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An inoculation technique to create ectomycorrhizal symbiosis in 1.5-year-old Norway spruce (Picea abies (L.) Karst.) container seedlings was tested. The mycelia of ectomycorrhizal fungi (EMF) – Tylospora asterophora, Piloderma olivaceum, and Cenococcum geophilum – each grown in a silica dioxide powder carrier, was mixed with a conventional low-humified Sphagnum peat at the time of sowing. Seedlings were grown in four growth media: (1) conventional peat; (2) conventional peat mixed with sterile carrier; (3) conventional peat mixed with carrier containing T. asterophora and C. geophilum, (4) conventional peat mixed with carrier containing P. olivaceum and C. geophilum. The seedling development and EMF colonization was followed during the nursery production. Further, seedlings grown in the four media were planted on a former nursery field, and their development was observed for three years. At the end of the nursery production phase, there were no differences in the seedling height or stem diameter between the growing media. The colonization degree by the introduced EMF was low. The height growth of the seedlings inoculated with T. asterophora + C. geophilum was 16% higher during the first growing season after out-planting compared to seedlings grown in the conventional peat medium, but the effect was transient. At the end of the out-planting experiment, the seedlings grown in conventional peat had the highest proportion of healthy and lowest proportion of dead seedlings. The results emphasize the importance of the growing media for seedling quality and out-planting success. The tested inoculation technique was ineffective in creating substantial levels of EMF colonization.

Norway spruce cone crops in individual trees from two seed ripening years 2012 and 2014 were studied. Data were collected from five stands in southern Finland, managed by single-tree selection harvests since the 1980s. The upper third of living crown of each individual tree was photographed for digital cone counting with image analysis. The average number of cones per tree for trees bearing any cones was 92 in 2014 and 66 in 2012. Highest cone numbers found per individual tree were 526 in the year 2014 and 364 in the year 2012. Of all trees studied, 55.5% produced cones during both years, 9.6% produced cones once and 34.9% did not produce cones in 2012 or 2014. The number of cones per tree in 2014 was positively correlated with tree diameter at breast height and the presence of cones (at least twenty) in that particular individual two years earlier and negatively correlated with local basal area. The quality of the seed crop in 2014 as determined in two of the stands was poor. Based on X-ray analyses, 44% of seeds were empty, 29% were damaged by insects feeding on seeds (Plemeliella abietina or Megastigmus strobilobius) and only 25% were full and capable of germination. The results have implications for management practices in uneven-aged Norway spruce stands. It is suggested that at each harvest entry, some large, prolific trees should be retained in order to increase the total number of seeds produced in a stand to enhance regeneration and the recruitment of new seedlings.

Scots pine (Pinus silvestris L.) cone and seed water contents were analyzed in two consecutive seasons during maturation stage in the autumn and in January and March before seed dispersal. Cones with different water contents were subjected to 2 h of freezing at −30 °C, and seed viability and laboratory germination of seeds from individual cones after treatment were analyzed. Seed water content could be well predicted with the measurement of the cone water content, and the general relationship between these two could be described with a generalized logistic function. On average, the water content of cones was 5%–10% units higher than the seeds inside them. The higher the cone water content at the onset of freezing treatment, the higher the proportion of seeds with apparent damage (based on visual inspection of seeds using X-ray images) in that particular cone. High water content in cones also resulted in decreased germination after freezing treatment. The critical cone water content for 50% germination after freezing at −30 °C was approximately 31.3% (fresh mass basis). This corresponds to 21.6% water content in seeds.

Norway spruce (Picea abies (L.) Karst.) seed is collected from both forest stands after final felling and from seed orchards. To produce high-germinability seed lots that are easy to use in nursery sowing machines, empty, insect-damaged, and other poor-quality seeds are culled. Sorting is done typically by weight or size. Previous studies of conifer seed have indicated wide variation in seed weight between individual trees or clones. However, the intratree or intraclone variations have rarely been taken into account, and intracone variation in seed weight has not been examined. We collected cones from a forest stand and from a clonal seed orchard in central Finland. Each seed from each cone was extracted, weighed, and x-rayed to assess their quality. Trees and clones differed in terms of the proportions of different quality seed. Variance component analysis showed that the intracone variation explained a larger proportion of the total variation in seed weight than did the intercone/intertree or interclone variations. Thus weight-based seed sorting has less effect on the genetic diversity of a seed lot than previously believed. We also conclude that the large differences in proportion of full seed among trees and clones impact the contribution of genotypes in seed and, eventually, in seedling lots.

Hyperspectral and thermal lifetime imaging were used to assess spruce seed quality.Viable, empty and infested seeds were resolved with high accuracy with both methods.400-1000nm data was not as informative as 1000-2500nm and thermal decay data.Classification of 93% accuracy was obtained using three wavelengths in SWIR range.The results suggest that high-throughput spruce seed quality testing is possible. The quality of seeds used in agriculture and forestry is tightly linked to the plant productivity. Thus, the development of high-throughput nondestructive methods to classify the seeds is of prime interest. Visible and near infrared (VNIR, 400-1000nm range) and short-wave infrared (SWIR, 1000-2500nm range) hyperspectral imaging techniques were compared to an infrared lifetime imaging technique to evaluate Norway spruce (Picea abies (L.) Karst.) seed quality. Hyperspectral image and thermal data from 1606 seeds were used to identify viable seeds, empty seeds and seeds infested by Megastigmus sp. larvae. The spectra of seeds obtained from hyperspectral imaging, especially in SWIR range and the thermal signal decay of seeds following an exposure to a short light pulse were characteristic of the seed status. Classification of the seeds to three classes was performed with a Support Vector Machine (nu-SVM) and sparse logistic regression based feature selection. Leave-One-Out classification resulted to 99% accuracy using either thermal or spectral measurements compared to radiography classification. In spectral imaging case, all important features were located in the SWIR range. Furthermore, the classification results showed that accurate (93.8%) seed sorting can be achieved with a simpler method based on information from only three hyperspectral bands at 1310nm, 1710nm and 1985nm locations, suggesting a possibility to build an inexpensive screening device. The results indicate that combined classification methods with hyperspectral imaging technique and infrared lifetime imaging technique constitute practically high performance fast and non-destructive techniques for high-throughput seed screening.

We studied the effect of soak-sorting Norway spruce ( (L.) H. Karst.) seeds on emergence, development and quality of container seedlings in two commercial seed lots. The seeds, separated by soaking into bottom and surface fractions, were sown in June, and the seedlings were grown during two growing seasons under typical Finnish nursery conditions. The first summer seedlings were grown in a greenhouse and outdoors for the second, full growing season. All sunken seeds were full and viable according to radiography, whereas the floating seeds contained 2% and 13% larvae-filled and 8% and 11% anatomically immature seeds, depending on the seed lot. Seedlings grown from the bottom fraction seed emerged 2.5–3.5 days earlier than seedlings of storage dry (i.e. control) seed. Height, diameter, and shoot and root dry mass of the seedlings were affected by soaking after both the first and second growing seasons. The largest seedlings originated from the bottom fraction. The proportion of saleable seedlings was four percentage points higher in the bottom fraction than in the other seedlings. The effects of soaking found in this study are more notable than as previously reported for Norway spruce seedlings. This suggests that soaking and soak-sorting may be most useful when the growing conditions are stressful, i.e. when seeds are sown in summer rather than 1-year-old seedling crops sown in spring under the climate conditions typical of Finland.Picea abies