在陇东黄土高原苹果树5年生矮化密植园,采用 自动灌溉系统控制3个土壤含水量(高70％～80％、中50％～60％、低30％～40％),研究3种土壤含水量条件下,3类土壤菌(细菌、真菌、放线菌)在0～20 cm、20～40 cm 土层内的数量,4类土壤酶(过氧化氢酶、脲酶、蔗糖酶、碱性磷酸酶)的活性以及酶活性与菌类数量的相关性.结果表明,土壤细菌、真菌、放线菌的数量均随土壤含水量梯度的下降而减少,20～40 cm 土层中,含水量70％～80％处理的细菌、真菌、放线菌的数量均显著高于50％～60％、30％～40％含水量处理.土壤过氧化氢酶、脲酶、蔗糖酶、碱性磷酸酶的活性均随土壤含水量梯度的下降呈下降趋势;0～20 cm 土层的土壤酶活性高于20～40 cm 土层;含水量70％～80％处理的脲酶活性显著高于其他两个处理;土壤酶活性的高低与菌类数量有关,过氧化氢酶活性与细菌数量呈显著正相关,脲酶活性与放线菌数量呈极显著正相关,蔗糖酶活性与真菌数量呈极显著正相关,碱性磷酸酶活性与细菌、放线菌数量均呈显著正相关.综合来看,含水量70％～80％处理的土壤菌类数量多、酶活性高.
Effects of soil water content on soil microorganisms and enzyme activities in dwarf close-planted apple orchard
Three soil water contents(high 70％～80％,medium 50％～60％and low 30％～40％)were controlled by automatic irrigation system in a 5-year dwarf close-planted apple or-chard on the Loess Plateau of Longdong.The abundance of 3 types of soil microorganisms(bacteria,fungi,actinomyces)in 0～20 cm and 20～40 cm soil layers,the activities of 4 types of soil en-zymes(catalase,urease,sucrase,alkaline phosphatase),and the correlation between enzyme ac-tivities and the number of microorganisms.The results showed that the number of three types of soil microorganisms decreased with the decrease of soil water content gradients.In the 20～40 cm soil layer,the number of bacteria,fungi,and actinomycetes in the 70％～80％water content treatment was significantly higher than that in the 50％～60％and 30％～40％water content treatments.The activities of soil catalase,urease,sucrase,and alkaline phosphatase all showed a decreasing trend with the decrease of the three soil water content gradients.The soil enzyme activity in 0～20 cm soil layer was higher than that in 20～40 cm soil layer.The urease activity of 70％～80％water content treatment was significantly higher than the other two treatments.The level of soil enzyme activity was related to the number of fungi,and the catalase activity was significantly positively correlated with the number of bacteria.Urease activity was significantly positively correlated with the number of ac-tinomyces,sucrase activity was significantly positively correlated with the number of fungi,and alka-line phosphatase activity was significantly positively correlated with the number of bacteria and acti-nomyces.In summary,the soil microorganisms treated with 70％～80％water content were abun-dant and the enzyme activity was high.
dwarf close-planted apple orchardssoil water contentsoil fungisoil enzyme activity
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