Sensitivity of selected crops to lead, cadmium and arsenic in early stages of ontogenesis/Citlivost' vybranych pol'nohospodarskych plodin na olovo, kadmium a arzen v skorych stadiach individualneho vyvinu

This paper examines the influence of [Pb.sup.+2], [Cd.sup.+2] and [As.sup.+3] on growth of roots in legumes (broad bean, soybean, pea) and cereals (barley, maize). Roots of germinating plants were exposed to two different levels of [Pb.sup.+2] (300 and 500 mg*[L.sup.-1]), [Cd.sup.+2] (100 and 300 mg*[L.sup.-1]) and [As.sup.+3] (50 and 100 mg*[L.sup.-1]) during four day experiment. During this time, length of roots were daily measured. Toxicity of metal treatment on plant roots was calculated as phytotoxicity index (IP). In all cases, a moderate effect of lead treatment was observed (IP up to 56.67 %) while higher doses of cadmium and arsenic resulted in increase of IP above 50 %. In cases of barley and maize, the toxic effect of almost all test doses of the heavy metals was observed as soon as 24 hours after their application. Generally, a higher tolerance to tested metals showed roots of both bean cultivars (IP 16.27-69.53 %), while the most sensitive reactions had roots of barley and soybean (IP > 50 %, excluding dose Pb 300).