Influence of selected rootstock on growth parameters, accumulation of IAA and vitamins in scions of Cucumis sativus L. and Cucumis melo L.

Grafting with resistant rootstocks is one of the most effective methods to prevent soil-borne diseases, and it can influence vegetative growth, flowering, maturation periods, and fruit quality, thereby ensuring high yields. In this study, four species from the family Cucurbitaceae were tested as potential candidates for grafting cucumber and melon: Cucurbita ficifolia Bouché, Cucurbita moschata L., Cucurbita pepo L. and Cucurbita maxima Duch. The study focused on the grafting methods that optimize growth parameters and the accumulation of hormones and vitamins in rootstock. The results indicated that Cucurbita maxima Duch. is the most suitable rootstock material for grafting to Cucumis sativus L. and Cucumis melo L., as it exhibited superior plant and root mass. Among the two grafting methods tested, the tongue approach ('X') demonstrated the best results in terms of growth parameters and the accumulation of indole-3-acetic acid (IAA) and vitamins in the scion leaves. IAA and vitamin concentrations were measured using HPLC in grafted samples at 2, 4 and 6 weeks of age. In the 'X' method, IAA accumulation from the end of the second week was twice as high compared to control plants. This method also showed higher vitamin content, with increased levels of B vitamins and vitamin C at the end of the 4th week (25.2-135.1 and 52.3-67.0 %, respectively), and vitamins A, E, D3 , K starting from the 2nd week (1.5-2 times higher). Conversely, the insertion or slant cut grafting method ('Y') did not show any significant increase in the analyzed parameters and was comparable to the control. The 'X' method for grafting both Cucumis sativus L. and Cucumis melo L. onto Cucurbita maxima Duch. plants demonstrated the best results and is recommended for production.