Growth Changes of Apple Seedlings in Response to Simulated Acid Rain1,2

in Journal of the American Society for Horticultural Science
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  • 1 Department of Pomology and Viticulture, New York State Agricultural Experiment Station, Geneva, NY 14456


In a greenhouse experiment, Malus hupehensis (Pamp.) Rehd. seedlings were treated weekly with simulated acid rain solutions ranging from pH 2.25 to pH 7.0. Necrotic lesions developed on leaves at pH 2.25 and pH 2.50 immediately after the first application at the 8-node stage. Following the 9th weekly application on seedlings with 23 to 26 nodes, lesions developed at pH levels up to 3.25. At final destructive harvest, 20% of the leaf area at pH 2.25 and 8% of the leaf area at pH 2.50 was injured. Significant growth reduction occurred at these 2 pH levels. Regression analysis indicated extensive growth inhibition at <pH 3.0, no growth inhibition around pH 3.5, some inhibition between pH 4.5 and pH 5.6, and normal growth at pH 7.0 in comparison to the unsprayed control. Growth was negatively correlated with lesion formation at 3 destructive harvest dates. Relative growth rates were reduced only at pH 2.25 and pH 2.50 and reduction in the unit leaf rate was also observed. Lesion development continued to increase on the basal leaves through the 6th weekly application but leveled off during the final applications. Negative correlations of photosynthesis rate to lesion percentage and dry weight to lesion percentage were observed.

Contributor Notes

Received for publication February 12, 1982. Approved by the Director of the New York State Agricultural Experiment Station as Journal Paper No. 3413.

The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be marked advertisement solely to indicate this fact.

The authors gratefully acknowledge the technical assistance of K.M. Stone and R.S. Johnson for help with photosynthesis measurements. We thank Warren Knapp for providing local precipitation chemistry data.

This work supported in part by a subcontract from the EPA-NADP Acid Precipitation Program (EPA Cooperative Agreement #CR806912-01-0 with North Carolina State University).