Enhancement of salt tolerance in watermelon using grafting

Abstract

Pots experiment was conducted in the experimental farm of Agricultural Botany Department, Faculty of Agriculture, Ain Shams Univ. during the seasons of 2015 and 2016 to investigate the effect of grafting on salt tolerance of watermelon plants. Watermelon (Citrullus lanatus, Hybrid F1) Aswan1 was grafted onto the rootstock of Flexifort pumpkin (Cucurbita maxima x C. moschata) and irrigated with four different concentrations of NaCl (0.0, 2000, 4000, 6000 ppm). Two samples were taken at 20 and 40 days after planting (DAP). Plant height, leaf numbers and area, branches number, root length, and shoot and root fresh and dry weights were negitavly affected by salinity in ungrafted plants and this effect was directly proportional to NaCl concentrations. On the contrary, grafting positively affected the aforementioned parameters and minimized the harmful effect of salinity. Furthermore, grafted plants showed higher growth vigor comparing with ungrafted control plants or plants received the same treatment of NaCl and these effects were mostly siginificant. An increase in membrane permeability (MP) was detected at 20 and 40 DAP by application of different levels of NaCl salinity and this effect was positively correlated with NaCl concentration. Grafted plants showed decreasing in MP with 12.7% higher LRWC than ungrafted plants. Under 2000, 4000, 6000 NaCl ppm salinity levels, the values of salt injury index recorded 15.1, 26.5 and 37.5 in ungrafted plants at 20 DAP comparing with 0.0, 6.9 and 12.9 in grafted ones.