| Eggplant is one of major farm crops in Guangxi,sown area around 20,000 hm2 in average year.As been planted in intensity and large scale,infestation of root-knot nematode has become one of increasing diseases in eggplant in recent years.In this research,fluopyram was applied by chemigation to control eggplant root-knot nematode to probe the eligible parameters.Besides,research was conducted on development of eggplant root,functional diversity of soil microbial community and activity of soil enzyme to verify this method safety to both eggplant and soil ecological system under the eligible parameters.The aim of the research is to supply basic data and theoretical basis for controlling eggplant root-knot nematode by fluopyram applied by chemigation.The orthogonal experiment was designed based on three factors:rate of fluopyram,drip irrigation water volume and flow velocity.According to the field control efficacy of eggplant root-knot nematode and the effect of fluopyram on development of eggplant root and functional diversity of soil microbial community,rate of 60 g·hm-2,volume of 200 L·hm-2 and flow velocity of 2 L·h-1 were selected to be the eligible parameters of chemigation.Two-time field experiments were conducted to verify the stability of 41.7%fluoropyrimidine SC in chemigation on controlling eggplant root-knot nematode under the eligible parameters.The general control efficacy on eggplant root-knot nematode on day 7,15 and 30 after treatment were 56.55%,62.60%and 69.51%,respectively in May 2018.While the general control efficacy on eggplant root-knot nematode on day 7,15 and 30 after treatment were 56.93%,62.31%and 70.22%,respectively in August 2018.The control efficacy of root-knot nematode in different soil sampling spots showed a normal distribution trend that the best control efficacy in the center area under drip dropper and control efficacy decreased gradually with distance in the surrounding area.There was no significant difference in control efficacy between the two-time field experiments result.The effect of fluopyram on the growth of eggplant roots was determined.The results indicated that root length of the treatment was significantly lower than that of the control on day 7 after treatment,and then it grew normally.On day 30 after treatment,there was no significant difference in root length between the treatment and the control.The changes of root surface area and volume were similar in the treatment:on day 7 after traetment,the inhibition was obvious,but on day 30 after treatment,there was no significant difference between the treatment and the control.The average root diameter of the treatment was insignificantly affected.There was no significant difference between the two field experiments result.Fluopyram had no effect on the development of eggplant root.The effect of fluopyram on functional diversity of soil microbial community was determined.The results showed that the AWCD value and Shannon index of the treatment were significantly lower than those of the control on day 30 after treatment.Simpson index of the treatment experienced a trend of increasing firstly and then decreasing.There was no significant difference between the treatment and the control on day 30 after treatment.McIntosh index of the treatment was significantly higher than that of the control on day 30 after treatment.There was no significant difference between two-time field experiment results.Floupyram changed functional diversity of soil microbial communities.The effect of fluopyram on activity of soil enzymes was determined.The results indicated that the inhibition rate of urease activity decreased gradually from day 3 to day 21 after treatment,and there was no significant difference between the treatment and the control on day 30 after treatment.The inhibition rate of soil urease activity was most obvious in the center area below drip dropper,and decreased gradually with distance in the surrounding area.appeared to be normal distribution.The effect of fluopyram on soil ?-glucosidase activity was similar to that of urease activity that from day 7 to day 14 after treatment,the inhibited rate of soil ?-glucosidase activity decreased.On day 21 after treatment,there was no significant difference between the soil ?-glucosidase activity of the treatment and that of the control.The inhibited rate of soil ?-glucosidase activity at each sampling spot was also most obvious in the center area below drip dropper,and decreased gradually with distance in the surrounding area,appeared to be normal distribution.The activity of alkaline phosphatase in soil of the treat was higher than that of the control in the prior and middle period after treatment.The activity of soil alkaline phosphatase reached its peak on day 7th after treatment.The activity of soil alkaline phosphatase of the treat was slightly lower than that of the control from day 21 to day 30 after treatment,but there was no significant difference between the treat and the control at last.Residue of fluopyram in eggplant fruit was 0.076 mg·kg-1,below maximum residue limit of fluopyram in eggplant fruit.Overall,control efficacy on eggplant root-knot nematode of fluopyram applied by chemigation was efficacious and stable.Application prospect of this method is wide. |
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