Activities of nitrate reductase and glutamine synthetase in rice seedlings during cyanide metabolism

► Seedlings grown on NH4+ were faster than those on NO3− in the presence of KCN. ► Both rice seedlings degrade cyanide quickly with minor accumulation in biomass. ► Activities of NR and GS in rice seedlings showed different responses to KCN. ► NR activity is more susceptible to change from cyanide application than GS activity. ► Exogenous KCN can be a supplementary nitrogen source to plant nutrition.