For many crop plants, a significant factor that contributes to
salinity tolerance is the ability to exclude Na+ from the shoot (Tester
and Davenport, 2003; Møller and Tester, 2007). A similar result was
also observed in this study. In this study, the Na+ distribution pattern
in the cucumber plant grafted onto pumpkin under high salt
stress was observed. A similar result was also obtained on melon
plants grafted onto pumpkin under low salt stress (Edelstein et al.,
2011). Three mechanisms could explain the decrease in the Na+
concentrations in the shoots of plants with pumpkin rootstocks:
(1) Na+ exclusion by pumpkin roots; (2) minimization of Na+ loading
to the xylem or maximization of retrieval before reaching the
scion by pumpkin roots; and (3) Na+ retention within the pumpkin
rootstock.