Research And Utilization Of Biological Characteristics Of Big Tea Trees In Linzhi City

Tea[Camellia sinensis（L.）O.Ktze.]belongs to the Camellia genus of the Theaceae family.It is a perennial evergreen woody plant native to China and has high economic and ecological value.Bomi County and Motuo County in Linzhi City,Tibet have good geographical environment and cultural characteristics,making them advantageous areas for tea production in Tibet.The large tea tree resources in Linzhi City have high research value,but have not yet received comprehensive investigation,analysis,and effective protection.It is urgent to carry out a comprehensive investigation,analysis,and evaluation.This study conducted a survey on the distribution of large tea tree resources that grow and develop in the wild state in Linzhi City,and conducted a systematic study and preliminary identification,analysis and evaluation of the biological characteristics,main biochemical components,and tea making quality of large tea trees.Through the investigation and research of large tea trees in Linzhi City,it can lay the foundation for cultivating new varieties of local tea trees in Tibet,and provide scientific basis for the protection and utilization of large tea tree resources and the sustainable development of the tea industry in Linzhi City.The research results are as follows:（1）The distribution,habitat,morphological characteristics,and photosynthetic characteristics of large tea tree resources in Linzhi City were investigated and measured.The resources of large tea trees in Linzhi City are mainly distributed in the Yigong Tea Farm of Linzhi City,and Xiabulong Village,Gedang Township,Motuo County,Linzhi City,and Yigongbai Village,Dexing Township,Motuo County.The three survey points have an altitude range of 1821-1998 meters,an annual average temperature range of9～12℃,and a soil p H value between 5.80 and 6.51.The ecological environment of the three survey points is suitable for the growth of tea trees.Xiabulong Village and Yigong Tea Farm belong to the middle leaf type of small trees,with mostly semi developed tree postures;Yigongbai Village belongs to the middle leaf type of shrubs,with a tree posture of opening;The number of petals at three survey points is 6-8,the stigma is 3-lobed,the ovary is hairy,and the fruit shape in Bulong Village is mainly triangular,while in Yigongbai Village and Yigong Tea Farm,it is mainly kidney shaped;The seed shape is mainly spherical and the color is brown.The light response curve and CO₂ curve reflect that the growth trend of large tea trees in Yigong Tea Farm is better than that in Xiabulong Village and Yigongbai Village.（2）The main chemical components of fresh tea leaves from major tea trees in Linzhi City were detected and analyzed.The results showed that the average content of tea polyphenols in the three survey points ranged from30.03%to 33.5%;The average amino acid content in Xiabulong Village and Yigongbai Village is 4.20%and 4.26%,both of which are higher than the average amount of cultivated tea in China;It can be used as an excellent germplasm breeding resource with high tea polyphenols and amino acids;The average range of caffeine content is 2.91%～3.17%,which is relatively low compared to the cultivation of tea trees in China;The ammonia phenol ratio range for the three survey points is between 7.06 and 9.15.（3）A sensory evaluation was conducted on green and black tea produced by the large tea trees in Linzhi City.The results showed that the roasted green tea produced by Xiabulong Village and Yigongbai Village had tight strands,a clear appearance,an emerald green color,a bright green soup color,a high chestnut aroma,a fresh and mellow taste,a uniform and fresh green leaf base,high sensory evaluation scores,and the best quality;The black tea produced by Yigong Tea Farm has tight and knotted strands,a dark and delicate color,a bright red soup color,a long-lasting fruity aroma,a sweet and rich flavor,and a uniform red leaf bottom.It has the highest official evaluation score and the best quality.By combining the content of main biochemical components such as amino acids,tea polyphenols,water extracts,caffeine,and the ratio of ammonia to phenol,the final conclusion can be drawn that the fresh leaves of large tea trees in Xiabulong Village and Yigongbai Village are more suitable for producing green tea,while the fresh leaves of large tea trees in Yigong Tea Farm are more suitable for producing black tea.