Sustainable methods are required to protect newly planted tree seedlings from insect herbivore attack. To this end, here Norway spruce (Picea abies (L.) Karst.) seeds were treated with 2.5 mM nicotinamide (NIC), 2.5 mM nicotinic acid (NIA), 3 mM jasmonic acid (JA) or 0.2 mM 5-azacytidine (5-Aza), and 6-month-old seedlings grown from these seeds were planted at a reforestation area in central Sweden. Attack by pine weevils (Hylobius abietis) was reduced by 50 per cent by NIC treatment, 62.5 per cent by JA treatment and 25 per cent by 5-Aza treatment, when compared with seedlings grown from untreated seeds. Watering 18-month-old spruce seedlings with 2 mM NIC or 2 mM NIA did reduce attack during the first season in the field by 40 and 53 per cent, respectively, compared with untreated plants. Girdling was also reduced by the different treatments. Analysis of conifer seedlings treated with 5-Aza points at a possible involvement of epigenetic mechanisms in this defensive capacity. This is supported by a reduced level of DNA methylation in the needles of young spruce seedlings grown in a greenhouse from NIC-treated seeds. Seed treatment for seedling defense potentiation is simple, inexpensive and also a new approach for forestry with many potential applications.
The low availability of nitrogen (N) is believed to be one of the major limiting factors of forest regeneration inIceland and frequently under Boreal conditions. Lutz spruce (Picea x lutzii Littl.) seedlings were nutrient loadedusing four fertilization regimes in the end of nursery rotation in autumn 2008 and planted in the following spring,with or without a single dose of fertilizer, on two treeless sites in N-Iceland with contrasting soil fertility.Measurements were made after one growing season. The highest loading level without additional field fertilizationincreased new needle mass by 122% and 152%, for the poor and more fertile site, respectively. The highest loadinglevel with field fertilization increased new needle mass equally, by 188% and 189%, for the poor and more fertilesite, respectively. Retranslocation of N, from old needles to current needles, increased with more loading.However, it was clear that nutrient loading could not replace field fertilization, as the seedlings generally showedan additive response to field fertilization and nutrient loading; doing both always gave the best results in seedlingperformance. As the study only covers field establishment during the first year, the long-term effect of nutrientloading of Lutz spruce cannot be predicted. However, it was concluded that loading might provide an additionalinput for faster plantation establishment during the first growing season after planting.
Small conifer seedlings (mini-seedlings) are less damaged by the large pine weevil Hylobius abietis (L.) (Coleoptera: Curculionidae) compared to conventional seedlings. Chemical difference between the seedling types is one possible explanation for this phenomenon. In the present paper, the emissions of volatile organic compounds (VOC) of 7- to 43-week-old Norway spruce [Picea abies (L.) Karst.] seedlings were analyzed. Collection and identification of the volatiles was made by solid phase micro-extraction and gas chromatography mass spectrometry (SPME–GC–MS). The enantiomers of α-pinene and limonene were separated in a two-dimensional GC (2D-GC). Most of the seedlings represented either a limonene- or a bornyl acetate-chemotype. Only minor changes in the volatile composition of the two types of seedlings were found during the first year. Age-related changes, however, were found in the volatiles released by wounded phloem where green leaf volatiles (GLVs) and borneol were the dominated VOC for young seedling. The attractive compound for the pine weevil, α-pinene, was first detected in the phloem emissions of 18- to 22-week-old seedlings. Different storage conditions of the seedlings during the winter/early spring-phase influenced the volatile composition in the phloem. High amount of GLVs was characteristic for the 43-week-old seedlings stored in naturally changing outdoor temperature, but not present in the seedlings winter-stored at a constant temperature of −4 °C. The possible role of these observed differences in odor emissions between seedlings of different age and physiological status for the feeding preferences of the large pine weevil is discussed.
Försöket visade på mycket god överlevnad för plantor odlade i såddrören, Tubesprout™. Efter två år var överlevnaden för dessa 91 % för tall och 79 % för gran. För miniplantorna odlade i Jiffy varierade överlevnaden efter två år mellan 84 (tall) och 64 % (gran). Lägst överlevnad efter både det första och andra året hade de större referensplantorna. Av dessa levde 67 % av tallplantorna och endast 45 % av granplantorna. Bidragande till den goda överlevelsen hos Tubesprout™-odlade plantor var få snytbaggeskador och nästan inga skador av torka. Det andra miniplantsystemet, Jiffy 18, klarade snytbaggen nästan lika bra som Tubesprout™, men drabbades istället av stora avgångar beroende på torka. Hylsan tycks förhindra uttorkning av plantan som annars är ett stort problem vid plantering på torra marker av små plantor. För de äldre täckrotsodlade referensplantorna var den mesta plantdöden orsakad av kraftiga snytbaggeskador. Granen var värst drabbad med drygt 50 % snytbaggedödade plantor efter två år, medan den plantavgång hos tall som var orsakad av snytbagge var 26 %. Några plantor som stod i Tubesprout™ på försöksytan blev dock uppryckta, sannolikt av kråkfåglar.
Swedish forest tree nurseries produce approximately 300–350 million seedlings annually for outplanting. Most seedlings (80%) are containerised i.e. they are produced in small containers or pots that are filled with a growing media.