Comparison of inorganic solute accumulation in shoots, radicles and cotyledons of Vicia cracca during the seedling stage under NaCl stress

Abstract

In the present study, differences in inorganic solute accumulation in shoots, radicles and cotyledons during the seedling stage of Vicia cracca Linn were evaluated in response to a range of sodium chloride (NaCl) concentrations. Seeds were sown in Petri dishes, germinated and grown with NaCl treatment for 10 days in a growth chamber, with a temperature of 20°C and a 12 h light/dark cycle. Results showed that percentage germination, germination rate, fresh weight and dry weight, and relative water content decreased as the NaCl concentration increased in shoots, radicles and cotyledons. There were no significant differences in dry weight/fresh weight ratios in shoots and radicles among treatments. However, the dry weight/fresh weight ratio in cotyledons was significantly higher at 200 mM NaCl compared to treatments with lower NaCl concentrations. Sodium+ and Cl− concentrations in shoots and radicles increased as the NaCl concentration increased. Sodium+ and Cl− concentrations in shoots and radicles were much higher than those in cotyledons. Similar trends were found for K+, Ca2+, Mg2+, . By contrast, concentrations were lower in shoots and radicles than in cotyledons, while concentrations were similar in shoots, radicles and cotyledons. In particular, K+ efflux was observed in shoots, radicles and cotyledons when no salt stress was imposed. In summary, increased NaCl concentration had adverse effects on germination and post-germination growth. Inorganic ion accumulation in shoots and radicles was high, which might function in osmotic adjustment in those plant organs. By contrast, inorganic ion accumulation did not occur in cotyledons, suggesting that in cotyledons osmotic adjustment might not function the same way as in shoots and radicles, because cotyledons function mainly as storage for carbohydrates or inorganic ions.