Mineral nutrition, carbohydrate content and cold tolerance of foliage of potted red spruce exposed to ozone and simulated acidic precipitation treatments

Abstract

Ninety potted red spruce saplings enclosed in open-top fumigation chambers were exposed to O₃ (charcoal-filtered air, non-filtered air, 1.5 × ambient, or 2 × ambient) and simulated rain (pH 3.1, 4.1 or 5.1) for two growing seasons (June to October). Foliage was sampled for mineral nutrients, total soluble sugars, and starch in September 1988 at the end of the second season of exposures. The development of cold tolerance of individual trees was assessed using the electrolyte leakage technique. Ozone and simulated rain treatments had marginal effects on mineral nutrient concentrations of current and 1 yr old foliage. Ozone did not affect foliar carbohydrate levels but the simulated rain treatments of pH 3.1 tended to depress levels of total soluble sugars and starch in 1 yr old foliage and of starch in current year's foliage. During mid to late October, the current year's foliage of trees receiving rain of pH 3.1 was less tolerant to cold than the current year's foliage of trees receiving rain of pH 4.1 or 5.1. Following the October period, trees in all three acidic rain treatments had similar tolerances to cold.