大豆轮作与连作对黑钙土酶活性和动力学特性的影响

Effects of Different Cropping Systems of Soybean on Chernozem Enzyme Activities and Kinetic Parameters

大豆连作减产是制约大豆单产提高的重要因素,拟通过对大豆连作、大豆-玉米轮作和大豆-高粱轮作制度下土壤酶活性及酶动力学特性的研究,阐明大豆轮作与连作对土壤生物学质量的影响。测定了与土壤碳、氮、磷、硫转化有关的9种酶的酶活性(α-半乳糖苷酶、β-半乳糖苷酶、α-葡糖苷酶、β-葡糖苷酶、脲酶、蛋白酶、磷酸单酯酶、磷酸二酯酶、芳基硫酸酯酶),以及β-葡糖苷酶、脲酶、蛋白酶、磷酸单酯酶、磷酸二酯酶和芳基硫酸酯酶的动力学参数。结果发现:大豆-玉米轮作全硫量降低幅度最大;大豆-玉米轮作制度下土壤β-半乳糖苷酶、β-葡糖苷酶和蛋白酶的活性与大豆连作相比有显著提高。大豆-高粱轮作制度下除β-半乳糖苷酶活性显著低于大豆连作外,其它均与连作方式无显著差异。大豆-玉米轮作制度显著降低了β-葡糖苷酶和磷酸二酯酶的Km值,显著提高蛋白酶、磷酸单酯酶和芳基硫酸酯酶的Vmax值,以及磷酸单酯酶和磷酸二酯酶的Vmax/Km值。大豆-高粱轮作制度可以显著降低土壤脲酶的Km值,显著提高脲酶和芳基硫酸酯酶的Vmax/Km值。3种种植制度下,大豆-玉米轮作制度对酶活性的提高作用较大。

Continuous cropping decrease soybean yields. To understand the effects of different cropping systems of soybean on the activities and kinetic parameters of enzymes related to the C, N, P and S transformation in chemozem, surface soil （0- 20 cm） samples were collected from the experimental fields under soybean continuous cropping,soybean-maize rotation,and soybean- sorghum rotation in Daqing City of Heilongjiang Provinee, and the activities of α- and β- galactosidase, α- and β- glucosidase, urease, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase, as well as the kinetic parameters of β- glucosidase, urease, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase were measured. The results showed that under soybean-maize rotation, the activities of β- galactosidase, β- glueosidase and protease increased significantly, while arylsulphatase activity had the greatest decrease, eompared with those under soybean continuous cropping. Under soybean- sorghum rotation, the activities of all test enzymes except β- galactosidase had no significant differences with those under soybean continuous cropping. Soybean-maize rotation decreased the Km value of β-glucosidase and phosphodiesterase but increased the Vmax value of protease, phosphomonoesterase and arylsulphatase as well as the Vmax/Km ratio of phosphomonoesterase and phosphodiesterase significantly, while soybean- sorghum rotation decreased the Km value of urease but increased the Vmax/Km ratio of urease and arylsulphatase significantly. Compared with other two cropping systems soybean-maize rotation can increase soil enzyme activity better.