Greenhouse-grown plants of Zinnia elegans Jacq. were exposed to simulated sulfuric acid rain 30 minutes per day twice a week for 6 weeks at pH 2.8, 4.0, and 5.6. Injury occurred primarily to older, mature leaves and cotyledons at pH 2.8 and 4.0 and to ray flowers at pH 2.8. Plants supplied with higher levels of Hoagland’s nutrient solution grew more rapidly, contained greater quantitities of foliar K, P, and Ca, and exhibited more foliar injury after exposure to acidic simulated rain (SR). Dry weight of plants given full-strength nutrient solution (highest level) was depressed at pH 2.8 and increased at pH 4.0 relative to pH 5.6. Loss of 86Rb by leaching from foliage was significantly increased at pH 2.8, but no differences in total foliar content of K, P, and Ca were detected.
Received for publication March 15, 1982. This paper is from the PhD Thesis of the senior author.
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Current address: Department of Horticulture, Auburn University, AL 36849. The assistance of H. B. Tukey, Jr., and the Department of Floriculture and Ornamental Horticulture, Cornell University is gratefully acknowledged.