Abstract: When 1/15 mol/L of phosphate buffer at pH 6. 4, was used to spray wheat seedling three times, the plasmolemma structure become stabilized and k+ efflux was decreased. After fumigation with SO2 the K+ efflux of wheat seedling ,sprayed with phosphate buffer, decreased markedly. At SO2 dosage of 1.54 ppm × 4h, the decreasing rate of K+ efflux was 54. 11%–81.29% and the decrease rate was in concert with the increase of SO2 dosage. Therefore, the authors consider that the phosphate buffer, at pH 6.4, has a good protective effect against SO2 insult.

Key words: phosphate buffer, K+ efflux, Wheat seedling