土壤中汞胁迫对牧草生理生化的影响

The influence of mercury in the soil stress on physiological characteristics of forage

研究紫花苜蓿、披碱草、高羊茅三种牧草,在10个浓度梯度汞胁迫条件下发芽率、植株高度、过氧化物酶与过氧化氢酶活性、丙二醛与脯氨酸含量、可溶性蛋白及可溶性糖含量生理生化指标的变化情况。旨在探索土壤中汞对牧草的影响机理,反映土壤中汞含量富集过多后对草原的影响。

Background, aim, and scope Parts of large-scale coal enterprises in Inner Mongolia have been striving to develop coal-fired power plants and promoting the integration of coal and electricity, which indicates the rapid increase of coal consumption in the region of Inner Mongolia. During the coal combustion, the phenomenon of mercury emissions into the atmosphere appears, which has a serious impact on environmental pollution. This paper aims to explore the mechanism of how mercury in soil influences the growth of forage, and the effect to grassland caused by high mercury content in soil. Materials and methods In this study, test materials for alfalfa, cover with alkali grass, festuca arundinacea, grass seed were seeds from East Wuzhu Muqinqi grassland station in Inner Mongolia of Chinese Academy of Sciences. Test the soil collected from East Wuzhu Muqinqi grassland station in Inner Mongolia of Chinese Academy of Sciences. Peroxidase （POD） activity of guaiacol method is used to determine. Catalase （CAT） activity using ultraviolet absorption spectrometry. Malondialdehyde （MDA） using glucosinolates barbituric acid colorimetric method. Proline using sulfosalicylic acid method. Soluble protein using coomassie brilliant blue staining method. Soluble sugar content determination by anthrone method. Results Alkali grass and festuca arundinacea seed germination rate gradually reduced with Hg2＋ concentration in the soil, briefly in the early years of alfalfa seed germination, but high concentration of inhibition. In this paper, research has shown that, under the stress of Hg2＋ in soil, Hg2＋ concentration is lower than 1.5 mg·kg-1, alfalfa POD activity is on the rise, when the Hg2＋ concentration is greater than 1.5 mg·kg-1, alfalfa POD activity falling. Cover with alkali grass POD activity as a whole is on the rise. Tall fescue POD activity smoothly. Under the stress of Hg2＋ in soil, Hg2＋ concentration is lower than 2.0 mg·kg-1, the three kinds of forage grass CAT are on the rise, and when the concentration of Hg2＋ is higher than 2.0 mg·kg-1, all show the tendency of lower. The duration of alfalfa malondialdehyde content reduced; cover with alkali grass malondialdehyde content also is on the decline, to Hg2＋ concentration is higher than 32.0mg·kg-1 after the previous deal with higher concentration of content; festuca arundinacea MAD content tends to reduce the rising trend, after first when soil Hg2＋ concentration is higher than 1.5 mg·kg-1, malondialdehyde content increased. Three kinds of grass under the low concentration, soluble protein content were higher than that of no stress state, with increasing stress concentration, reduce gradually, appeared rise to high levels of stress condition. Three kinds of forage grass appears content change trend of the change of different concentrations of DNA showed that three kinds of forage grass active Hg2＋ stress influence degree is different. Analysis of soluble sugar content, soluble sugar content of alfalfa under Hg2＋ stress reduction, tall fescue in mercury concentration higher than 32 mg·kg-1 with elevated levels, cover with alkali grass in Hg2＋ stress state soluble sugar content is higher than no stress state. Instructions in the accumulation of soluble sugars, alkali grass has more obvious advantages. Discussion The normal development of mercury inhibition of plant roots and make plant becomes short. POD in organism can eliminate oxygen free radical, superoxide, inhibit free radicals on membrane lipid peroxidation, preventing damage to membrane damage and, at the same time outside the POD also participated in the film the generation. CAT can be reduced by H2O2 in plants, and reduced H2O2 accumulation in the body and limiting oxygen damage potential. CAT, POD is enzymatic defense system of plants to membrane lipid peroxidation of protective enzyme. Mercury by acting on the cell membrane phospholipids, make the cell membrane permeability change. Plants under the stress of mercury, active free radicals content in cells, membrane peroxidation of unsaturated fatty acids, which makes the structure and function of membrane is destroyed. MDA content can reflect the degree of membranous peroxide, reflect the extent to which plants suffer adversity harm. Plants can represent proline content in plant resistance, high proline content, strong resistance. Soluble protein content in plant cells can directly reflect the state of intracellular protein synthesis, denaturation and degradation. Proline and reduce the effect of the water in the cell, which can be more efficient for a variety of enzymes and complex protein quaternary structure protection, system stability in the adversity of cell and reduce the membrane lipid peroxidation. Soluble sugar of plant adversity. The more soluble sugar, the stronger the resistance of plants, there was a positive relationship. Conclusions Under Hg2＋ stress, inhibition of grass seed germination rate, and the higher the concentration of, the lower the germination rate, affect the plant height. Peroxidase activity and CAT activity and MDA content, proline content and soluble protein content, soluble sugar content changes under the stress of mercury, and the higher the concentration, the greater the long-term accumulated after mercury will have an impact on the prairie grasses. Recommendations and perspectives Current grassland mercury accumulation quantity is less, but should attach importance to the control of mercury from coal-fired power plants, to prevent the accumulation of prairie grass pollution, prevent the mercury in coal from entering the food chain, ecological health.