Ethylene production by potato, radish and soybean leaf tissue treated with simulated acid rain

Abstract

Solanum tuberosum cv. ‘Norland’, Raphanus sativus cv. ‘Cherry Belle’ and Glycine max cv. ‘Amsoy 71’ were treated with simulated acid rain solutions of pH 2.8, 3.8, 4.6 and 5.6. Two treatment durations were used: 1-hr/day for a single day, or 1-hr/day for three consecutive days. There was also a ‘no rain’ treatment. Petioles of excised leaves were immersed in 2 ml of 0.5 mM 1-aminocyclopropane-1-carboxylic acid (ACC) and 200 mM NaHCO 3 in the base of a 50 ml flask. Flasks were sealed and incubated for 24 hr in the dark. Air was sampled and ethylene concentrations quantified on a nl/g dry weight basis using a gas chromatograph fitted with an activated alumina column and a flame ionization detector. Potato leaves exhibited 1% injury after 1-hr or three 1-hr treatments. After three 1-hr treatments, radish leaves sampled exhibited 10–25% injury. No injury was observed on soybean, potato, or radish leaves at any other treatment level. No species exhibited increased ethylene production in response to 1-hr rain treatments. After multiple rain treatments, plants treated with pH 2.8 rain generally exhibited increased ethylene production; however, no direct relationship between ethylene production and treatment acidity was observed. Regardless of treatment pH or duration, radish foliage produced more ethylene than did potato or soybean foliage. Although differential ethylene production among species was observed, production in response to acid rain did not appear to be a sensitive indicator of plant stress.