Duration Limits on Field Storage in Closed Cardboard Boxes before Planting of Norway Spruce and Scots Pine Container Seedlings in Different Planting Seasons

Abstract

For spring plantings, conifer seedlings are usually packed in closed cardboard boxes and freezer stored over winter. Additionally, seedlings are increasingly being stored in cardboard boxes in spring, summer, and autumn plantings in Finland. The aim of this study was to determine the maximum safe duration for the field storage of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) container seedlings in closed cardboard boxes for different planting times (dates) in Nordic boreal conditions. In the first experiment, Norway spruce seedlings (85-cm3 peat plugs) were packed in cardboard boxes in August, September, or October, and, in the second experiment, in the middle of May. In the third Scots pine experiment, mini seedlings (30-cm3 peat plugs) were packed in May. In each experiment, the seedlings were stored in closed cardboard boxes in a nursery for one, three, seven, 14, and 21 days. The control seedlings were stored in open storage in the nursery. After storage, the seedlings were planted in a field. In all of the experiments, increased closed-box storage reduced the maximum photochemical yield of photosystem II (Fv/Fm) in the needles, and reduced root growth after planting. The frost hardiness was weakened in the Norway spruce seedlings that were stored in closed boxes for 21 days in August and October. In the spring experiments, prolonged storage increased the mortality of seedlings. Mortality rates were high in the autumn experiment due to the exceptionally warm and dry weather. Our conclusions, being based on the short term effects of field storage, are that conifer seedlings can be stored in closed boxes for only three days in August and about a week in September, October, and spring.

Early Field Performance of Small-Sized Silver Birch and Scots Pine Container Seedlings at Different Planting Depths

“…In certain previous studies, small-sized Scots pine seedlings have also been observed to grow at least as well, and suffer less pine weevil damage, compared to larger-sized container seedlings [6,8,9]. However, they have been found to be more prone to storage and environmental stress factors, such as drought [8,[10][11][12]. To date, small-sized Scots pine seedlings have been used in forest regeneration mainly in the humid climate of the northern parts of Nordic countries.…”

Covering Norway spruce container seedlings with reflective shading cloth during field storage affects seedling post-planting growth

“…The planting season for Norway spruce container seedlings in Nordic countries lasts from May to September (Luoranen et al 2019). Dormant, actively growing and short day treated Norway spruce (Picea abies (L.) Karst) seedlings are recommended to be planted in spring (May to mid-June), summer (June to late July) and autumn (August to September), respectively (Luoranen et al 2005(Luoranen et al , 2006(Luoranen et al , 2018Wallertz et al 2016).…”

“…In Finland, the average field storage duration of seedlings is two weeks overall during the planting season, varying from one to 49 days (Rantala et al 2003). Luoranen et al (2019Luoranen et al ( , 2020 recommend a field storage period of 1-2 weeks for dormant container seedlings, and two to four days for growing container seedlings. The recommended storage period for actively growing container seedlings is only a few days, because of their high susceptibility to drought stress (Grossnickle and Folk 2003).…”

“…Morphological attributes are fairly straight forward to measure, but physiological attributes may more accurately predict the post-planting growth and survival of the seedlings (Grossnickle and MacDonald 2018). The same attributes can be applied to define the field performance after field storage, but the results are rather scarce (Landis et al 2010;Luoranen et al 2019).…”

Light Shock Stress after Outdoor Sunlight Exposure in Seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. Pre-Cultivated under LEDs—Possible Mitigation Treatments and Their Energy Consumption

“…Field storage in carboard boxes can significantly reduce the frost hardening and increase the seedling mortality [20]. Recent studies in Finland showed that the safe duration depends on the weather conditions and recommended only three days in summer and about a week in spring and early autumn [21].…”