Physiological and biochemical characteristics of Jatropha curcas seedlings under osmotic stress

Key words: 
• forest biology /
• osmotic stress /
• physiological and biochemical characteristics /
• correlation analysis /
• drought resistance /
• Jatropha curcas

Abstract: To reveal the effects of drought and water shortage on physiological and biochemical characteristics of Jatropha curcas seedlings，osmotic stress treatments （0，5%，10%，15%，20%，and 30% concentrations of PEG 6000） were applied. Also Duncans multiple comparisons and a correlation analysis were carried out. Results showed that with prolonged stress （up to 10 d），the leaf relative water contents（RWC） with the 15%，20%，and 30% osmotic treatments decreased significantly（P＜0.01）. For all treatments，soluble protein and chlorophyll，O2- production rate，and protective enzymes super- oxide dismutase（SOD），glutathione reductase（GR），and catalase（CAT） increased then decreased. Compared to the control，Malondialdehyde（MDA） content for the 15% osmotic treatment up to 10 d，significantly increased（P＜0.01）. A correlation analysis showed significant negative correlations between RWC and 1） MDA（r = -0.483，P＜0.05），2） SOD （r = -0.464，P＜0.05），and 3） GR （r = -0.453，P＜0.05）；whereas significant positive（P＜0.05） correlations were found between soluble protein content and the protective enzyme activities and chlorophyll（chl） The O2- production rate and MDA were significantly and positively （P＜0.01） correlated with SOD or GR activities；while the protective enzymes system activities had significant positive（P＜0.01） correlations with chl. Thus，J. curcas seedlings resisted drought stress by increasing the protective enzyme activities which increased its tolerance to osmotic stress. ［Ch，3 fig. 1 tab. 27 ref.］