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In concurrent with global warming, precipitation regimes are predicted to change as well around the world. In this study, two experimental sites were selected with different nutrient availability along a slope to study the effects of simulated increased precipitation on soil β-glucosidase activities in an Inner Mongolian grassland. Soil samples were adjusted to 55% of water holding capacity and incubated at 22°C in the dark for 32 days. Soil β-glucosidase activities were measured prior to and after the incubation. Results showed that soil β-glucosidase activities had differential responses to increased precipitation with a significant increase in the downslope site, but not in the upslope site. Correlation analysis showed that the initial soil β-glucosidase activities exerted a significantly negative relationship with soluble organic nitrogen (N). Our results indicated that both water availability and soil soluble N availability played important roles in regulating β-glucosidase activities in this semiarid region.
A pot experiment was carried out to determine the effect of soil (loamy sand and sandy loam) contamination with copper doses of 0, 150, 450 mg Cu·kg-1 d.m. soil on the activity of β-glucosidase (EC 3.2.1.21), acid phosphatase (EC 3.1.3.2), alkaline phosphatase (EC 3.1.3.1) and arylsulfatase (EC 3.1.6.1) in soil. The resistance of these enzymes to copper pollution was also estimated. Soil samples were contaminated with copper chloride. The experiment was carried out in five replications, in two series. The first series was performed on uncropped soil and the second one — on cropped soil. The experimental plants were oat, spring rape and yellow lupine. The activity of soil enzymes was determined in the analyzed samples on the 25th and the 50th day of the experiment. The results of the experiment showed that copper contamination in doses of 150 mg to 450 mg·kg-1 soil significantly inhibits soil’s biochemical activity. The sensitivity of the tested enzymes to copper was determined in the following order: alkaline phosphatase > arylsulfatase > acid phosphatase > β-glucosidase. The resistance of the above enzymes to copper depended on the cultivated plant spe- cies, soil type and the type of soil use and management. In samples of sandy loam, copper induced the smallest change in the activity of acid phosphatase and alkaline phosphatase, and in loamy sand — in the activity of arylsulfatase and acid phosphatase. In uncropped soil, copper was the least effective in changing the activity of arylsulfatase and acid phosphatase. All of the tested enzymes were less resistant to copper contamination in cropped than in uncropped soil. In soil planted with oat, β-glucosidase was the most resistant and arylsulfatase was the least resistant enzyme to copper contamination. In samples sown with spring rape, the analogous enzymes were arylsulfatase and alkaline phosphatase. In yellow lupine treatments, alkaline phosphatase was the most and β-glucosidase was the least resistant enzyme.
Four populations of J. communis L. subsp. communis of natural localities in forested regions of the Bory Tucholskie (Poland) were analysed in respect of phenolic compounds concentration and –glucosidase activity. The variability noted in needles was confirmed by adaptation changes; water-logged and poor insolated localities (deciduous mixed fresh forest, dmff – no 3 and coniferous mixed bog forest, cmbf – no 4) stimulated the phenolics accumulation and enzyme activity. On the contrary, the level of phenolics in unripe berry-like cones was almost two fold lower under disadvantageous juniper growth and fructification conditions, whereas the mature berries from poor vigour plants were characterized by higher concentrations of these metabolites. Obtained results show that morphological variation of juniper population was accompanied by variability in phenolic metabolism.
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