Phytotoxicity of thiocyanate to rice seedlings.

The acute toxicity of potassium thiocyanate (KSCN) and ammonium thiocyanate (NH(4)SCN) to rice seedlings was tested. Hydroponically-grown plants showed different responses to the two species of thiocyanate. NH(4)SCN caused more severe stress to rice seedlings than KSCN. A significant reduction in transpiration and relative growth was observed with all NH(4)SCN treatments (p < 0.01), while the effect of KSCN on rice seedlings was more evident at greater than 100 mg SCN/L (p < 0.01). Both chemicals had a negligible effect on total chlorophyll content in shoots of rice seedlings (p > 0.05). Although phyto-transport of thiocyanate was apparent, rice seedlings showed significantly higher removal potential for NH(4)SCN than KSCN.