Vegetative Propagation in Tea is at present adopted by all tea producing countries and Tea Estates.
Tea was propagated only through seeds until the middle of the last century. The possibility of raising tea plants from single-node cuttings as an economic method of propagation was first reported by A.C. Tunstall in 1931. Thereafter with the standardization of the technique in 1949, the first set of clones was released to the industry. Since then vegetative propagation has successfully been employed for multiplication of tea.
In tea, for vegetative propagation, an intermodal cutting from the primary bearing a healthy mother leaf with a swollen dormant axillary bud is essential. Adventitious roots on the basal cut end are initiated from the cambium layer through a process of asexual cell division called mitosis. In mitosis, the newly divided daughter cells also contain the same number of chromosomes as the mother cell. Therefore, in vegetative propagation, all the traits of mother bush are transferred to the offspring.
Time of vegetative Propagation in Tea
There are two peak periods of vegetative propagation for plains of N.E. India where the rate of success is very high. They are
Period I – ( Spring ) – Mid april to early June
Period II – ( Autumn ) – Mid September to Mid November
Extended Period of propagation beyond these periods may give more number of cuttings but will produce less number of plantable plants. Therefore, for good success in vegetative propagation, it is important to adhere to the above periods.
Treatment of Mother Bushes
The mother bushes should be cleaned pruned once a year preferably in the cold weather immediately after the autumn propagation is over. Once the spring propagation is over, instead of pruning, it is advisable to deep skiff the mother bushes retaining 10-12 cm of new wood. To obtain good quality cuttings, it is important to remove all the thin “ Bhanjhi” shoots, weak branches, and dead/diseased branches by a round of good knife cleaning at the time of pruning / deep skiffing. The mother bushes should not be allowed to grow under any stress conditions arising out of moisture deficits, pests, disease, weed competition, and inadequate nutrition. It is very important to protect all the newly opened buds/shoots from sucking pests from the beginning by taking appropriate action on time.
The mother bushes should be manured with YTD 2:1:2 mixture@150kg N/ Ha in two equal splits. The 1st split should be applied on the fully moist clean ground in early spring and the 2nd split in June/July after the spring propagation is over.
Nursery Site for vegetative propagation in tea
The nursery should be located conveniently for easy supervision on well-drained high land near a perennial source of water.
Type Of Soil
The soil should neither be too clayey nor too sandy and should be working to a good tilth. Sandy loam soils rich in organic matter are most suitable. In the case of clayey soils, depending upon their degree of heaviness, inert river sand/or self decomposed powdered cattle manure in various proportions ( 1:2,1:3,1:4, etc) should be mixed thoroughly to obtain a homogeneous mixture. The soils used for nursery should be within the pH range of 4.5 to 5.0 and should be free from harmful eelworm.
Preparation Of Nursery Beds for vegetative propagation in tea
Prepare the beds at least 4-6 weeks before planting cuttings placed along east-west direction. The best time of bed preparation is between February and April for spring and autumn propagation, respectively. The width of the beds should be 1.5 m with any convenient length. A good drainage system is one of the important keys to success in the nursery. Therefore in between two beds 45 cm wide and 60 cm, deep straight drains must be provided at the time of preparation of beds. these drains should be connected to a suitable outlet nearby. It is also important to make the surface of each bed slightly cambered for a quick runoff of rainwater.
For rooting beds the soil should be worked to a fine tilth and incorporate SSP@50g/m2 to a depth of 15 cm. the soil should be adequately compacted by running a 60 cm wide 90 cm dia concrete hollow cylindrical roller on the surface of the beds several times. Nursery beds which will be kept for autumn propagation should be watered and treated by a round of oxyfluorfen @ 500ml/200 l of water using a clean spraying machine. Thereafter cover the beds with a layer of thatch or any leafy material.
