SYSTEM FOR EXPOSING PLANTS TO ATMOSPHERES CONTAINING LOW CONCENTRATIONS OF SULFUR-DIOXIDE

A description is given of the construction and operation of a system of chambers in which plants can be grown in filtered air, with or without the addition of SO2. Concentrations of SO2 as low as 20 .mu.g m-3, which can be maintained in the chambers over prolonged periods, are monitored automatically by conductimetric and colorimetric methods of analysis. The plants are grown in pots containing soil and are watered by remote control, allowing exposure to SO2 for extended periods without interruption. The method of watering is based on loss of weight and gives an estimate of transpiration. A brief account is given of an experiment in which perennial ryegrass (Lolium perenne L.) cv. ''S23'' was grown in the chambers and exposed to filtered air containing 0, 50, 100, 200 and 400 .mu.g m-3 SO2. Exposure to low concentrations of SO2 alleviated S deficiency, but at the highest concentration there was evidence of a reduction in yield without visible signs of injury.