Abstract

                                Hydrogen sulphide is toxic to plants even in small puantities. It causes injury to the root cells and inhibits respiration. The toxicity is a function of the concentration and time of contact of H.S with the plant. The injury increases with time of exposure of the plant to the gas even in minute quantities (1. 2). The uptake of nutrients is vitally affected and Baba et al, (3) from their studies on the nutrition of rice showed that the absorption of some nutrients particularly potassium and silica and of water was decreased by the addition of H.S. As a result of similar studies, Mitsui et al, (4, 5) showed that passing HS through the culture solution at the rate of two bubbles a second for 30 minutes caused a market reduction in ion accumulation, water absorption and protein synthesis during the subsequent 23 hours. Ion uptake was roduced in the following order: P₂O5 KO Sio> NH2 MnO> HO> Mgo CaO. They concluded that the severe Helminthsporium root rot noticed in certain soils was a result of HS injury. The toxicity due to HS is believed to be the cause of the disease known locally in Japan as 'AKIOCHI or autumn disease which is prevalent in old sandy degraded soils (6). The subject has rightly received more than passing interest in Japan and detailed studies have been made there with reference to the conditions favouring HS toxicity and ameliora- tive mehods to be adopted to prevent the disease.

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