Changing carbohydrate profiles in shortleaf pine (Pinusechinata) after prolonged exposure to acid rain and ozone

Abstract

Shortleaf pine (Pinusechinata Mill.) seedlings grown in open-top chambers were exposed to several combinations of ozone (near zero, ambient, 1.7 × ambient, or 2.5 × ambient) in conjunction with acid rain (pH 3.3, 4.3, or 5.3) starting in August 1988. Needle samples from the first (89-1) and third (89-3) flushes of the 1989 growing season were analyzed for their glucose, sucrose, total reducing sugars, and starch contents. For the 89-1 flush (current-year needles), no differences in glucose, sucrose, or starch contents were observed among the various ozone exposures during 1989. However, needles exposed to 2.5 × ambient ozone exhibited higher levels of total reducing sugars compared with other ozone exposures for most of 1989. High H+ concentration (pH 3.3) increased glucose content (compared with pH 4.3 or 5.3) in the September sampling only. No significant differences were observed among ozone treatments for the total reducing sugars, glucose, or starch contents of the 89-3 flush (previous-year needles) for most of the sampling periods in 1990. However, the sucrose content was lower in needles receiving 2.5 × ambient ozone compared with other ozone exposures. Although high H+ concentration (pH 3.3) appeared to affect some carbohydrate components, there was no general trend observed.