Tea plant variety classification and identification
Tea plant varieties are divided into two major categories based on propagation methods: sexual reproduction line varieties and asexual reproduction line varieties.
Varieties reproduced through sexual means (seeds) are called sexual reproduction line varieties, abbreviated as sexual line varieties; varieties reproduced through asexual means (cuttings, etc.) are called asexual reproduction line varieties, abbreviated as asexual line varieties.
In tea production, asexual line varieties with high economic value are often called asexual line improved varieties. Sexual line varieties, due to seed propagation, have obvious main roots in seedlings, forming a taproot system, and the plant characteristics within the population are relatively mixed and uneven; asexual line varieties are generally propagated by short-node cuttings, resulting in uniform characteristics among plants in the population. Seedlings from short-node cuttings lack a main root, forming a fibrous root system, and have a short-node scar at the root collar, making them relatively easy to identify.
The desirable characteristics of asexual line varieties can be passed down through generations, featuring high yield, excellent quality, strong tenderness retention of buds and leaves, uniform sprouting, consistent morphology and size of buds and leaves along with internal quality, and ease of harvesting and processing. Therefore, asexual line varieties are widely promoted and applied in tea production. For example, the Fuding Da Bai tea variety, originally from Fuding County, Fujian Province, despite having over 100 years of cultivation history, remains one of the improved varieties enthusiastically promoted in many tea regions. Tea plant varieties are all bred under the specific ecological conditions of a particular area. Varieties native to or bred in one area, when introduced and cultivated in other areas, are classified by adaptability as either adaptable or non-adaptable varieties. Adaptability refers to the requirements of the tea plant for normal growth and development regarding natural conditions such as temperature, light, frost-free period, precipitation, and soil acidity in the cultivation region. The adaptability of a variety can be assessed based on its performance in the introduced area, including growth vigor, stress resistance, yield, and quality.
If a particular variety of tea plant grows and develops well in the introduced area, shows strong stress resistance, retains tenderness in buds and leaves, achieves high yield, produces tea of excellent quality, and its overall performance is consistent with that in its original location, it indicates strong adaptability of this variety to that region. Tea plant varieties are classified by stress resistance into five categories: weak resistance, relatively weak resistance, strong resistance, relatively strong resistance, and high resistance. Stress resistance refers to the tea plant's tolerance or resistance to adverse environmental factors such as cold, drought, diseases, and pests. Generally, resistance is scored and graded using a 5-point system based on the damage degree of the leaves of each variety under these adverse factors, combined with the damage condition of branches and stems. Tea plant varieties are classified by sprouting period into four types: extra-early sprouting, early sprouting, mid-season sprouting, and late sprouting. The sprouting period of a tea variety is identified by observing the sprouting process of the overwintering axillary buds. The overwintering bud sprouting process is generally divided into four phenological stages: fish leaf stage, first leaf stage, second leaf stage, and third leaf stage.
Generally, the day when 20% of the axillary buds of a variety reach a certain phenological stage is considered the date when that variety reaches that stage. Observation of the sprouting period needs to be repeated for three years, using the Fuding Da Bai Cha variety as a control. Methods for observing the sprouting period of tea varieties include visual estimation and the tagging method. Visual estimation relies on experience, while the tagging method involves selecting 5-10 tea plants, tagging 5-10 axillary buds on each plant for observation to determine the sprouting period.
Under the same conditions, varieties that sprout more than 5 days earlier than the Fuding Da Bai Cha variety are classified as extra-early sprouting types; those sprouting up to 4 days earlier are early sprouting types; those sprouting up to 5 days later are mid-season sprouting types; and those sprouting more than 5 days later are late sprouting types. Tea plant varieties are also classified by the size of mature leaves into four categories: extra-large leaf varieties, large leaf varieties, medium leaf varieties, and small leaf varieties. Leaf size is compared by measuring leaf area (leaf length × leaf width × 0.7). A leaf area above 70 cm² is an extra-large leaf variety; between 40-69 cm² is a large leaf variety; between 21-39 cm² is a medium leaf variety; and 20 cm² or below is a small leaf variety.
Tea plant varieties are classified by yield into high-yield varieties and general varieties. Yield identification requires conditions of identical cultivation and management. Fresh leaves are harvested according to the plucking standard, yield is recorded, averaged over three years of repeated records, and converted into yield per unit area. Alternatively, fresh leaf yield can be divided by 4 to convert into dry tea yield. When统计ing yield, for green tea varieties or black tea varieties, fresh leaves are harvested and recorded based on the standard of one bud with two or three leaves. For oolong tea varieties, yield is recorded when new shoots have grown to 3-5 leaves, and about 70% of the terminal leaves have formed an open face, by harvesting the attached two or three leaves.
Tea plant varieties are classified by suitability for tea types into four categories: green tea varieties, black tea varieties, varieties suitable for both black and green tea, and oolong tea varieties. Among them, green tea varieties are further divided into those showing abundant trichomes (hao) for green tea and those with few trichomes, like the Longjing type flat-shaped green tea varieties.
