Effect of different grafting methods on vegetative growth and yield of tomato fruit.

Introduction: Today in order to produce vegetable fruits tolerant to adverse environmental conditions and increase growth, yield and fruit quality, grafting methods have been created. Tomato (Solanum lycopersicum) is one of the most important greenhouse products. Heirloom tomato cultivars lack disease genetic resistance and are particularly susceptible to epidemics in the field. Grafting can be used to unite the soil borne disease resistance and enhanced vigor of hybrid tomato cultivars with the high fruit quality of heirloom cultivars. There are deficiencies in vegetable grafting including skills for grafting operation performance and after the grafting, having enough knowledge to select rootstock, farm management in application of required fertilizers, graft incompatibility, excessive vegetative growth of grafting plant and physiological abnormalities, and fruit quality reduction. For grafting herbaceous plants such as vegetables, depending on the type of plant, plant size, grafting purpose, available equipment, preference and experience of the grafting plant producer and  post-grafting management, different grafting methods have been introduce which is for different species and the used method is completely different. Each method has its own advantages and disadvantages, which are effective in the survival and development of grafting plants. This experiment was conducted in order to evaluate the effect of grafting methods on yield and vegetative growth of tomato plants.   Material and Methods: Three common grafting methods, splice, cleft and approach grafting were evaluated for tomato "SV 8320" cultivar grafted on "Rimac" rootstock. Executive operations were conducted in a completely randomized design with three replications at greenhouse of Lorestan Agriculture Faculty. Plant height, number of auxiliary shoot, number and length of internodes, number of fruit cluster, number of flower in cluster, root fresh and dry weight, number of fruit cluster, number of fruit in cluster, width and diameter of fruit, fruit weight, fruit fresh and dry weight, length of fruit tail, fruit tissue firmness, total soluble solid, pH, diameters of hypocotyl, pre, middle and total yield , ratio of the marketable fruits to second degree fruits, and fruit tissue firmness were recorded. Data was analyzed using SPSS software and  means were compared by Duncan’s multiple range test. Results and Discussion: Grafting method had significantly effect on plant height, number and length of internode, root fresh and dry weight, number of fruit cluster, width and diameter of fruit, fruit weight, fruit fresh and dry weight, length of fruit tail, fruit tissue firmness, pH, pre, middle and total yield, the ratio of the marketable fruits to second degree fruits at 5% of probability level. Vegetative characteristics and yield in grafted plants were higher compared to non-grafted plants. Conclusion: According to results of this experiment using different grafting methods lead to stimulate growth in grafting plants, increasing production and product quality. Changes caused by the rootstock are controlled through water absorption, synthesis and transition of water, minerals and herbal hormones. Signal generation in the rootstocks and transition of them to the scion, causes changes in the physiology and morphology of the grafted plant. Grafting success varied between grafting methods, so that splice grafting is better than other methods. Graft compatibility was shown by the ability of tissue to regenerate and the vessels ability in wound tissues to rejoint together then grow and develop as a vigorous composite plant. Attempts to increase the productivity of grafted plant should be followed by the application of good agricultural practices.