Lipid composition of pine needle chloroplasts and apple bark tissue as affected by growth temperature and daylength changes. 2. Glycolipids, neutral lipids and chlorophyll

Glycolipids, neutral lipids and chlorophyll of chloroplasts of pine needles ( Pinus sylvestris L.) and apple bark tissue ( Malus sylvestris Mill. cv Golden Delicious) were determined in a series of experiments in which growth temperature and daylength were changed. Trees were exposed to 0 and 20°C and to daylength conditions of 9 and 14 h. All 16 possible combinations were studied by transfer of the trees from the original condition to each of the other conditions. There was no direct relation between cold hardiness and glycolipid composition in apple bark and pine chloroplasts, when temperature and/or daylength were changed. Glycolipid and neutral lipid composition seemed to be strongly determined by the sequence of the imposed sets of daylength and temperature, and the effects of these factors on lipids strongly differed from that on cold hardiness. When the treatments were given in seasonal order, the corresponding changes in chloroplast glycolipids matched those reported in the literature for needles collected in the forest the year around. Glycolipid synthesis could well be under phytochrome control.