The HPLC method for acetamiprid in soil and cowpea was developed. The degradation dynamics of the acetamiprid in the soil and cowpea and the last residue in the cowpea were researched. The method recovery was 81% - 88% and the linear relationship was good from 0.05 to 5μg·mL-1with a CV less than 5%, which could meet the detection requirement. The half-life of the acetamiprid were 3.3 days and 4.1 days, respectively in soil and cowpea. The residue of the acetamiprid in the cowpea was less than 0.5μg·g-14 days later when two times of the recommended dose. The half-life of the acetamiprid was short, which belongs to the easy degradation pesticide. The cowpea was sprayed 3 times, respectively with two times and 2.5 times of the recommended dose, which had a two days interval each time. The results showed that 4 days and 6 days later the acetamiprid residue in the cowpea were less than 0.5μg·g-1.
Banana fusarium wilt is one of the soil-borne diseases of seriously threat to banana production in the world. However, there is no effective method for prevention. The objective was providing theoretical basis for field diagnosis of banana fusarium wilt. Thirty rhizosphere and non-rhizosphere soil samples were collected from three typical banana plots (Jianfeng, Shiyuetian, Chongpo) infected by banana fusarium wilt. Applying dilution plate method to estimate the pathogenic number, fourteen soil physicochemical properties and nutrient concentrations were chemically determined. Results showed that pathogenic number and nutrient concentrations in rhizosphere soil were higher than non-rhizosphere soil, the pathogenic number and pH in rhizosphere soils significantly increased with increasing of plant infection grades, while the concentrations of available P and B decreased with increasing of plant infection grades. It was concluded that infection degree of banana plants was mainly determined by pathogenic number, pH and the concentrations of available P and B.
The pot experiment was carried out to study the effects of eight functional strains on growth promotion of tomato and resistance to tomato bacterial wilt. The results indicated that the two strains both Paenibacillus polymyxa and Bacillus megaterium could significantly increase the plant height of tomato; the two strains of Paenibacillus azotoformans and Bacillus laterosporus could significantly improve the stem diameter of tomato; the three strains of Paenibacillus polymyxa, Bacillus laterosporus and Paenibacillus azotoformans could significantly increase the average leaf area and chlorophyll contents of Tomato; the four strains of Bacillus subtilis, Bacillus licheniformis, Paenibacillus polymyxa and Streptomyces microflavus could obviously inhibit occurrence of tomato bacterial wilt. All above results indicated that Paenibacillus polymyxa could not only significantly increase the height, the average leaf area and chlorophyll content of tomato plant, but also could obviously reduce the incidence of tomato bacterial wilt. So this strain can be used as one of core strains to construct multifunctional composite inoculants.
Using pot experiment to study the influence of three organic fertilizers of chicken manure compost (CM), activated sludge (AS) and cassava residue compost (CR) on the degradation of p, p'-DDT in clay soil under flooding conditions. The results showed that the two kinds of organic fertilizers of AS and CM could effectively accelerate the degradation of p, p'-DDT in clay soils, and the degradation effect was the best when adding 2% CM or 3% AS in clay soil. However, the influence of CR on the degradation of p, p'-DDT was not obvious. The degradation rates of P, P′-DDT in the treatment on adding 1% AS were from zero to 7.4% higher than that of 1% CM. The degradation rates of P, P′-DDT in the treatment on adding 2% AS were from zero to 11.3% higher than that of 2% CM. The degradation rates of P, P′-DDT in the treatment on adding 3% AS were from 8.3% to 27.4% higher than that of 3% CM. which indicated that AS is more conducive to the degradation of p, p'-DDT in the clay.
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