Breeding of Fruit and Plantation Crops

Clonal selection

• Exploitation of heterogenity in seedling population, arising out of cross pollination, through clonal selection has played a vital role in tea improvement programme.


• Selection of elite mother bushes is an important step in the development of its clones. (Mother bushes are selected based on visual assessment of characters like large pluck size and higher unit weight, higher density of plucking points, semi-orthotropic branching, and healthy and robust branching. Quality of made tea such as light green leaves and pubescence of leaves and branches are also looked into. The yield potential of mother bushes is calculated based on bush yield/unit area, out of field yield / unit area. Yield over two pruning cycles are considered and yield potential of more than one is considered high yielding. Subsequent processes in the development of clones involve the assessment of rooting performance in the nursery, establishment in the field and survival in succeeding drought period, yielding ability, quality of tea and tolerance to biotic and abiotic stresses. Then select the best performing clones.


• These are then tested in different tea-growing areas. Based on com¬prehensive assessment, clones are released for commercial planting. The whole process from time of selection of mother bushes to release of clones for commercial cultiva¬tion takes about 10-12 years. The long time required for release of a clone is the limitation and methods for early yield prediction of clones are necessary. However, clonal selection has resulted in the development of several superior clones for commercial use in different tea growing regions. Twenty-eight clones have been developed by United Planters Association of South India.


• Development of Seed Stock: Use of monoclones or few clones, is 'hazardous due to narrow genetic base and susceptibility to pests and diseases. Seed stocks are hence developed to widen the genetic base. (For development of seed stocks, elite clones are selected and planted in a specific statistical design in an isolated area, natural cross-pollination is allowed and seeds are collected. Seeds obtained from crosses involving more than 2 clones are referred to as polyclonal seeds, while that resulting from 2 clones are called biclonal seeds. In view of the comparatively greater phenotypic uniformity in progeny, biclonal seeds are preferred to polyclonal seeds. Now clonal selection is done in biclonal progenies.


• Interspecific Hybridization: In general, progeny of inter¬specific and wide crosses is usually vigorous but lacks quality and morphological uniformity. A highly produc¬tive clone, TV 24, has been developed by producing F; hybrid between C. irrawadiensis x C. assamica, and crossing this with Assam-China hybrid (TV 2). Induced polyploids in tea are vigorous and show resistance to environmental stresses. They are not grown commercially owing to poor quality


Clones developed by United Planters’ Association of South India (UPASI)

Clone	Number	Character
UPASI (Evergreen)	1	Hardy
UPASI (Jayaram)	2	Hardy, high yielding
UPASI (Sundaram)	3	High-yield
UPASI (Brook lands)	6	Hardy
UPASI (Golconda)	8	High-yielding
UPASI (Athrey)	9	High-yielding
UPASI (Pandian)	10	Hardy, suited for windy areas
UPASI (Singara)	14	High quality
UPASI (Spring field)	15	High quality suited for windy areas
UPASI (Swarna)	17	High-yielding
UPASI	24	Hardy
UPASI	25	High-yielding
UPASI	26	Hardy
UPASI	27	High-yielding
UPASI (UPASI 10 x TRI 2025)	28	Biclonal, 6,120kg made tea/ha, good strength