玉米根系对苯并(a)芘的吸收及苯并(a)芘在植株内的积累

在人工气候室内用Poagland营养液栽培玉米,测定了玉米根、叶、茎、粒及伤流液中BaP的本底值。表明玉米根系可以吸收BaP并向上运输,但地上部的累积在一定程度上取决于根系环境中BaP的量。 在玉米的不同生育期向培养液添加BaP的试验表明,灌浆期的添加会增加籽粒中BaP的累积,因此,避免土壤的严重污染对控制进入食物链的BaP量是有意义的。

ABSORPTION OF BaP BY CORN ROOTS AND ITS ACCUMULATION IN THE PLANTS

Until now, there has been a problem whether plants can absorb BaP from soil and accumulate it in shoots. In this study, an attempt was made to expound the problem.Corn (Zea mays L. imdentata) seedlings were cultured in Hoagland solution in the phytotron. The background contents of BaP in roots, leaves, stems, seeds and bleeding sap were 15.5, 6.T, 2.8, 0.22 and 0.04 ppb, respectively. When corn seedlings were grown in the culture solution with 20, 100, 500 ppb BaP, it was found that the concentration factor of corn roots for BaP was 102-104, and that below 100 ppb, the BaP contents in corn shoots were not different from that of control, but above 500 ppb, the BaP contents in corn shoots and bleeding sap increasedsignificantly. It indicated that corn roots can absorb BaP and transport it up to shoots, the accumulation of BaP in shoots, however, depended to a certain extent on the amount of BaP in the root environment.BaP was added to the culture solution at various growth stages of corn plants. The accumulation of BaP in seeds increased when it was administered at the seed-filling stage, though in little amount. And after harvest, the BaP residue in seeds, shoots, roots and the total amount added in was in the ratio of 1:10:30000:300000.It is contemplated that the BaP content in shoots was the final of the balance among the biosynthesis, uptake and degradation of BaP in plants. In order to control BaP entering the food-chain, therefore, it is important to avoid the serious soil pollution with BaP.