SALINITY TOLERANCE OF GRAFTED WATERMELON SEEDLINGS

In order to evaluate the salinity tolerance of grafted watermelon, two sets of experiments were conducted in a growing chamber where 'Esmeralda' varieties were grafted onto interspecific squash (Cucurbita maxima Duch. x Cucurbita moschata Duch.) and Lagenaria siceraria rootstocks. Both non-grafted and self-garfted plants were used for control. For salt stress, 2.85 and 4.28 mM/l substrate doses of NaCl were added with each irrigation in 2 day intervals for a duration of 23 days. Interspecific-grafted plants showed the highest salinity tolerance as plant biomass and leaf area were not decreased but improved by salinity in most cases. Furthermore, transpiration and photosynthesis activity did not decrease as much as it did in the case of other grafting combinations. Interspecific and Lagenaria rootstocks showed sodium retention, as elevation of Na+ content in the leaves of these grafting combinations was negligible compared to self-grafted and non-grafted ones. Presumably abiotic stress tolerance can be enhanced by grafting per se considering measured parameters of self-grafted plants did not decrease as much as seen in non-grafted ones.