| Bitter gourd is one of the important economic crops in China.In recent years,a large-scale outbreak of soil-borne diseases such as bitter gourd wilt and so on has been caused by continuous cropping of bitter gourd.It has severely restricted the production of bitter gourd,and caused significant economic losses.In order to prevent outbreak and epidemic of bitter gourd wilt,in this study effects of different dosages of dazomet and calcium cyanamide on the prevention and control of bitter gourd wilt have been investigated.The poting experiment has been conducted to find the appropriate dose of fumigant to control bitter gourd wilt.Control method of wilt disease has been obtained by application of fumigant added the bio-organic fertilizer in the field.Effects of dazomet and calcium cyanamide added microbial inoculium as well as the bio-organic fertilizer on the soil enzyme activities have been tested,respectively.The experiment results are as follows:Control on bitter gourd wilt using different dosages of dazomet and calcium cyanamide was investigated in poting experiment.The results showed that control effect of fumigants on bitter gourd wilt followed by:180 g/m~2>120 g/m~2>60 g/m~2for calcium cyanamide;60 g/m~2>45 g/m~2>30 g/m~2 for dazomet.The stem diameter of the bitter gourd treated with fumigant was increased to some extent,and the treatment with dazomet was increased with the increasing of dose,but the increasing of calcium cyanide was decreased with the dose increasing.Therefore,45-60 g/m~2 was chosed for dazomet dosage,and 60-120 g/m~2 for calcium cyanide.Effects of fumigants and microbial inoculants on the activities of urease,sucrase and catalase were tested in root region soil of bitter gourd in potting test.The results showed that activity of urease was irreversibly inhibited in treatment with dazomet,but for the activities of sucrase and catalase,with the passage of time,the treatment with microbial inoculants could reduce the degree of inhibition against enzymes activities.The treatment with calcium cyanamide indicated a tendency to suppress-activate-inhibit the activity of urease.Degree of enzymes activation of the treatment with microbial inoculants was higher than that of treatment without microbial inoculants.The activities of sucrase and catalase were inhibited in the treatment with microbial inoculants.With the prolongation of time,treatment with microbial inoculants could reduce the degree of inhibition.The results showed that the disease index of treatment with dazomet+bio-organic fertilizer and calcium cyanide+bio-organic fertilizer was lower than that of treatment with single fumigant,respectively.This indicated that control effect of the combination of fumigants and bio-organic fertilizer was better than that of the using single fumigant.Effects of fumigants and bio-organic fertilizers on the stem diameter and chlorophyll content of bitter gourd plants in the field were investigated.The results showed that the stem growth in treatments with dazomet and dazomet added bio-oganic fertilizer was 1.72 times and 1.52 times of the control treatment.The chlorophyll a/b ratio of bitter gourd plants in treatment with dazomet was120.6%and 135.3%of control treatment,respectively..The stem growth in treatments with calcium cyanamide and calcium cyanamide added bio-oganic fertilizer was 1.69 times and 1.48 times of the control treatments,respectively.The chlorophyll a/b atioof plants treated with calcium cyanamide was 119.70%and 121.30%of control,respectively.This indicated that treatment with fumigants could promote growth of plant and enhance efficiency of photosynthesis.Effects of fumigants and bio-organic fertilizers integration on the soils enzymes of Momordica charantia L.were detected.The results showed that the treatment with dazomet added organic fertilizer with the addition of time was able to eliminate the inhibition against urease and occurred the phenomenon of inhibition and activation.Urease activity of soil treated with calcium cyanamide added bio-organic fertilizer was higher than that of the control treatment,and urease activity was increased.The activity of sucrase was first activated and then inhibited in treatment with fumigant added bio-organic fertilizer,at 45 days but was higher than that of treatment with bio-organic fertilizer alone.At 45 days the activity of catalase in treatment with dazomet added bio-organic fertilizer was lower than that of treatment with bio-organic fertilizer alone,but the activity of catalase in treatment of calcium cyanamide added bio-organic fertilizer was higher than that of bio-organic fertilizer only.All the treatment with fumigants added bio-organic fertilizer was higher than that of treatment with only bio-organic fertilizer.Therefore,the cooperation between dazomet or calcium cyanamide and bio-organic fertilizer could improve the activities of soil enzymes to a certain extent.This was beneficial for the ecological restoration of soil microbial environment. |
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