnesium fertilizer were further conducted by precisely controlling environmental conditions in artificial climate chamber.The results showed that the soil p H was increased by 5.32% and the contents of soil total nitrogen,ammonium nitrogen,microbial carbon and nitrogen were significantly increased after magnesium fertilizer combined with 2% biochar treatment.In addition,the net photosynthetic rate and the contents of total chlorophyll and carotenoid were significantly increased by 97.19%,39.55% and 25.01%,respectively.Furthermore,the contents of amino acid,caffeine and water extract were elevated by 39.01%,46.87% and 18.19%,respectively.Moreover,the relative contents of some important aroma components,such as linalool and methyl salicylate were also enhanced.In conclusion,the combined application of magnesium fertilizer and 2% biochar effectively improved soil quality,promoted photosynthesis of tea plant,and thus improved tea quality.(4)Effects of A.podalyriifolia intercropping in tea plantation on soil propreties,tea quality and yieldThe experiments of different intercropping patterns were conducted in tea plantation by selecting legume A.podalyriifolia as the intercropping plant.The results showed that the soil p H increased by13.62% under tea plant intercropping A.podalyriifolia.Soil total nitrogen,ammonium nitrogen,exchangeable magnesium and soil microbial diversity index and the relative abundance of beneficial bacteria such as Gemmata and Microdochium also elevated.In addition,the contents of free amino acids and water extracts in tea enhanced,and the tea yield increased by 9.26%.Therefore,intercropping A.podalyriifolia had positive effects on soil propreties,tea quality and yield.(5)Effects of tea plant intercropping A.podalyriifolia in greenhouse on soil propreties and tea qualityBased on the findings of intercropping experiment in tea plantation,the experiments of tea plant-A.podalyriifolia intercropping were further conducted in a greenhouse.The results showed that the soil p H increased by 14.59%,and the contents of total nitrogen,ammonium nitrogen and available potassium also increased significantly under tea plant-A.podalyriifolia intercropping.Moreover,soil microbial community diversity and abundance of beneficial bacteria such as Microdochium and Setophoma also showed a rising trend.Furthermore,the contents of free amino acids,caffeine and water extract,and the relative contents of important aroma compounds such as myrcene and(Z)-linalool oxide in tea were also enhanced.In conclusion,rational application of biochar and magnesium fertilizer and intercropping A.podalyriifolia were conducive to improving soil propreties,tea quality and yield in strongly acidic tea plantations.The results provided a theoretical basis for improving the management strategy of strongly acidic tea plantations. |
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