B.2. SPECIALIZED USES To change plant size and vigor. To repair damaged parts of established plant. To change plant form. Virus indexing.

Transcription

1 NAME OF THE EXPERIMENT: PRACTICE OF VENEER GRAFTING TECHNIQUE IN MANGO PLANT A. GRAFTING Grafting is a horticultural art of an asexual propagation method in which two different plant parts (rootstock and scion) are joined together so that they continue their growth as one plant. To accomplish this, rootstock as the bottom part of a graft that is in contact with the soil, serves as the root, conducting nutrients across the graft junction and into the shoot, and not allowed to produce side shoots. And, scion as the top part of a graft which is short piece of detached shoot containing several dormant buds being propagated and usually the only one allowed to grow. B. USE OF GRAFTING B.1. GENERAL USES To propagate plants whose cuttings are difficult to root. To provide disease resistance to a susceptible but desirable cultivar. To rapidly increase the number of a desirable cultivar. To hasten the reproductive maturity. B.2. SPECIALIZED USES To change plant size and vigor. To repair damaged parts of established plant. To change plant form. Virus indexing. C. GENERAL CONDITIONS FOR SUCCESS C.1. PLANT CONDITIONS C.1.1. COMPATIBILITY The two plants to be united must be compatible. Even though this union is physical, the two plants should be as closely related genetically as possible for success. C.1.2. DIAMETER OF PLANT PARTS The stock diameter must be equal to or larger than the scion diameter. The scion is usually no larger than the size of a regular pencil, but some methods of grafting use larger stocks so that several scions can be grafted onto one stock. Scions are usually derived from healthy one-year-old plants. C.1.3. PHYSIOLOGICAL STATE Grafting is done in wood species and usually using dormant plants. These plants have no leaves (except in the case of evergreens). In some cases, the rootstock may be actively growing, but the scion should not be growing. Page 1 of 5

2 C.1.4. ALIGNMENT OF TISSUES Since grafting is a physical union that depends on healing of the cut surfaces through mitotic division, the cambium tissues of both parts must be properly aligned. They must make contact over as wide an area as possible. If the tissues are not aligned properly, the graft will fail. The graft junction may be tied to keep the alignment in place throughout the healing period. C.2. ENVIRONMENT The worst environmental enemy of a new graft is desiccation. Therefore, a newly made graft should be waterproofed. After tying, grafting wax may be applied over the entire surface. Some operators use plastic or rubber ties instead of wax. Either way, the purposes to prevent desiccation from occurring at the graft junction and also to prevent entrance of disease and decay-causing organisms. C.3. THE OPERATOR In addition to all of the mentioned factors, the operator should always use a sharp knife and make sharp, clean cuts to ensure good contact of tissue. A more experienced operator is likely to have greater success than a novice at grafting. D. METHODS OF GRAFTING Grafting may be accomplished by one of several methods, depending on the species, the age and size of the plant, the problem to be corrected, and the purpose. Although some methods are for general purpose use, others are used to solve specific and specialized problems. Notwithstanding the method, the principles are the same. There are two basic methods for bringing about the union between the two plant parts in a graft: - one in which the scion is detached from its source and transferred onto another plant and a second in which no detaching is done before the formation of the graft union. D.1. APPROACH OR CONTACT GRAFTING Commonly used in carambola, custard apple, guava, litchi and mango. D.2. BARK GRAFTING Commonly used in litchi. D.3. BRIDGE GRAFTING Commonly used in apple, cherry, pear and walnut. D.4. CLEFT OR WEDGE GRAFTING Commonly used in avocado, carambola, cashewnut, citrus, custard apple, durian, grape, hog plum, jackfruit, litchi, mango, mangosteen and rambutan. D.5. EPICOTYL GRAFTING Commonly used in jackfruit. Page 2 of 5

