ALLEVIATION OF INJURIOUS EFFECTS OF SULFUR-DIOXIDE ON SOYBEAN BY MODIFYING NPK NUTRIENTS

Soybean (Glycine max L. JS-72-44) plants were grown at three mineral n utrient levels: NPK recommended dose, double NPK recommended dose and without nutrient application. The effects of sulphur dioxide and ferti liser singly as well as in combination on soybean plants were studied by exposing 30-day-old plants to 0.15 p.p.m. SO, for 4 h day(-1), 5 da ys week(-1) for 6 weeks. Photosynthetic pigments, ascorbic acid and pr otein contents, biomass and productivity were quantified prior to fumi gation and at 15 day intervals until the plants were 75 days of age. F ollowing SO2 exposure, all parameters decreased, the maximum reduction being in plants grown without nutrient application. The study suggest s that plants receiving recommended amounts of fertiliser are not as s everely injured by SO2 as an unfertilised crop, but an increase in fer tilisation above the recommended level did not provide further protect ion.