Cross adaptation tolerance in rice seedlings exposed to PEG induced salinity and drought stress

Abstract

The present study investigated the effects of polyethylene glycol (PEG) on rice (Oryza sative L.) seedlings for physiological and biochemical response exposed to subsequent salinity or polyethylene glycol and NaCl (as drought) stress. Salinity or drought induced stress decreased growth-significantly (p<0.05) reduced pigment content, stomatal conduction (gs), transpiration (E) and net photosynthetic rate (Pn), whereas no significant change in intercellular CO2 concentration (Ci) was recorded relative to controls. NaCl+PEG stress also reduced POD activity. MDA content and total soluble sugar content increased significantly (p<0.05) under NaCl or NaCl+PEG induced stress. Chlorophyll fluorescence decreased significantly in NaCl-treated plants. However, positive effects were observed in PEG pre-treated (PEG-NaCl, PEG-NaCl+PEG) rice seedlings than NaCl or NaCl+PEG-treated ones. PEG pre-treatment promoted rice seedlings growth and regulation capacity in rice seedlings tolerance to NaCl or drought stress by increase in plant biomass, chlorophyll contents, chlorophyll fluorescence, photosynthetic parameters and antioxidative enzymes activities. The positive effects to the pre-treatment of rice seedlings suggested that cross-adaptation of PEG pre-treatment mediated protection of salinity and drought stress.