3 D.6. INARCHING GRAFTING Commonly used in apple, cherry, jackfruit, pear and walnut D.7. NOTCH GRAFTING Commonly used in cashewnut and custard apple. D.8. SIDE GRAFTING Commonly used in carambola, citrus, litchi and mango. D.9. STONE GRAFTING Commonly used in mango. D.10. VENEER GRAFTING Commonly used in custard apple, guava, hog plum, mango and sapodilla. D.11. WHIP OR SPLICE GRAFTING Commonly used in custard apple and litchi. D.11. VENEER GRAFTING Veneer literally means a thin surface layer, usually of wood, laid over a base of common material; or any of the thin layers glued together. It is the most common method in Bangladesh. Success can be %. Now-a-days veneer grafting particularly for mango is successfully replaced by the less labour requiring and less time consuming cleft grafting. D BEST TIME FOR VENEER GRAFTING April-August, 1 or 2 months earlier and later not too bad. The worst time is November-January. D SELECTION CRITERIA OF ROOTSTOCK Stock should be raised from heavy mango stones which sown soon after extraction (within 3-4 days). As the seeds are sown in June-July, seedlings become ready for use as rootstocks in next April-July, that is 9-12 months aged. Should be vigorous in growth and strong enough to make the grafting success. The stock diameter must be equal to or larger than the scion diameter. D ACTIVATION OF ROOTSTOCK Seedlings with fully matured leaves are not actively growing and will not be good for grafting. To be successful grafting in our climatic environment, the rootstock must be fully active. This active growing condition in plant is indicated by the presence of young leaves or flushes. To achieve this state, the seedlings must be fertilized with nitrogen and watered liberally (every day for seedlings in container or bags) 3-4 weeks before grafting. Page 3 of 5

4 D SELECTION OF SCION Vigorous and well matured shoots with short internodes apart from about cm of the tip. Scion materials should be derived from 6-12 months old terminal shoot. The scion stick is usually no larger than the size of a regular pencil ( cm in diameter). Healthy, well developed vegetative buds which are about to open should be present at the head of scion. D PREPARATION OF SCION Ideally, it is good to cut off the leaves leaving their petioles from the twigs while attached to the mother plant, 7-10 days prior to using. When the petioles get dried up and drop, it is assumed that the shoot is ready for grafting. This ensures higher rate of success but it is more laborious. Ordinarily, the scions are prepared by About cm long twig is severed from the mother plant. Cut off their leaves close to the stem ensuring that the buds are not damaged. It is made ready by a slanting cut about 4-5 cm long on one side at the base of the scion so that the cut surfaces fit well and thus help early union of the scion with the stock plant. D PREPARATION OF STOCK A slanting cut of 4-5 cm is made on the one side of the stock plant cm from the base. The cut is 3-4 mm in depth by removing the piece of bark with wood. D UNITING STOCK AND SCION The cut surfaces of the rootstock and scion are brought together by holding them in position and tying them with rubber band or polythene strip. The two can be tied together with thread, too. D BAGGING An additional measure may be taken to protect the place of union from exposure to rains and wind, and create a micro-environment congenial to union, by covering the grafted areas and tops of both rootstock and scion with a polythene bag. In another method, the top of the rootstock is not included in the cover. Care is taken that enough vacant space remains inside the bag. D COMPLETION OF THE GRAFTING PROCESS 1n days after grafting operation, the dormant buds in the scion start sprouting. When growth takes start in the scion, the top of the rootstock is cut Page 4 of 5

5 off. The bag is removed in another 3-4 days. Usually, 3-4 weeks are taken for the completion of veneer grafting. It should be remembered that the moisture situation in the soil should be kept as optimum for the normal growth from the grafting operation up to the successful establishment of the scion. Finally, the successful grafts are transplanted in a garden or the yard of a homestead area. E. PRECAUTIONS Scions should be collected from the center portion of the shoots. Too succulent and pithy terminal sections should be discarded. Flower buds should be avoided. F. AFTER CARE Watering to the grafted plants every day for container or bags grown saplings. Fertilize the saplings once every month or two. Protect the saplings from pests and diseases. SUGGESTED BOOKS Horticulture: Principles and Practices By GEORGE ACQUAAH Principles and Practices By HUDSON T. HARTMANN, DALE E. KESTER, FRED T. DAVIES, ROBERT L. GENEVE Concepts and Laboratory Exercises By CAULA A. BEYL ROBERT N. TRIGIANO By ALAN TOOGOOD Training Manual on and Nursery Management By HORTICULTURE RESEARCH & DEVELOPMENT PROJECT IN COLLABORATION WITH DAE AND BADC Plant Nursery Management: Principles and Practices By P. RATHA KRISHNAN, RAJWANT K. KALIA, J.C. TEWARI, M.M. ROY Tropical Nursery Manual A Guide to Starting and Operating a Nursery for Native and Traditional Plants By KIM M. WILKINSON, THOMAS D. LANDIS, DIANE L. HAASE BRIAN F. DALEY, R. KASTEN DUMROESE Page 5 of 5