The soil used for filling up polythene sleeves should be kept under the shade and sieved twice through G1 wire mesh No. 4 to remove all undecomposed vegetative matter as well as to obtain a fine tilth. For good root development, it is necessary to mix SSP@500g/cubic meter of the soil before filling up of polythene sleeves. It has been found that for all-round development of sleeves grown clonal plants, the sleeve should be 15-17.7 cm lay flat, 20-25 cm is long, and 150 gauge thick. The sleeves should be filled up at least 4-6 weeks before planting of cutting and should be kept under the overhead shade and watered regularly. If some sleeves are set aside for autumn propagation then they should be treated with a round of oxyfluorfen and covered by a layer of thatch / kept under overhead shade.
The overhead shade should be either slanting opening towards the north and sloping towards south or flat depending upon the material used. The height should be such that the free movement of workers under the shade is not difficult.
Quality Of cuttings
To a great extent, the success of vegetative propagation depends upon the quality of cuttings used. As far as possible, cuttings should be obtained from hard/semihard, green, middle parts of freely growing primaries.
Each cutting should contain one healthy mother leaf and a swollen/dormant axillary bud. Hard brown cuttings and cuttings with overgrown axillary buds must be discarded as these cuttings tend to form large callus growth and remain dormant for a long period.
Preparation of cuttings
While making cutting, the top cut should be made immediately above the axillary bud parallel to the leaf blade. The basal cut should be given at least 2.5 cm below the petiole of the mother leaf obliquely more or less parallel to the top cut. The cuts should be clean and sharp without any jagged ends.
Cuttings should always be prepared under shade in a bucket containing 0.1% Zinc sulfate solution ( 100 gm in 100 lit of water) and planted immediately. Prepared cuttings should not be stored for a long time. In case if there is some delay between making cuttings and planting, then the prepared cutting should be kept in a cool dark place wrapped in clean wet hessian cloth. At the time of planting of such cuttings, the basal cuts should be freshened using a sharp blade / Knife.
Planting Of cuttings
For best results, cuttings should be planted during the cooler parts of the day. Direct sunlight at the time of planting should be avoided. The cuttings should be planted in the same direction pointing the tip of the mother leaves to north or west in order to preclude possible sun scorch damage. At least 24 hours before planting cuttings if there is no rain, the beds/ sleeves should be watered properly. Plant the cuttings keeping the axillary buds and the petiole of the mother leaf at least 4-5mm above the soil surface and the mother leaf in an upright position. Following planting cuttings, press the base of the cuttings with the forefinger and thumb firmly to avoid air pockets.
Lightly water the cuttings immediately the following planting using clean hand sprayer fitted with cone/ fan nozzle. Do not allow the beds to go dry and continue watering using hand sprayers as and when required. At this stage, the water requirement of cuttings is very low hence over-watering must be avoided.
Use of Fertilizers
Initially, unless there is root initiation the newly planted cuttings do not require any fertilizer. However, as the cuttings grow, the demand for nutrients is also increased. Under such a situation after the plants produce 4-5 full leaves, they should be manured with a mixture of NPK ( 2:1:2) and dry soil at a 1:9 ratio around the collar of the plants. The manuring should be done for 6-8 rounds at a 4-week interval.
Pest and Disease control
The most common pests in the nursery are a red spider, purple mite, Greenfly, and Cricket. Pest Infestation should be monitored regularly and appropriate action should be taken timely to avoid damage.
Blister blight and collar rots of mother leaves are the two most common diseases of clonal nurseries. overcast sky with misty climate during May-July is two main predisposing factors for blister blight infection. Once the blisters appear on young leaves, then any approved COC formulation should be sprayed at 1:400 dilution at 4 days interval until the weather becomes warm and sunny.
Collar rot of mother leaves normally occurs in July where the propagation period is extended. Once this disease is noticed, two rounds of COC at 1:400 dilution on the cuttings are recommended at 10 days interval.
Hand weeding from the beds as well as sleeve surfaces should be carried out as a routine practice. Mossy growth as and when noticed should be scraped using a small piece of a bamboo stick. Impeded drainage and over watering are two main causes for the growth of moss. Therefore improvement of drainage should receive priority.
In the rainy season dripping water from the overhead shade makes large depressions on the soil surface. At times the cuttings are dug out causing huge damage. The drip damaged sleeves should be topped up regularly using fine dry soil. The overhead shade should be adjusted frequently to eliminate the cause of drip damage.
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