Author/Authors :
EKBERLİ, İmanverdi Ondokuz Mayıs Üniversitesi - Ziraat Fakültesi - Toprak Bilimi ve Bitki Besleme Bölümü, Turkey , KARS, Nalan Ondokuz Mayıs Üniversitesi - Ziraat Fakültesi - Toprak Bilimi ve Bitki Besleme Bölümü, Turkey
Abstract :
Effects of increasing dose applications (0.5 ppb, 1 ppb and 2 ppb) of 2,4 dichlorophenoxyacetic acid (2,4-D) herbicide on changes in catalase enzyme activity and kinetic parameters (Vmax, Km and Vmax/Km) in clay and sand textured soil were investigated depending on substrate concentrations. Moisture contents of the soils were completed to 40% of maximum moisture holding capacity by weighing them daily. Kinetic parameters of enzyme activity were calculated using the enzyme activities in different substrate concentrations of the soil samples taken 15., 30., 45., 60., 75. and 90. days of the experiment. In increasing applications of 2,4-D herbicide, significant differences (P 0,01) were determined among the incubation periods while effect of increasing doses on catalase enzyme activity was not significant. The highest catalase activity in both clay and sand textured soils was determined in 15 days of incubation. Catalase activities in clay and sandy soil decreased after 30 and 45 days of incubation, respectively. After these days, changes in catalase activities were found to be non significant statistically. While the mean values of Vmax, Km, Vmax/Km parameters in control, 0.5 ppb, 1 ppb and 2 ppb 2,4-D applications for clay soil were 0.785; 1.016; 0.923; 0.888 ml O2 g^-1 sec^-1; 2.608; 3.464; 2.953; 2.697 ml O2 g^-1; 0.428; 0.410; 0.418; 0.463 sec^-1, respectively, these values for sandy soil were determined to be 0.201; 0.211; 0.298; 0.232 ml O2 g-1 sec^-1 ; 0.422; 0.355; 0.629; 0.255 ml O2 g^-1; 0.839; 1.832; 1.103; 1.462 sec^-1, respectively.
NaturalLanguageKeyword :
enzyme , substrate , pesticide , incubation , kinetic parameters , Michaelis , Menten Equation
