| Experiments in pot trial and fields were conducted to evaluate the efficacy of aluminium phosphide as a potential methyl bromide (MeBr) alternative in tomato and cucumber infested with root-knot nematodes. The growth of tomato and cucumber as well as the yield of tomato were also studied. The effect of aluminium phosphide on soil microbes activities by the population of the soil microbes, soil respiration, soil hydrolase, soil oxidoreductase were studied as well to fully evaluate the efficiency of aluminium phosphide.1. In the pot trials,the results showed that aluminium phosphide could effectively control tomato root-knot disease. When doses of aluminium phosphide (18.75 kg·ha-1, 37.50 kg·ha-1, 56.25 kg·ha-1) were applied in the nematode infested soil, the root-knot index was significantly reduced. There is a significant correlation between application rate and control effect. The control effect advanced along with the concentrations of the aluminium phosphide. The average control effectiveness of three concentrations were 50.00%,56.67% and 63.33% 60 days after transplanting (DAT). The control effectiveness of contrast nematicide(7.5 L·ha-1) avermectin was 60.00%. The control effect of high rate of aluminium phosphide is better than avermyctin.2. In four field trials, our results consistently indicated that 56% aluminium phosphide at the dose of 18.75 kg·ha-1, 37.50 kg·ha-1 and 56.25 kg·ha-1can significantly control the tomato and cucumber root-knot nematodes. MeBr was generally superior to the treatments including aluminium phosphide and avermyctin, which in turn were superior to the control, for inhibiting nematode. In all field experiments, aluminium phosphide at the dose of 56.25 kg·ha-1 has the most obvious efficiency in reducing the number of nematodes in 100 g soil and root galling, which is equivalent to MeBr.3. In pot trial and field trials, the effect of 56% aluminium phosphide on tomato and cucumber height was studied. In pot trial, there were no significances in plant height among treatments involving aluminium phosphide, avermyctin as well as MeBr on 15DAT, while on 25DAT, plant height in the plots treated with aluminium phosphide was greater than the untreated control plots and avermyctin treated plots. On 35DAT, aluminium phosphide at the dose of 56.25 kg·ha-1 has the greatest height. In the field trial, aluminium phosphide at the dose of 18.75 kg·ha-1,37.50 kg·ha-1 and 56.25 kg·ha-1 all enhanced the plant height significantly on 30 and 50DAT, which is greater than the avermyctin treatment and untreated control. And the aluminium phosphide treatment at the dose of 56.25 kg·ha-1 has the similar effect on plant height with MeBr.4. In pot trial and field trials, the effect of 56% aluminium phosphide on tomato and cucumber stem meter was studied. There was no significant difference in the stem meter among the plots treated with aluminium phosphide and the untreated control plots, but treatments involving aluminium phosphide have greater stem meter than avermyctin.5. The results from the field trial indicated that aluminium phosophide could give greater tomato and cucumber yield. All three treatments with aluminium phosophide had much greater yield than avermyctin and untreated plots, and the highest rate of aluminium phosophide produced the most tomatoes and cucumbers.6. In the field trial, the effect of two different kinds of plastic film on the efficiency of aluminium phosophide was studied. The 0.1 mm black polyethylene plastic film could give better results in reducing the number of nematodes in 100 g soil and root knot nematodes in the treatment of aluminium phosphide at the dose of 18.75 kg·ha-1. The control effectiveness of aluminium phosphide at the dose of 18.75 kg·ha-1, 37.50 kg·ha-1 and 56.25 kg·ha-1 were 66.67%, 56.67% and 31.67%. While the effectiveness were 64.91%, 50.88%, 24.56% in the plots which were covered with 0.038 mm white polyethylene plastic film. Plastic film with better impermeability could give better result in nematode control.7. The study of the aluminium phosphide on the population of the soil microbes was done by the plate-dilution method. All concentrations (0.1, 1, 10 mg·g-1) can effectively inhibited soil bacteria. During experiment period, the lowest rate of aluminium phsphide showed inhibiting at first then this effect disappeared and the population of bacteria almost resumed to normal. The effects on fungi showed inhibition, and the inhibiting effect was not resumed during experiment period. The greater the rate of aluminium phsphide, the greater the inhibition was. Concentrations of aluminium phsphide on the aceinomyces showed similar effects with fungi. In the field experiment, aluminium phsphide in common doses did not show significant effect on the population of bacteria, fungi as well as aceinomyces in the treatmens. 8. Effects of aluminium phosphide(0, 0.1, 1, 10 mg·g-1)on soil respiration were studied by using the close and direct absorption method. The result showed that 2 days after treatment with aluminium phosphide the respiration of the soil was restrained. The restrained effect of aluminium phosphide (10 mg·g-1) was the most, the inhibition rate was 77.28%. 20-30days after treatment, the respiration of the soil was stimulated by the treatment with the dose of 0.1 mg·g-1 and 1 mg·g-1. Aluminium phosphide at the dose of 10 mg·g-1 showed inhibition at first (0-11d), then the inhibition was changed to stimulating effect (11-30 d).9. The effect of aluminum phosphide on the activities of urease, invertase and hydrogen peroxidase in the soil at the dose of 0.1, 1 and 10 mg·g-1 was studied. The results indicated that, upon application as soil fumigation aluminum phosphide had inhibitory effect on soil urease during the experiment. The effects of low concentration of aluminum phosphide on the activities of soil invertase were stimulatory at first and inhibitory later, while high concentration of aluminum phosphide had strong inhibitory effect. The effects of low concentration of aluminum phosphide on soil hydrogen peroxidase activities were inhibition-stimulation while high concentration stimulation-inhibition. There was no significant difference of the activities of soil hydrogen peroxidase after 30 days of treatment. In the field experiment, aluminum phosphide with the dose of 18.75 kg·ha-1, 37.50 kg·ha-1 and 56.25 kg·ha-1 showed less strong effect on soil enzyme, and returned to the untreated control after a period. |
PDF Full Text Request