Effect of grafting on yield and quality of eggplant (Solanum melongena L.)

Eggplants have fruits with different sizes, shapes and colours, according to the cultivar. Skin colour is due to anthocyanins, pigments located in the cell vacuole of fruit skin that belong to phenolic flavonoids, a powerful antioxidants group. Environmental conditions and growing techniques may influence fruits characteristics and their content of phenolic compounds. Grafting is a non chemical alternative for overcoming the effects of intensive and continuous cropping. The rootstocks preferred for eggplant are hybrids of tomato or tomato KVFN. Also species taxonomically close, as Solanum torvum, have been used and showed good vigour, compatibility and resistance to wilt disease. Information on yield and quality of grafted eggplants onto this rootstock is conflicting. Therefore, the aim of this study was to evaluate yield and quality of eggplant cultivars (‘Birgah’, ‘Black Bell’, ‘Black Moon’ and ‘Longo’) grafted or ungrafted onto Solanum torvum. Plants were grown in an unheated plastic greenhouse from October 2009 till May 2010. Grafted plants had lower mortality, while yield and quality of fruits were mostly influenced by cultivars. Differences among tested cultivars in growth characteristics, graft affinity and compatibility, could have caused the variations observed in growth and yield. ‘Longo’ and ‘Black Moon’ were not influenced by grafting, while grafted plants of ‘Birgah’ and ‘Black Bell’ had a higher portion of unmarketable production. Grafting onto Solanum torvum did not change the colour saturation of berries, with the exception of 'Birgah' that, when grafted, produced fruits with a less vivid colour. Also inner tissue browning was not influenced by grafting. Total phenolic content was greater in the ungrafted plants.