| Abstract: | The effects of exposure to SO2 (50 and 400 µg m–3SO2) on the growth, photosynthesis, and respiration of perennialryegrass (Lolium perenne L.) cv. S23 were examined in two successivegrowth periods of 29 and 22 d. At the higher concentration ofSO2, there was some visible injury of the leaves and specificleaf area was reduced, but yield, net photosynthesis, and darkrespiration of the plants were not significantly affected byexposure. The treatment was also without effect on the transpirationcoefficient of the plants and their number of tillers. The plantsexposed to the lower concentration of SO2 showed no signs ofinjury and did not differ in any of the measured characteristicsfrom plants grown in SO2-free air. Content of S in the shootsincreased linearly with the concentration of SO2, the additionalS being found in the sulphate fraction whilst organic S wasunchanged. The results are discussed in relation to earlierfindings that yield of ryegrass exposed to SO2 may be reducedwithout visible signs of injury. |
