为探究干旱胁迫对甜菜幼苗生长及生理指标的影响,使用聚乙二醇-6000(Polyethylene glycol-6000,PEG-6000)模拟干旱胁迫,对甜菜品种"KWS1176"进行室内水培实验.设置6个梯度处理:0 g·L-1(CK)、50 g·L-1(5%)、100 g·L-1(10%)、150 g·L-1(15%)、200 g·L-1(20%)和250 g·L-1(25%),研究不同浓度PEG-6000模拟干旱胁迫对甜菜幼苗生物量、丙二醛(Malondi-aldehyde,MDA)、抗氧化酶系活性以及可溶性蛋白的影响.结果表明,由于PEG-6000的浓度按梯度上升,甜菜幼苗长势和叶片干鲜重呈下降趋势;甜菜幼苗叶片及根系的4种抗氧化酶过氧化氢酶(Catalase,CAT)、过氧化物酶(Peroxidase,POD)、超氧化物歧化酶(Superoxide dismutase,SOD)及抗坏血酸过氧化物酶(Ascorbate peroxidase,APX)的活性均呈现先上升的趋势.在PEG-6000浓度达到20%后,4种抗氧化酶活性均开始下降,MDA和可溶性蛋白的含量均呈上升的趋势.因此,当甜菜幼苗受到干旱胁迫时,体内会出现大量的活性氧自由基,需要抗氧化酶系来协助清除.但在高浓度PEG-6000干旱胁迫下,甜菜幼苗体内的抗氧化酶系活性呈显著下降趋势.
In order to explore the effects of drought stress on the growth and physiological indexes of sugar beet seedlings,indoor hydroponics experiments were carried out on sugar beet variety"KWS1176"using polyethylene glycol-6000(PEG-6000)to simulate drought stress.Six gradient treatments were set:0 g L-1(CK),50 g L-1(5%),100 g L-1(10%),150 g L-1(15%),200 g·L-1(20%),250 g·L-1(25%).The effects of different concentrations of PEG-6000 simulated drought stress on the biomass,malondialdehyde(MDA),antioxidant enzyme activities and soluble protein of sugar beet seedlings were studied.The results showed that as the concentration of PEG-6000 increased in a gradient,the growth of sugar beet seedlings and the fresh and dry weight of leaves showed a downward trend;four antioxidant enzymes in leaves and roots of beet seedlings:catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)and ascorbate peroxidase(APX)all showed an upward trend first.After the concentration of PEG-6000 reached 20%,the activities of the four antioxidant enzymes all began to decline,and the contents of MDA and soluble protein all showed an upward trend.Therefore,when the sugar beet seedlings are subjected to drought stress,a large number of reactive oxygen radicals will appear in the body,and antioxidant enzymes are needed to assist in their removal.However,under the drought stress of high con-centration of PEG-6000,the activity of antioxidant enzymes in sugar beet seedlings decreased significantly.