The aim of the study was to investigate the effect of four packing methods on the field survival and growth of seedlings and transplants of Scots pine (Pinus sylvestris L.) stored over the winter in a cold-storage cellar. The following sorts of plants were used: one-year-old seedlings (1+0) grown in a plastic greenhouse, two-year-old (2+0) open grown seedlings and three-year-old open grown transplants. These plants were stored in open wooden boxes, in sealed plastic bags, in boxes with wet peat on the bottom and in plastic-laminated paper bags.
The control plants were of the same types and were kept in a nursery over the winter. The storage was carried out in a mantle-chilled cold-storage from October 1966 to May 1967. The temperature in the cold-storage was kept around -2 °C and the relative humidity of the air over 90%. The water content of a randomly selected sample plants showed no increase in water deficit after the storing. Part of the seedlings were transplanted in the nursery and the rest were planted in a clear-cut area. A number of the latter plants were treated with an insecticide (1% Intaktol, which contains DDT, Lindane and dieldrin) before planting. All the experiments were examined after one growing season and the planting experiments the next fall.
The transplants (2+1) in the nursery, and in the forest had survived and grown better than the seedlings. In the nursery the 1+0 seedlings survived and grew better than the 2+0 seedlings. There was no difference in mortality between the seedlings. After the first growing season occasional significant differences between the packing methods were observed, but they disappeared during the second growing season. Thus, all packing methods proved to be as successful as the control method without winter storage.
Transplants were more often attacked by the large pine weevil (Hylobius abietis L.) than the smaller seedlings. The damage, however, was considerably greater on the seedlings because of their lower resistance. No significant differences in the Hylobius-attack between the packing methods could be observed. The Intaktol-treated plants were as often attacked as the untreated ones, but the damage was slighter on the treated ones.
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