Some Effects of Air Pollutants on the Growth and Productivity of Plants

1. Fumigations with ozonated hexene caused a repression in growth of bean plants (varieties Red Kidney and Bountiful) even though they showed no visible symptoms of injury. This effect was evident from measurements of linear growth, leaf area, fresh and dry weights, and fruit production. 2. Both primary and trifoliolate leaves failed to enlarge as much as control leaves when treated with ozonated hexene, although the treatment seemed to have little or no effect on the number of leaves initiated. Primary leaves on treated plants aged and were lost prematurely. 3. Stems of plants treated with ozonated hexene consistently had a higher water content than did stems of control plants. The leaves did not show this relationship. 4. The height growth of pea plants (variety Alaska) was slowed temporarily by as little as a single half-hour fumigation with ozonated hexene, although treated plants fully recovered and were growing normally 1 or 2 days later. 5. Ozone alone caused no repression of growth, and repeated fumigations of pea plants with 1-hexene elicited no response.