THE ACCUMULATION OF ARSENIC IN RADISH BIO MASS WHEN DIFFERENT FORMS OF AS WERE APPLIED IN THE SOIL

The effect of three forms of arsenic (As) compounds on the growth of r adish and the As accumulation in roots and leaves was investigated in the model pot experiment with three soils differ in physical-chemical properties and in the total As soil content. Five kg of soil (fluvisol , chernozem, and luvisol) was mixed with N, P, K fertilizers and water solution of As. Sodium arsenate, sodium arsenite and dimethylarsinic acid were tested at two elevated rates (10 and 100 mg of As per pot). Radish was planted twice at each pot. First growing period was immedia tely after application of solution and the second one a year later. Th e amount of available soil As was determined by extraction of 0.01 mol .l(-1) CaCl2 solution after each harvest. The results have shown signi ficant differences in the growth of radish and As accumulation in plan t tissues according to applied As form. The As behaviour was affected by the rate and soil used in the experiment. Higher yield reduction wa s found in the first growing period than in the second one. Higher As rate caused significant yield reduction in all treatments. The most to xic effect was found after application of dimethylarsinic acid. In flu visols and chernozems plants died in the first growing period, in the second period plants died only in fluvisols. Inorganic As forms showed significantly lower yield reduction, arsenate was more toxic than ars enite. Distribution of arsenic among plants was affected by the rate o f As. Plants growing at lower As rate accumulated more As in leaves th an in roots. The relationship of As accumulation changed in plants tre ated by higher rate of As, probably due to protection of assimilate or gans. Higher As content was found in roots than in leaves. The As accu mulation follows the As-org >> As-v > As-III order in both roots and l eaves in the first growing period. The application of As has not chang ed dramatically the amount of available As content. As forms had not a ffected the As content in the solution of calcium chloride, what confi rms a hypothesis of specific As uptake from different As forms.