Effects Of N/P/K Ratio On The Quality Of Tea Leaves

Tea is one of the most important non-alcoholic beverage crops in the world.With the growing consumer demand,the area of tea plantations has gradually expanded,and tea production has continued to increase.Tea,as a plant to use leaves,the growth of tea trees requires a large amount of N,P,and K,which often needs to be met through fertilization.However,due to the lack of scientific fertilization guidance,tea farmers have some blindness in applying fertilizer.This study first investigated the N,P,and K ratios commonly used in fertilization for tea farmers in Wuyi Mountain.At the same time,154 samples of the Shuixian as the main cultivar of Wuyi Mountain were collected to determine the N,P,and K ratios.Based on this,three different N,P,and K fertilizer application experiments were conducted to study the effects on the yield and quality metabolites of Shuixian,with a view to selecting the optimal N,P,and K ratio for nutrient management in Wuyi Mountain gardens.The main results are as follows:(1)Through the collection and nutrient analysis of Shuixian samples in different rock areas of Wuyi Mountain,it was found that there were certain differences in the concentrations of N,P,and K of tea leves in different rock areas,and the concentration of N,P,and K in high-quality Zhengyan tea was lower than that of low-quality Zhou Tea;However,there was a relatively constant proportional relationship between the N,P,and K of tea in different rock areas,about 7-1-6.Combining the investigation of farming households’ fertilization habits and the research on the proportion of N,P,and K in Shuixian,three kinds of N,P,and K ratio fertilizers were designed,in which T1 was15-15-15,T2 was 18-8-18,T3 was 21-8-11.(2)Through analysis of the yield of Shuixian tea leaves,it was found that the fertilization with different ratios of N,P,and K had little effect on the number of buds and dry weight of buds for Shuixian in the three seasons.However,fertilization methods of T3 could be increased the ratio of standard leaves in Shuixian,and was significantly higher than T1 and T2.The results showed that appropriately reduced the total nutrient content had little effect on tea yield,while appropriately reduced the ratio of P and K was conducive to improve the production rate of tea.(3)Through analysis the concentration of N,P and K in Shuixian tea leaves,it was found that the season had a significant effect on the concentration of N,P and K in tea leaves.The concentration of N,P and K in spring tea was significantly higher than that of summer tea and autumn tea.The accumulation of N,P and K might help the formation of high quality of spring tea.As the seasons change,the concentration of N and K in summer tea and autumn tea gradually decreases.Different N,P and K ratios had a significant effect on the concentration of N and K in tea,especially in tea samples of T3,the concentrations of N and K were significantly higher than those of T1 and T2.In addition,the seasonal time and fertilization treatment had a common interaction on the P concentration of tea leaves.The results showed that fertilization with different ratios of N,P and K significantly affected the concentration of N,P and K in tea leaves.(4)Through targeted analysis of the main quality metabolites in Shuixian tea leaves revealed that the changes of main secondary metabolites in different seasons tea leaves are more obvious.The concentration of summer tea was generally higher than that of spring tea and autumn tea,including TP,the EGCG and ECG of main catechins,as well as FAA,theanine and caffeine.Fertilization with different ratios of N,P and K had the greatest effect on the concentration of FAA and theanine,especially in spring tea and summer tea,the FAA and theanine in the tea leaves of T3 were significantly higher than those of T1 and T2.At the same time,using the restrictive main axis analysis method(CPCo A)to analyze the aroma and non-targeted metabolites of tea leaves,it was found that different N,P and K fertilization treatments can explain the total variation of aroma and non-targeted metabolite components 13.789% and 13.981%(P<0.001).The results showed that fertilization with different ratio of N,P and K could change the quality-related metabolites of tea.(5)Through the analysis of the soil conditions in before and after fertilization at different seasons,it was found that no matter what kind of fertilizer was applied,the p H of the soil was significantly reduced,and the OM content was not changed.Immediately after fertilization,except that there was no significant changed in AN in T1 soil and AK in T3 soil,fertilization could significantly increase the content of AK,AP and AK in soil.There was a downward trend in fertility.At the same time,there were significant differences in soil fertility between different fertilization treatments.The content of AP in soils of T1 with the highest proportion of P was higher than T2 and T3,while the AK in T2 with the highest proportion of K was higher than T1 and T3 in the season of fertilization.The results showed that the ratio of N,P,and K in the fertilizer significantly affected the nutrient composition of the soil,which in turn affected the concentration of nutrient and metabolites in tea leaves.All above,in this study,through tea garden investigation and N,P and K fertilization experiment of Shuixian in Wuyi Mountain,it was found that different N,P,K fertilization ratios had little effect on tea yield in different seasons,but could significantly affect the production rate,nutrients,and quality of tea.Among them,T3,which reduced the ratio of P and K in the fertilizer,was not only beneficial to the improvement of the crude tea production rate and the formation of quality metabolites,but also could save resources and protect the ecological environment.This research result will provide an important theoretical basis for the scientific fertilization and rational planting of Shuixian in Wuyi rock tea.