Response of plant yield and leaf pigments to saline conditions: Effectiveness of different rootstocks in melon plants (Cucumis melo L.)

Two varieties of Cucumis melo (Resisto and Arava) were grafted onto three hybrids of Cucurbita maxima and Cucurbita moschata cultivars (Shintoza, RS-841 and Kamel). Ungrafted Cucumis melo var. Resisto and var. Arava plants were used as controls. Plants mere grown under controlled greenhouse conditions and were constantly fertilized with macro-and micronutrients, supplied with irrigation water rich in Na+ and Cl-. Contents of chlorophylls a and b, carotene pigments, Cl- and total and soluble Na+ and K+ ions were measured in all the scion parts of the plants. The results showed that grafted plants exhibited differences in the leaf content of Naf and especially Cl- in comparison with ungrafted plants. In addition, yield as well as leaf pigments appeared to be good indicators of Cl- levels in scion parts. It is assumed that grafted plants developed various mechanisms to avoid physiological damage caused by the excessive accumulation of these ions in leaf, including the exclusion of Cl- ion and/or decrease in Cl- absorption by the roots and the replacement or substitution of total K+ by total Na+ in the foliar parts.