Environmental factors and genotypic changes in lipids contribute to the winter hardiness of Norway spruce (Picea abies).

Lipids were extracted from needles of Norway spruce plants of different provenances. The plants, seeds of which were originally collected from all over Europe, were grown at two sites in England at the same longitude but one 350 km north of the other. Significant correlations were observed between monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG) ratios on the one hand and, on the other, the lowest extreme winter temperature at the original site of seed collection (EWTS).

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.

Tansley Review No. 24 Why are atmospheric oxides of nitrogen usually phytotoxic and not alternative fertilizers?

Atmospheric pollution by the oxides of nitrogen, NO and NO , can cause reductions in growth but rarely visible injury. This review considers their uptake into foliage, as well as their subsequent metabolism and physiology, and attempts to explain why these gases are often phytotoxic. The combined stresses of resisting cellular acidification, enhanced levels of nitrite (and ammonia), and the direct interference of the free radical ('N=O) with critical enzymes, reaction centres and regulatory mechanisms are thought to be the main reasons why oxides of nitrogen, especially NO, inhibit growth.