Physiological Activity of Wheat cv. Tonacja Seedlings as Affected by Chemical Stress of Styrene Vapours

This study examines the effects of styrene vapours in a mixture with air on the physiological response and anatomical changes of winter wheat cv. "Tonacja" seedlings. Seven different concentrations of styrene vapours (71, 142, 285, 570, 1,140, 2,280, and 4,559 mg.m(-3)) were applied to germinating seeds and growing wheat plants. At the lowest styrene concentration, a stimulating effect on the wheat plants was observed. However, styrene vapours inhibited germination and development of plants at higher concentrations, ranging from 570 to 4,559 mg.m(-3). Starting with a concentration of 570 mg.m(-3), a distinct reduction of the height of plants and the yield of dry matter was observed. Additionally, the number of stomata on the leaf surface decreases and an inhibition of assimilation and water use efficiency in the photosynthesis process were also observed in plants exposed to higher levels of styrene vapours. At the styrene concentration of 2,280 mg.m(-3), the number of stomata on the leaf surface decreased about 10 times to the control sample and a strong dehydration of stomatal cells occurred. Styrene at highest concentration (4,559 mg.m(-3)) completely inhibited the germination ability of wheat seeds. These results clearly suggest that styrene vapours impaired the physiology of wheat under conditions tested.