Effect of arsenate and Arsenite on early seedling growth of rice

Abstract

Presence of arsenic in ground water is a grave concern now as it is used for drinking and crop irrigation. Arsenic load of soil in the areas of arsenic contaminated ground water is gradually increasing as more than 95% of such contaminated ground water is used for crop irrigation. An experiment was conducted to study effect of arsenate and arsenite on germination and early seedling growth of the popular rice variety shatabdi. Rice seeds were exposed to water contaminated with different concentrations (Control, 2, 4, 6, 8 and 10 ppm) of arsenate and arsenite during germination and seedling growth. Observations were taken on germination at every 24 hour interval up to seven days. Seedling length (cm) and dry weight (g) recorded after seven days and plant height stress index (PHSI) and tolerance index (TI) was calculated. The speed of germination under arsenate at 2 ppm and 4 ppm was at par with the control treatment and under further higher concentration of arsenate and in all concentrations of arsenite it was lower than the control treatment. Length of seedlings, dry weight of seedlings was found to decrease with increase in concentration of arsenic. Such decrease was higher in arsenite than arsenate. The results indicate that arsenate beyond 4 ppm and arsenite beyond 2 ppm only affected germination. But seedling growth was very sensitive to arsenic and was affected at all concentrations of arsenate and arsenite. Arsenite appeared to be more toxic than arsenate.