P., SAMPATH KUMART. R., GURUPRASADPORIKA, HARIKANTHJ., SATISHAK. K., UPRETIS., MOHAN KUMAR2021-02-082021-02-082018-08UHS14PGD99https://krishikosh.egranth.ac.in/handle/1/5810160997Grape is an important commercial fruit crop of India. The rootstocks gain significance in grape cultivation to address issues related to both biotic and abiotic stresses. When rootstocks were employed, the aspect of compatibility plays an important role. Improvement in berry quality is also one of the major important issues considering the export as well as consumer preference. Experiments in the thesis entitled “Studies on graft compatibility and improvement of fruit quality in coloured grape cvs. Red Globe and Crimson Seedless” were carried out at ICAR-Indian Institute of Horticultural Research, Hesaraghatta, Bengaluru during the period 2015-17 to address the issues related to graft compatibility of grape rootstocks in coloured grape cultivars and improvements in their quality using growth regulating chemicals. From the investigations, it was observed that the compatible rootstocks along with scion treatments improved graft success to overcome the delayed graft incompatibility. The characterization and selection of rootstocks before grafting on the basis of morpho-physiological, histological and biochemical studies helped in identifying the efficient marker(s) for graft success and in revealing the factors deciding better growth and production in commercially important grape cultivars. On the basis of findings from first experiment, it was observed that scion cultivars „Red Globe‟ and „Crimson Seedless‟ on „110R‟ and „66/4‟ were significantly superior over the other rootstocks, in terms of better graft success and compatibility. However, keeping in view the importance of „Dogridge‟ rootstock in overcoming the abiotic stresses viz., salinity and water scarcity, the second experiment resulted in overcoming the problem of delayed incompatibility of Red Globe grafted on it. Graft union is a key factor in successful graft take and subsequent performance of grafted seedlings. The obtained result from scanning electron microscope helps in identifying the best combination of stock-scion through callus development. The outcome of this study revealed that, pre-conditioning as well as treating of scions with 100 ppm BAP would overcome the problem of delayed incompatibility and improved the graft success when Dogridge was employed as a rootstock. Uniform berry colour and bunch compactness can be manipulated by good viticultural practices. In the third experiment, removal of basal leaves at veraison stage followed by berry thinning and dipping of bunches in 500 ppm ethrel solution resulted in reduced cluster compactness and in production of bold berries, attractive bunch shape and uniform colour. Hence, such practices would help the growers to fetch good economic returns by producing quality and uniform coloured grapes. Thus good viticultural practices like use of appropriate rootstocks and canopy practices are important for producing quality grapes in coloured cultivars.EnglishThesis