Abstract:

In order to explore the alleviating effect of exogenous ascorbic acid on the toxicity of beet seedlings under atrazine stress and the degradation mechanism of atrazine, using beet 'KWS1197' seeds as experimental materials, pot experiments combined with instrumental analysis were conducted to determine the effects of different concentrations of ascorbic acid on physiological and biochemical indexes of beet under atrazine stress, as well as the pesticide residues and degradation mechanisms in the soil. The results showed that atrazine stress inhibited the growth of beet seedlings, after spraying ascorbic acid, the toxicity of beet seedlings under atrazine stress was alleviated. Spraying 1mmol/L ascorbic acid had the most significant effect. The dry weight of the above-ground part and the underground part was 2.54 times and 3.43 times that of atrazine treatment group (AT treatment group). Chlorophyll content was increased by 42.5%. MDA content and electrolyte permeability were 53.57% and 65.01% of those in AT treatment group. SOD, POD and CAT enzyme activities were reduced by 60.5%, 61.3% and 51.1%, compared with AT treatment group. Spraying ascorbic acid can reduce the residual amount of atrazine in soil, and the higher the concentration, the more obvious the degradation effect. Four degradation products were found, and four possible degradation pathways of atrazine were further speculated. Ascorbic acid can improve the adverse effects of atrazine on the growth of beet seedlings, and the effect is significant at 1 mmol/L. This study provides a reliable reference for the degradation of atrazine.

Key words: atrazine, sugar beets, ascorbic acid, degradation, toxicity, physiological index