Seasonal changes in the pigments of Norway spruce, Picea abies (L.) Karst, and the influence of summer ozone exposures.

There are always significant pigment changes in Norway spruce [Picea abies (L.) Karst.] needles with time in different year classes, even through the winter, but no significant changes in current year needles occur either during summer exposure due to ozone (70 nl i ) or in the winter following. Effects of summer ozone fumigation on pigment levels, however, are very evident in 1- (and 2-)yr-old needles. These include significant decreases of total amounts of chlorophyll a and b, violaxanthin, antheraxanthin, and lutein. The only increase in pigment of 1-yr-old needles in the summer caused by ozone is that of 5, 6-epoxy-lutein; consequently, the 5, 6-epoxy-lutein/lutein ratio rises. Although traces of 5, 6-epoxy-lutein also occur in the winter afterwards, they are not significant but significant decreases in levels of chlorophylls, vioiaxanthin, antheraxanthin, lutein and β-carotene persist. The fall in chlorophyll a levels are greater than those of chlorophyll b so a significant fall in the chlorophyll a/b ratio also occurs. Similarly, the declines in amount of β-carotene are not as great as those of chlorophyll a and therefore significant increases in the ratio of β-carotene to chlorophyll a are observed. No time x treatment interactions occur after ozone fumigation of 1-yr-old needles has been stopped but time x ozone interactions are observed during fumigation in both chlorophyll a/b and violaxanthin/antheraxanthin ratios. Most pigment changes in 2-yr-old needles due to summer ozone exposure are complementary to those which occurred in 1-yr-old needles in response to ozone the summer before.