Bt杀虫晶体蛋白的土壤残留及其对土壤磷酸酶活性的影响

研究表明以不同形式导入土壤中的杀虫晶体蛋白在土壤中的残留特性及其对土壤磷酸酶活性的影响有所不同。以Bt菌体向土壤导入杀虫晶体蛋白的试验表明 :随着培养时间的延长 ,土壤中杀虫晶体蛋白含量逐渐增加 ,到 1 5d时达到一个峰值 ,而后下降 ,在培养 30d时 ,杀虫晶体蛋白含量基本与初始含量相同。以不同Bt棉组织添加土壤的试验表明 :随着培养时间的延长 ,土壤中的杀虫晶体蛋白含量降低 ,在培养初期下降的速度较快 ,随后下降的速度较慢 ,在培养的中后期基本稳定 ,在培养 5 6d时 ,杀虫晶体蛋白含量为初始值的 4 4 7%(ZK)和 5 6 1 %(GK)。不同Bt棉的盆栽试验表明 :在整个生育期内 ,Bt棉花种植后根际土壤中杀虫晶体蛋白含量均明显比非Bt棉高。Bt菌体和Bt棉组织处理的土壤磷酸酶活性均呈现出比对照高的趋势 ,而在Bt棉种植过程中Bt棉根际土壤的磷酸酶活性则呈现出比非Bt棉低的趋势。无论以何种方式向土壤中导入杀虫晶体蛋白 ,土壤磷酸酶活性在不同杀虫晶体蛋白浓度处理间的差异显著。

PERSISTENCE OF Bt TOXIN IN SOIL AND ITS EFFECTS ON SOIL PHOSPHATASE ACTIVITY

Experiments in lab indicated that the persistence of Bt insecticidal crystal protein (BICP) in soil and its effects on soil phosphatase activity were different between forms of BICP introduced into the soil. In the first treatment of the experiments, Bt was applied directly into the soil with results showing that BICP concentration in the soil increased gradually along with the incubation time and reached the peak value on D15 and then decreased. On D30 the concentration of BICP was almost the same as at the initial stage after the application. In the second treatment, Bt cotton tissues were used. The results showed that BICP concentration in soil decreased along with the incubation time. There was a rapid decline at the initial stage of the incubations and the trend leveled off in the middle and late stages. On D56 of the incubation, BICP in soil was at 44.7% (ZK) and 56.1% (GK) of the initial values. In the third treatment, Bt cotton was planted in pots. Analysis of the soil showed that during the whole growth period, the concentration of BICP in the rhizospherice soil of Bt cotton was significantly higher than that of non-Bt-cotton. The treatment with Bt and Bt cotton tissues showed a trend of the soil phosphatase activity being higher than that in CK. But the phosphatase activity in the rizhospherice soil of Bt cotton was lower than that of non-Bt cotton. Whatever forms of BICP were introduced into soil, the difference in soil phosphatase activity between treatments different in BICP concentration treatment was significant.