Evaluation the efficiency of Citrullus colocynthis and Cucumis metuliferus as ‎rootstocks for cucumber to increase the salinity resistance compared to the ‎commercial rootstock of Cobalt

Water and soil salinity is one of the reasons for the reduction of cucumber yield. In order to verify the feasibility of using two non-commercial rootstocks to increase salinity resistance in cucumber and compare it with the commercial rootstock of Cobalt RZ F1, an experiment was conducted in the research farm of agricultural faculty of Arak University in a factorial experiment based on randomized complete block design. The first factor was salinity stress at three levels (no stress, 30 mM and 60 mM NaCl) and the second factor was rootstocks at four levels included non-grafted cucumber, colocynth (Citrullus colocynthis), kiwano (Cucumis metuliferus) and Cobalt (C. maxima×C. moschata). The results showed that increasing the amount of salinity led to a significant decrease in the stem length, stem, leaf and fruit dry weight percentage. The Cobalt rootstock had the highest stem length, the highest length to fruit width ratio and the lowest increase in malondialdehyde content under salinity stress. The colocynth rootstock had better performance in terms of dry weight percentage of stem, total leaf chlorophyll, leaf carotenoid, relative leaf water content and reduction of leaf sodium content in saline conditions compared to other rootstocks and non-grafted cucumber. The highest amounts of total phenol content, leaf potassium content and percentage of leaf and fruit dry weight were observed in grafted cucumber on kiwano rootstock. The results showed that colocynth and kiwano rootstocks can be introduced as suitable and compatible rootstocks to increase salinity tolerance in grafted cucumbers.