Elementos-traço em Allium cepa L. e Lactuca sativa L.

Abstract

The environmental pollution with trace-elements (ETs) is an increasing problem in the modern society, having extreme importance the evaluation of these environmental risks. The use of seeds of superior plants is ideal for such tests since they are efficient, quick and of easy execution. The objectives of this work were evaluate the toxic effects on the germination and cytotoxics on the meristematics cells of Allium cepa L. and Lactuca sativa L. roots, under different concentrations of the trace-elements cadmium (0,5; 1,0; 3,0; 5,0; 7,0 and 9,0mg. L-1), arsenic (2,5; 5,0; 7,5; 10; 15; 20mg. L-1), lead (50, 100, 150, 200, 250 and 300mg. L-1), chromium (50, 100, 150, 200, 250 and 300mg. L-1) and mercury (0,25; 0,5; 1,0; 1,5; 2,0 and 2,5mg. L-1), after 168 and 48h of exhibition, respectively. In lettuce, de maximum number and classes of nucleolus per interphasic cell were observed. The results showed toxic effect of the traceelements on the germination of the seeds and Mitotic Index (IM), besides the induction of chromosomic aberrations in the meristematic cells of A. cepa L. The degree of toxicity and the different anomalies increased with the increase of ET concentration. In L. sativa it was evident that both the percentage of germination and the IM decreased with the increase of ETs concentration. The cytotoxicity caused by these ETs was demonstrated in the different chromosomic anomalies caused to the meristematic cells of this vegetable species. The presence of chrome, even in the lowest concentrations used in this study, impaired the events sequence of the germination process of lettuce seeds. Regarding the number of nucleolus, the studies demonstrated that, the lettuce has, at most, six (6) nucleolus per interphasic cell, even in the presence of the studied trace-elements.