Effects On Fosthiazate To Soil Enzyme And Cucumber Seedling

Fosthiazate was a new nematicide. The effects of fosthiazate on the activities of soil enzyme activity, Safety of Cucumber Seedling and control of Meloidogyne incognita was studied in the pot trial and in greenhouse by soil application. It also studied the effects of fosthiazate on soil entironment and security of crop by soil hydrolase, soil oxidoreductase, three protective enzyme, root vigor, content of MDA of cucumber root.1. The effects of fosthiazate on the activities of soil urease, invertase, and catalase were studied in greenhouse by soil application. The results showed that fosthiazate had a significant effect on the activity of soil urease, with each concentration of fosthiazate showing a stimulation-inhibition-stimulation curve, the effect of each concentration on soil invertase showed a stimulation-inhibition action, but mostly with an inhibition effect. The low concentrations (10% pelletized granule 22.5 kg/hm2, 30 kg/hm2) showed a stimulation effect on soil catalase, the high concentration (60 kg/hm2) showed an inhibition effect, no significant difference existing between the stimulation and inhibition effect. The activities of soil urease and invertase returned to normal level gradually fifty days after application.2. The result of laboratory trial was similar to the pot trial. The activity of soil urease was stimulated then was inhibited, and then stimulated at each concentrations (0.5,1,5,10,50,100μg/g). Fosthiazate caused stimulation of soil invertase activity and then inhibition, and then resume to the level as the control. No significant difference existed between the stimulation and inhibition effects on soil catalase. The soil phosphatas activity was inhibited, and the inhibition rates increased with concentration.3. In the pot trial, the results showed that fosthiazate could econtrol tomato root-knot disease ffectively. When the nematode infested soil added with fosthiazate(22.5,30,45,60 kg/ hm2), the root-knot index was significantly reduced. There was a significant correlation between application dosage and control effect. The control effect advanced along with the concentrations of the fosthiazate. When tomatoes were transplanted 30 d, the control effectiveness of four concentrations were 92.84%, 93.17%, 96.05%and97.07%. When tomatoes were transplanted 60 d,the average control effectiveness of four concentrations were 92.55%, 93.52%, 94.23%and95.20%. The results revealed similar results to that of pot experiment. The number of juveniles in soil was reduced significantly. After 30 d, the average effect was also above 80%.4. The effects of fosthiazate on the growth and development of root, root vigor, the content of malondialdehyde (MDA), the activities of superoxide dismutase (SOD), peroxidese (POD) and catalase (CAT) were studied through pot experiment. The results showed that, length and fresh weight of root were lower than the control at high concentrations(45,60 kg/ hm2), but there was no significant difference between the low concentrations(15,22.5,30 kg/hm2) and the control. Root vigor were higher than the control at the low concentrations(15,22.5,30 kg/hm2), and lower at the high concentrations(45,60 kg/hm2). The activities of SOD and POD at the low concentrations(15,22.5,30 kg/hm2)were equivalent with the control, but that were observably higher at high concentrations(45,60 kg/hm2) than the control. Both the activity of CAT and the content of MDA were higher than the control at each concentrations.