The 2010 ASHS Annual Conference

Grafting technology is considered a unique component in sustainable vegetable production. In addition to managing soil-borne diseases, grafting with interspecific rootstocks is suggested to improve yield in tomato (Solanum lycopersicum) production due to enhanced nutrient uptake. Four interspecific tomato rootstocks including 'Beaufort', 'Maxifort', 'Multifort', and 'RST-04-105' were evaluated in a greenhouse study using the determinate tomato cultivar Florida 47 as scion in the absence of soil-borne pathogens. Non-grafted and self-grafted 'Florida 47' were used as controls. Essential nutrients were delivered by a regulated Dosatron fertigation system to tomato plants grown in pots filled with horticultural grade perlite. The results showed that all the rootstocks significantly increased the total and marketable yield of ‘Florida 47’ compared to non-grafted and self-grafted controls. The marketable yield improvement by 'Beaufort', 'Maxifort' and 'Multifort' was attributed to larger number of fruit per plant, while higher average fruit weight was the contributing factor in tomatoes grafted onto 'RST-04-105'. Self-grafting of 'Florida 47' resulted in similar yield as non-grafted control. Plant tissue analysis indicated the overall enhancement of nutrient absorption as a result of grafting with rootstocks. At the first harvest, total above ground accumulations of N, K, and Ca were significantly higher in the grafted treatments in contrast to the non-grafted and self-grafted controls. Self-grafting did not cause significant changes in plant nutrient contents. The elevated levels of nutrients by using rootstocks were largely related to increased biomass accumulation rather than higher nutrient concentration (on a dry weight basis). Interestingly, the leaf concentration of P was significantly lower in the grafted treatments. The enhanced uptake of Ca was consistent with reduced incidence of blossom end rot in tomato plants grafted onto rootstocks. At the final harvest, the grafted treatment with 'Maxifort' maintained significantly higher contents of N, K, and Ca, while grafted plants with other rootstocks did not differ from the non-grafted control. The potential of interspecific rootstocks for enhancing nutrient uptake and improving tomato yield needs to be further investigated in the field trials in order to provide appropriate recommendations for fertility programs of grafted tomato production.