PHOTOSYNTHETICA

Photosynthetica 2012, 50(2):180-188 | DOI: 10.1007/s11099-012-0002-1

Improving melon and cucumber photosynthetic activity, mineral composition, and growth performance under salinity stress by grafting onto Cucurbita hybrid rootstocks

Y. Rouphael¹, M. Cardarelli², E. Rea³, G. Colla^2,*

¹ Department of Crop Production, Faculty of Agricultural Engineering and Veterinary Medicine, Lebanese University, Dekwaneh, Beirut, Lebanon

² Department of Agriculture, Forests, Nature and Energy (DAFNE), University of Tuscia, Viterbo, Italy

³ Agricultural Research Council - Research Centre for the Soil-Plant System, Roma, Italy

The aim of the current work was to determine whether grafting could improve salinity tolerance of melon and cucumber, and whether possible induction of tolerance to salt stress was associated with the protection of the photosynthetic apparatus. Two greenhouse experiments were carried out to determine gas exchange, mineral composition, growth and yield of melon (Cucumis melo L. cv. Cyrano) and cucumber (Cucumis sativus L. cv. Akito) plants, either ungrafted or grafted onto the Cucurbita hybrid rootstocks (Cucurbita maxima Duch. × Cucurbita moschata Duch.), 'P360', and 'PS1313', respectively. Plants were grown hydroponically and supplied with two nutrient solutions - a nonsalinized control and a salinized solution which contained 40 mmol L^-1 of NaCl. Salinity induced a smaller decrease in leaf area index (LAI), in grafted-compared to ungrafted plants. Similarly, the P _N and g _s reduction in NaCl treatment compared to control were significantly lower in grafted plants (34% and 34%, respectively, for melon and 14% and 15.5%, respectively, for cucumber) compared to ungrafted plants (42% and 40%, respectively, for melon and 30% and 21%, respectively, for cucumber). In all grafting combinations, negative correlations were recorded between Na⁺ and Cl^- in the leaf tissue and P _N. Grafting reduced concentrations of sodium, but not chloride, in leaves. Under saline conditions a smaller reduction in melon and cucumber shoot biomass dry mass and fruit yield were recorded, with positive correlations between shoot biomass, yield and P _N. These results suggest that the use of salt tolerant Cucurbita rootstock can improve melon and cucumber photosynthetic capacity under salt stress and consequently crop performance.

Additional key words: Cucumis melo; Cucumis sativus; Cucurbita maxima × Cucurbita moschata; grafting; net photosynthetic rate; salinity

Received: August 10, 2011; Accepted: November 9, 2011; Published: June 1, 2012  Show citation