The level of injury and needle ultrastructure of acid rain‐irrigated pine and spruce seedlings after low temperature treatment

Abstract

S V\] MARY Frost injury in three Finnish provenances of acid rain-treated (pH 4 and 3) pine {Pinus svlvestris (L.)] and spruce {Picea ahies (L.) Karst.] seedlings was studied by microscopical methods. Seedlinfj-s from southern and northern pr()\-enanccs were watered for sex'en weeks \\-ith artificially acidified rain during' the hardening period in 1986. A cold treatment on the \\-inter hardened seedlings was carried out in January by lowering the temperature graduallv to --S-S°C. Afterwards the development of injury symptoms was followed visually and microscopically. The most prominent sign of freezing injury was needle discoloration. In addition, the stems and buds of the seedlings showed signs of severe injury. Under the light microscope the injury was exhibited as largened intercellular spaces and increased numbers of disintegrating cells. Diminution of the n-iembraneous structures within the cytoplasm of mesophyll cells and rupturing ot plasmalemma and tonoplast, as well as swelling of chloroplasts, were seen in damaged cells. The symptoms of freezing injury at ultrastructural le\-el differed from those found in needles exposed to air pollutants.

Long-Term Symptoms Due to Metal and Acid Precipitation Treatments in Scots Pine (Pinus sylvestris) Needles in the Subarctic

“…For other abbreviations and details, see previous year's needles in all the treatments (disintegrated ER also in C needles). Tonoplast breakdown was seen in previous year's needles in all treatments, pointing further to severe frost injury (Ziegler and Kandler, 1980;Reinikainen and Huttunen, 1989). Both vacuolation and swelling of thylakoids seem to be related to needle development and reversible to some extent (Anttonen et al, 1996;Jokela et al, 1998), because they were seen abundantly in current year's needles that…”

“…On the Kola Peninsula, the sulfur and heavy metals emitted from Monchegorsk smelters (688N, 348E) have been observed to decrease the frost hardiness of pine needles . Microscopic diagnostics of the damage to conifer needles caused by low temperatures at midboreal latitudes revealed separation of the plasma membrane from the cell wall and packing of the resulting space with electron-dense granules (Holopainen and Holopainen, 1988;Reinikainen and Huttunen, 1989). The alterations in the membraneous structures of cold-injured cells were most obvious.…”

“…The alterations in the membraneous structures of cold-injured cells were most obvious. The net-like structure of the cytoplasm typical of winter-hardened needles was lost at an early stage of the winter injury (Reinikainen and Huttunen, 1989).…”

The development of winter hardiness of pine and spruce seedlings in a simulated acid rain experiment

“…The deleterious effects of air pollutants on the cold tolerance of conifers have been reported quite recently by several authors (e.g., Davison and Barnes, 1986;FreerSmith and Mansfield, 1987 Reinikainen and Huttunen (1989).…”

The effect of long‐term ozone exposure on injury in seedlings of red spruce (Picea rubens Sarg.)

“…Later in the year there were indications of missing cells, with expansion of nearby cells. Mesophyll cells in conifers may function independently; one cell may be injured, while a neigbbouring cell remains healthy (Karenlampi & Friedland, 1988 ;Reinikainen & Huttunen, 1989). It may require a minimum number of dead cells before a lesion is visible.…”