有机磷农药对大蒜素含量的影响及其原因

在不同浓度乐斯本、对硫磷灌根胁迫条件下,测定大蒜生长过程中大蒜素含量及农药的残留量.结果表明,低浓度胁迫条件下,大蒜素含量的变化趋势为先上升后下降再上升;高浓度时,表现为先下降后上升;大蒜素含量与两种农药使用浓度有明显的负剂量效应关系,相关系数均大于0.85,乐斯本、对硫磷残留量分别在用药后5 d、7 d未检出.通过化学分析得知,有机磷农药与大蒜素或蒜氨酸(大蒜素的前身)间可能发生两种作用:1)有机磷农药水解成碱性,与蒜氨酸或蒜酶发生酸碱中和反应;2)蒜氨酸与有机磷农药分子中都有双键,两者间发生了双键聚合反应.研究结果为大蒜的安全生产及加速有机磷农药降解剂的研究与开发提供了理论依据.

Effect of selected organophosphorus pesticides on allicin content in garlic and its reasons

The authors are inclined to present their study on the effect of different concentrations of chloryrifos and parathion on the allicin content in Garlic. As is known, the content of allicin can be determined with the method of fix sulfur, and the residues of selected organophosphorus pesticides (OPPs) are determined by GC. The results of our study show that the content of allicin tends to increase first and then decrease and afterwards increase again at low concentrations of pesticide, but in the condition of high concentrations, it tends to increase at first and then decrease. It is also found that there exists a significant dose-dependant relationship between pesticides and allicin content, as the dose increases, the allicin amount gradually decreases too. The relative coefficient proves to be over 0.85. Thus, it is also possible to determine the residues of chloryrifos and parathion respectively in 5 and 7 days in the process of the garlic growing. In addition, we proved the reason for the possible change by means of chemical analyses. Actually there are two kinds of reaction likely to take place between the selected OPPs and allicin or alicin, which are as follows: (1) The selected OPPs take basic hydrolysis and then acid-base neutralization with the alliinase; (2) Since both the acid-base molecules and the organophosphorus pesticide molecules are double-bonded, they are apt to react to the polymerization ion with P=S double-bond of the selected OPPs. Thus, the above study proves to be helpful in providing a theoretical basis for producing garlic safely and developing a new material that is able to accelerate the degradation of OPPs.