Abstract
A series of experiments were carried out in the field of the Germplasm Center, Fruit Tree Improvement Project (FTIP)-BAU-DH as well as in the laboratories of the Department of Horticulture, Crop Botany and Biochemistry of Bangladesh Agricultural University, Mymensingh, during the year 1999-2000, 2000-2001 and 2001-2002 to investigate into the (i) standardization of different methods of vegetative propagation, (ii) standardization of scion production in mango from clonal hedgerow plantation, (iii) efficacy of epicotyl grafting with different stages of scion and rootstock through anatomical study, (iv) effect of physiological factors of scion and rootstock on the success and growth of the grafts, (v) performance of the plants produced by different methods of vegetative propagation in respect of growth and development, graft union process, shoot-root growth and fruiting behaviour of the plants, (vi) performance of the plants produced by epicotyl grafting with rootstock-scion combination regarding growth and development, graft union process, shoot-root growth and fruiting behaviour of the plants and (vii) the effect of barrier zone on the graft union process. The required rootstock was raised from collected stones as per specification and grown in the field of the GP center. The scion was collected from the selected mother plants of the GP center. All the field experiments were laid out in Randomized Complete Block Design. The differences among different treatments were separated by LSD test. Different methods of vegetative propagation in mango in relation to the efficacy of the method, time, varieties, propagule production, defoliation of scion, post grafting performance and histological changes were standardized. The result revealed that the best time of grafting for modified cleft and veneer was May and July. May was also the best time for air layering with coconut coir as rooting media. Inserted contact grafting took a long period with low success. Scion defoliated 10 days before grafting gave the best results in respect of % success and final survivality. The highest number and quality scion was harvested from clonal hedgerow planted at 1.00 m and 0.75 m apart in the hexagonal planting system with pruning/pinching in February. Epicotyl grafted plants showed the best performance regarding the graft union process and root growth and development but cleft grafted 'Gopalbhog' plants attained the highest canopy 30 months after planting in the field. Early flower initiation and fruiting was recorded in the air-layered and inserted contact grafted plants. August was the best time followed by July for epicotyl grafting having no effect of age of rootstock. Combination of deep green scion with any stages of rootstock was the best for epicotyl grafting having higher success and low mortality. Combinations of the scion of the same cultivar grafted onto the rootstock of the same cultivar performed a rapid graft union process with higher growth and development in epicotyl grafting though 'Gopalbhog' scion grafted onto the rootstock of unknown mango variety (Gootee aam) gave the highest success and survival at 120 days after grafting. 'Amrapali' scion grafted onto the 'Amrapali' rootstock fruited early. Dark green scion with swollen terminal bud for any mango cultivar was the best in respect to bud breaking, growth and development. Anatomical studies revealed that the formation, dissociation, disruption and disappearance of the barrier zone were one of the vital factors for the graft union process in mango.