钾肥对苜蓿低温胁迫下抗氧化酶活性的影响

Effects of Potassium Fertilizer on Alfalfa Antioxidant Enzyme Activity Under Low Temperature Stress

为探讨钾肥种类及用量对苜蓿抗寒性的影响,揭示钾肥提高苜蓿抗寒性的抗氧化生理机制,以紫花苜蓿‘北极熊’为材料,采用二因素(钾肥施肥量和种类)随机区组试验设计,分别设置氯化钾、硫酸钾和磷酸二氢钾0、100、200、300 kg K_(2)O·hm^(-2)(纯钾)。越冬前期挖取苜蓿越冬器官模拟低温胁迫处理(4、-10、-20、-30℃),测定苜蓿根颈丙二醛含量和超氧化物歧化酶、过氧化氢酶、过氧化物酶活性。结果表明,在低温冷冻胁迫处理下,3种钾肥处理的苜蓿材料丙二醛含量均较对照降低,且K_(2)SO_(4)处理降低最显著(P<0.05),随着钾肥施用量的增加,丙二醛呈先降低后升高的变化趋势,在200 kg·hm^(-2)K2O处理下,苜蓿根颈丙二醛含量与CK差异最显著(P<0.05);3种钾肥的不同施用量处理的苜蓿材料,在低温胁迫处理下抗氧化酶活性的变化规律与丙二醛相反,K_(2)SO_(4)处理的苜蓿材料,在200 kg·hm^(-2)K_(2)O施用量下,超氧化物歧化酶、过氧化氢酶和过氧化物酶活性最高且均与CK差异显著(P<0.05),说明该处理的苜蓿抗寒性最强。由此表明施用适宜用量的钾肥有利于提高苜蓿根颈在低温胁迫下的抗氧化特性,降低膜脂过氧化程度,提高苜蓿抗寒性,更有利于苜蓿安全越冬。

In order to explore the effects of potassium fertilizer types and dosage on the cold resistance of alfalfa,and to reveal the antioxidant physiological mechanism of potassium fertilizer to improve the cold resistance of alfalfa,‘Gibraltar’alfalfa was as the material,and a two-factor(potassium fertilizer application amount and type)randomized block experiment was designed,which 3 types of potash fertilizers(potassium chloride,potassium sulfate and potassium dihydrogen phosphate)were used and the applying amounts were set according to 0,100,200,300 kg K2O·hm^(-2).The overwintering organs of alfalfa were excavated to simulate low temperature stress treatment(4,-10,-20 and-30℃)in the early stage of overwintering,and the content of malondialdehyde(MDA),superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)activity in the root crown of alfalfa were determined.The results showed that,under the low temperature freezing stress treatment,the MDA contents of alfalfa treated with 3 kinds of potassium fertilizers were lower than that of the control,and the decreased range of K_(2)SO_(4) treatment was the most significantly(P<0.05).With the increase of potassium fertilizer application,MDA decreased first and then increased.Under the treatment of 200 kg K_(2)O·hm^(-2),the difference between MDA content and CK in root crown of alfalfa was the most significant(P<0.05).The changes of antioxidant enzyme activities in the alfalfa materials treated with different application rates of the 3 potassium fertilizers were opposite to those of MDA under low temperature stress treatment.The activity of SOD,POD and CAT were the highest and both had the most significant difference with CK(P<0.05).It showed that the alfalfa treated with K_(2)SO_(4) in autumn and the application rate of 200 kg K_(2)O·hm^(-2)had the strongest cold resistance.The results showed that potassium fertilizer with appropriate dosage could improve the antioxidant properties of alfalfa root and neck under low temperature stress,reduce the degree of membrane lipid peroxidation,improve the cold resistance of alfalfa,and be more conducive to the safe overwintering of alfalfa.