Effects of Exogenous Spermidine on Growth,Stress Resistance Physiological Characteristics of Potato Seedlings under Salt Stress
In order to explore the physiological regulatory mechanism of spermidine(Spd)enhancing salt tolerance in potato seedlings and understand the differences in response of different salt tolerant potato va-rieties to Spd,The experiment adopted nutrient solution culture method to simulate different salt stress levels with 100,200,300 mmol/L NaCl solutions.And the medium salt-tolerant variety'Jinshu 16'and the mild salt-tolerant variety'Jizhangshu 12'were used as test materials.When the virus-free potato seed-lings reach 4-5 true leaves,continuous foliar spraying of 0.9 mmol/L exogenous Spd was applied for 7 days,2 times per day.The effects of exogenous Spd on the growth of potato seedlings,the activities of an-tioxidant enzymes and the contents of osmotic regulatory substances in leaves were analyzed.The results showed that:Leaf spraying Spd alleviated the inhibitory effect of salt stress on seedling growth,increased chlorophyll content and root activity,and increased the activities of antioxidant enzymes such as superox-ide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX),contents of ascorbate(ASA)and glutathione(GSH),and proline,soluble sugar,amino acid contents.Under 200 mmol/L NaCl stress,Spd had the most significant alleviating effect on'Jinshu 16'.Studies had shown that Spd could improve the adaptability of potato seedlings to salt stress and promote the growth of potato seedlings by improving the its root vitality,chlorophyll content,antioxidant enzyme activities and osmotic regulation ability.
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