Key Technical Points and Detailed Methods for the Breeding of Improved Tea Varieties

There are many methods for breeding superior tea varieties, mainly including systematic selection, crossbreeding, artificial mutation breeding, and introduction and acclimatization.

(1) Systematic selection: also called single-plant selection. That is, according to the breeding objective, superior single plants are selected from the selection materials, each single plant is separately propagated vegetatively, and compared and identified with the standard variety and the original population variety; the superior ones are cultivated into new varieties for propagation and promotion.

Its steps: ① Primary selection: according to the breeding objective and the correlation between tea plant traits, select a number of superior single plants in the tea garden, mark and number them for observation; ② Observation: this work must be carried out throughout the year, grasping the performance in different seasons, repeated for 2-4 years. Observation items include tree type, tree posture, new bud sprouting and new shoot growth, bud and leaf traits, stress resistance, single-plant yield, tea-making quality, suitability for processing, etc.; ③ Re-selection: based on the comprehensive analysis results of the observation records, decide whether to keep or discard, and this may be carried out several times; ④ Preliminary propagation: propagate a certain number of seedlings separately from the selected single plants for strain comparison trials. At the same time, understand their reproductive capacity; ⑤ Strain comparison trial: the vegetative progeny of the selected single plants are called strains. Use a representative qualified improved variety or the local main planted variety as the standard variety, and compare it with vegetative clones of the same age. The items for comparison and identification include quality, suitability for processing, yield, stress resistance, plucking period, annual sprouting rounds, sprouting density, and bud and leaf traits, etc.; ⑥ Report for approval. The improved varieties selected through strain comparison trials and regional adaptability trials can be reported to the provincial crop variety approval committee for approval; improved varieties to be promoted across provinces are reported to the national crop variety approval committee for approval; ⑦ Propagation and promotion: improved varieties that pass approval can be propagated and promoted.

(2) Sexual crossbreeding: Tea plants with different heredity produce hybrid progeny through the combination of male and female sex cells, and the process of creating new varieties through cultivation and selection is called tea sexual crossbreeding. It basically consists of three main links: hybridization, selection, and vegetative propagation.

Its technical points: ① Correctly select parents. Use materials with relatively distant kinship and relatively large ecological type differences as parents; the comprehensive traits of both parents should meet the requirements of the breeding objective; the flowering periods of the male and female parents should be close; the female parent must have fruit-setting ability; ② Grasp the timing and operate carefully. When the male parent flowers are fully mature and about to open but not yet open, collect their pollen for later use; when the female parent flower is at the bud stage about to bloom, gently peel open the petals, dip a writing brush into some male parent pollen and apply it to the stigma of the female parent, then immediately bag and isolate; ③ Strengthen management after pollination: the bag can be removed 3-5 days after pollination. If the stigma withers and the calyx closes, it indicates that the ovary has been fertilized, and care should be taken to protect the young fruit and prevent it from dropping; ④ Carefully cultivate and select: after the seeds of the hybrid progeny are obtained and sown, single-plant selection and comparison trials must be carefully carried out according to the breeding objective before a new improved variety can be bred; ⑤ Apply for approval, propagate and promote: the bred improved variety should be reported for approval according to the relevant prescribed procedures, and after passing approval, it can be propagated and promoted by cuttings. Special attention should be paid to the purity of seedlings to ensure the varietal characteristics of the improved variety.

In addition to the above breeding methods, breeders at home and abroad have also adopted mutation breeding through physical and chemical treatments to obtain variations and polyploid breeding using modern bioengineering technology, achieving new progress and opening up new pathways for breeding superior tea varieties.