Enhancement of salt tolerance in soybean with NaCl pretreatment

Acclimation response to salt stress in soybean (Glycine max: [L.] Merr. cv. Lee) was found in this study. Soybean seedlings were exposed to 0, 34 and 68 mM NaCl for 23 days (pretreatment), thereafter plants were exposed to 0, 68 and 137 mM NaCl until maturity (main treatment). There was no effect of pretreatment on growth, but at 137 mM NaCl, Na+ concentration in leaves of the plants pretreated with 34 mM NaCl was lower than that of plants pretreated with 0 and 68 mM NaCl. Furthermore, the survival rate under 137 mM NaCl improved with the 34 mM NaCl pretreatment. Therefore, it is possible that soybean can acclimate to salt stress by its increased survival rate, without showing any improvement in growth. The regulation of Na+ or Cl- concentration in leaves could be one of the possible factors involved in salt acclimation of soybean.