EFFECTS OF NACL AND ISO-OSMOTIC PEG STRESS ON THE GROWTH AND OSMOTIC COMPONENTS OF CUCUMBER SEEDLING

Abstract

The effect of NaCl and iso-osmotic PEG stress on the growth and osmotic components in Jinchun No. 2 (Cucumis sativus L.) was investigated. The results showed that both NaCl and iso-osmotic PEG stress significantly decreased dry weights of root, stem and leaf, as well as leaf area. Plant growth was more affected by iso-osmotic PEG than NaCl treatment. Both NaCl and iso-osmotic PEG stress significantly decreased leaf relative water content (RWC), but there was no significant difference in leaf RWC between NaCl and corresponding iso-osmotic PEG treatment. The main change of osmotic components was the increase in Na + and Cl - under NaCl stress, but the substances that obviously increased were proline and soluble sugar under iso-osmotic PEG stress. Compared with the uptake of inorganic ions, plants should cost a higher energy to synthesize organic solutes for osmotic balance, which seems to result in a growth penalty. Taken together, these results suggested that mainly an osmotic effect occurs in the short time NaCl stress. In addition, the sensitivity was different between NaCl and iso-osmotic PEG treated plants, which could attribute to the different osmotic components under stress.