Growth of Perennial Ryegrass (Lolium perenneL.) Exposed to a Low Concentration of Sulphur Dioxide

Abstract

The influence of a low concentration of SO2 on the growth and sulphur status of perennial ryegrass (Lolium perenne L.) cv. S23 was examined in a system of specially designed growth chambers. For plants grown without additions of sulphate to the soil, exposure to filtered air containing 50 pg m-3 SO2 alleviated sulphur deficiency that developed during a sequence of successive harvests, and gave increased yield. The plants had higher contents of organic and inorganic sulphur than those grown with neither sulphate nor SO2. Plants grown with added sulphate showed no signs of sulphur deficiency and although exposure to SO 2 increased their sulphur content it had no effect on yield. The coefficient of transpiration (g water transpired g_1 dry wt. of shoots) was reduced when plants which otherwise had an inadequate supply of sulphur were exposed to SO2; for plants with adequate supplies of sulphate, it was similar whether they were grown with or without the addition of SO2 to the air. The results are discussed in relation to other known reactions of plants to SO2.