不同供钾水平对茶树幼苗鲜叶主要生化成分的影响

本研究以10月龄扦插"瑞香"茶苗[Camellia sinensis(L.)O.Kuntze cv.Ruixiang]为试验材料,通过沙培试验,设5个钾(K)浓度(0、100、400、800、2 000μmol·L~(-1)),每周施钾肥3次,处理26周后,研究不同钾浓度对茶苗叶片主要生化成分的影响。结果表明,当供钾浓度分别为0、100μmol·L~(-1)时,茶树成熟叶片钾含量分别为5.26、5.91 mg·g-1,此时茶树处于缺钾状态,缺钾降低了茶树根、茎叶的生物量,增加了根冠比,显著降低叶片氮(N)和磷(P)的含量;叶片钾含量与氮、磷含量均呈正的线性相关(YN=1.045X+11.906 5,R2=0.816 7;YP=0.307 5X-0.570 6,R2=0.914 6);缺钾显著降低了茶树叶片氨基酸、咖啡碱、水浸出物和EGCG含量,相反却显著增加了叶片的茶多酚含量、儿茶素总量、酚氨比,以及叶片EGC和EC含量;叶片精氨酸、茶氨酸、谷氨酸等在缺钾时显著降低,与正常供钾浓度(2 000μmol·L~(-1))的叶片相比分别下降了86.96%、72.46%、40.43%;香气成分GC-MS分析表明,缺钾叶片醇类、醛类和酯类芳香物质含量降低,香气物质种类减少,缺钾对茶树叶片香气品质的提高具有消极的影响。

Effects of Different Potassium Levels on Main Biochemical Components of Fresh Leaves of Tea Seedlings

Vegetatively propagated 10-month-old tea [Camellia sinensis (L.) O. Kuntze cv. Ruixiang] seedlings grown in pots were fertilized three times weekly for 26 weeks with nutrient solution containing 0, 100, 400, 800 or 2000 μmol·L-1 potassium. The effects of different potassium concentrations on the nutritional elements (N, P, K), biochemical and aroma components of tea seedlings were studied. The results showed that the tea plants exhibited potassium deficiency when the potassium concentration was 0 or 100 μmol·L-1. The potassium contents in the mature leaves of the tea plants were 5.26 mg·g-1 and 5.91 mg·g-1, correspondingly. The K-deficiency decreased the root and shoot biomasses, but increased the the ratio of root to shoot. Leaf K content was positively correlated with N and P levels (YN=1.045X+11.9065, R2=0.8167. YP=0.3075X-0.5706, R2 =0.9146 ). Results also showed that K-deficiency decreased the contents of amino acid, caffeine, water extract and EGCG, but increased the contents of tea polyphenol, catechins, EGC, EC and the ratio of tea polyphenol to anmin acid. The contents of arginine, theanine and glutamic acid were significantly decreased in the K-deficient leaves as compared with leaves under normal potassium supply (2000 μmol·L-1), which decreased by 86.96%, 72.46% and 40.43% respectively. Aroma component analysis showed that the K-deficient leaves had lower alcohols, aldehydes and esters. Potassium deficiency had a negative effect on the aroma quality of tea leaves.