A tea clone is selected on the basis of long term trial for its superior characteristics, useful for commercial tea production and is subsequently allowed to grow as the mother plant for vegetative propagation. The mother bushes of a particular clone are maintained in the nucleus plot for taking cuttings. The location of the nucleus plot should be in a convenient place subject to constant supervision. The soil of the area should be fertile and well drained. One nucleus plot has to be built up for each clone to be used in the estate. The number of mother bushes in a nucleus plot will, therefore, depend on the area planned to be planted with a particular clone. In general, the expected number of good, healthy cuttings from a mother bush may vary from 30 to 300 per year. Thus to supply sufficient planting materials for one hectare area, a minimum number of about 250 bushes of a clone giving on an average 100 cuttings a year will have to be raised in a nucleus plot.
The nucleus bushes should not be grown under shade.
Cultural Operations in Nucleus Plot
The nucleus plot demands constant supervision and maintenance for giving good results. The mother bushes should be manured with balanced NPK mixture. During the dry season, the area may be mulched well and irrigated regularly. The nucleus plot should not be shaded, excepting initial one or two year period. Temporary shade may be used during that period.
The mother bushes are pruned of skiffed twice a year in N.E.India. They should be clean pruned at least once a year, which is generally done after the autumn propagation in September-October. At the time of pruning all weak and banjhi branches should be removed. After that, new shoots are allowed to grow freely till the time of spring propagation. Spring propagation is generally carried out in April- May after which the mother bushes should preferably be deep skiffed leaving about 8 to 10cm of new wood.