Tea type suitability refers to the inherent varietal characteristics that constrain tea quality, meaning which type or types of high-quality tea a tea plant variety is most suitable for producing. The tea type suitability of a tea plant variety, abbreviated as suitability, can be indirectly evaluated by observing the physical characteristics and measuring the chemical characteristics of the buds and leaves. This is particularly common in the early stages of tea variety selection. Physical characteristics refer to the features and state of the buds and leaves on the new shoots of the tea plant, such as plumpness, size, leaf color, leaf texture, leaf thickness, softness, tenderness, and pubescence. These are closely related to the appearance quality of the finished tea.
Generally, varieties with small leaves, thick leaf blades, soft and tender leaf texture, green color, and abundant trichomes are suitable for making trichome-rich green teas, such as Maofeng, Maojian, Silver Bud, and other famous teas, easily shaping the quality characteristic of 'fully covered with white hairs, silver-clad'. Varieties with slender buds and leaves, yellow-green or light green leaf color, and few or moderately few trichomes are suitable for making low-trichome Longjing-type flat green teas, such as Longjing tea, easily forming the quality style of flat and smooth appearance, straight and sharp shape, bright green color, and hairless body surface. Varieties with large leaves, long internodes, plump buds, yellow-green buds and leaves, abundant trichomes, raised leaf surface, soft leaf texture, and thin leaf blades are better suited for making black tea.
Chemical characteristics refer to the content and composition of chemical components in the buds and leaves, which form the material basis for the color, aroma, and taste of tea.
The measurement of chemical characteristics generally involves collecting fresh leaves according to the one-bud-three-leaf standard, steaming them at 100°C for 3 minutes, drying them at 80°C to make steamed green tea samples, then grinding the samples for chemical component determination. Although the chemical characteristics of tea plant varieties are greatly influenced by the planting region's environment and cultivation conditions, the differences in chemical characteristics between different varieties under the same conditions are still evident.
Generally, varieties with high tea polyphenol content and a high ratio of tea polyphenols to amino acids (referred to as the phenol-ammonia ratio) produce high-quality black tea. Varieties with high amino acid content, suitable tea polyphenol content (around 16%-24%), and a small phenol-ammonia ratio produce high-quality green tea. For example, the Qianmei 419 variety, with steamed green tea containing 36.03% tea polyphenols, 1.4% amino acids, and a phenol-ammonia ratio of 25.7, produces black tea with a bright, red liquor, strong and fragrant aroma, and a strong, brisk taste, but when made into green tea, the taste is strong, bitter, and astringent. This indicates that Qianmei 419 is an excellent variety suitable for black tea. When the Fuding Da Bai Cha variety was introduced to Meitan, the average content of steamed spring and summer tea was 25.3% tea polyphenols, 1.89% amino acids, with a phenol-ammonia ratio of 13.4. It produces trichome-rich green tea with a green, bright appearance showing trichomes, and a persistent chestnut aroma, but the black tea made from it has a weak taste. This shows that Fuding Da Bai Cha is an excellent variety suitable for making trichome-rich green tea.
In production, the suitability of a tea plant variety is generally directly identified by processing the fresh leaves of the same variety into different types of tea and conducting sensory evaluation. When evaluating quality through sensory evaluation, a method combining scoring and descriptive terms is used. First, accurately weigh 3 grams of tea sample into the evaluation cup, then pour in about 150 milliliters of boiling water, steep for 5 minutes, and begin the evaluation.
According to the five-factor evaluation method, the quality of the tea is scored out of 100 points item by item for appearance, liquor color, aroma, taste, and infused leaves, and described with corresponding terms. Finally, the total score is calculated based on the quality weighting factors for appearance, liquor color, aroma, taste, and infused leaves. For famous and high-quality green tea, the total score is calculated using the weightings: appearance 30%, liquor color 10%, aroma 25%, taste 25%, and infused leaves 10%. The score level can directly reflect the superiority or inferiority of the variety's quality, i.e., the degree of suitability of a variety for a particular tea type, while the corresponding terms can describe the tea-making quality characteristics of different varieties. Since the quality requirements for different tea types vary, and the inherent suitability of each variety constrains the tea quality,加之 the differences in suitability between varieties are significant, a variety suitable for green tea may not be suitable for black tea, and a variety suitable for trichome-rich green tea may not be suitable for making low-trichome Longjing-type flat green tea.
Therefore, the suitability of tea plant varieties should be one of the key indicators considered in production selection. Only by choosing tea plant varieties with the correct suitability can high-quality tea products of the corresponding type be produced. Tea plant varieties can be classified by the approving authority into national-level varieties and provincial-level varieties. A newly bred variety, after identification of its sprouting period, stress resistance, yield, suitability, etc., must finally be approved by the provincial or national crop variety approval committee before it is allowed to be widely promoted and applied in production.
The standards for national-level tea plant variety approval are excerpted here to provide an overall understanding of national-level tea plant varieties. There are 3 criteria; meeting any one of them allows a variety to be approved as a national-level tea plant variety.
① The regional trial yield is more than 10% higher than the control variety, and statistical analysis reaches a significant level;
② The yield is similar to the control variety, but the quality is significantly superior to the control variety;
③ Certain characteristics are outstanding, possessing special utilization value, and the yield and quality are comparable to the control variety.