CHANGES IN ENDOGENOUS ABSCISIC-ACID OF PLANTS EXPOSED TO NITROGEN-DIOXIDE

Soybean (Glycine max L. Merrill) cv. Williams and black turtle bean (Phaseolus vulgaris L.) cv. Domino plants were exposed to 0.0, 0.025, 0.05 and 0.1 μ1-1 nitrogen dioxide (NO2) in a controlled environment. The amount of abscisic acid (ABA) in leaves was measured using an enzyme-linked immunosorbent assay. At 0.025 μl NO2 there was no change in ABA levels, however, on exposure to 0.05 and 0.10 μl 1-1 NO2, a significant increase in ABA was observed. No foliar injury took place at any level of exposure. Photosynthesis of black turtle leaves increased but stomatal resistance was reduced on exposure to 0.10μl 1-1 NO2. © 1990.