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The level of damage to the cell membranes is a sign of aging of the seeds and a decrease in their viability. Conductometric seed testing method indirectly utilizes uncontrolled leakage of ions from seeds with damaged cell membranes to assess their viability. This involves the use of an electrical conductivity of the aqueous solution, in which seeds are soaked. The research was conducted in the years 2011−2014 and aimed at developing the methodology of evaluation of Scots pine and Douglas fir seeds by conductivity test. The aim of the study was to determine the relationship between electrolyte leakage and germination capacity of Scots pine and Douglas fir seeds. 402 samples of Scots pine seed and 90 specimens of Douglas fir seed from all over Poland were tested. The research material was both freshly harvested and stored. Scots pine seeds were obtained in the years 2008−2014, while Douglas fir – 2003−2013 as well as ones stored in the refrigerator for 15 years. Conductivity test and standard seed germination procedure of the analyzed species were used. For both Scots pine and Douglas fir, we noted that, as the electrolyte leakage rate increased, the germination capacity of the seed decreased. So we decided to test whether the vitality of the seeds was determined by means of a conductivity test. The best−fit regression model was determined and the mean expected germination capacity in the viability classes was calculated. 95% confidence intervals for the regression function were also determined. Evaluation of the viability of the seeds by means of the conductometric method is especially useful for seeds requiring a long stratification period (e.g. Douglas fir to determine the potential loss of their vitality. Although the ISTA seed evaluation rules do not require conductivity test for evaluating the seeds of Scots pine and Douglas fir, it may be applicable in situations where it is necessary to perform a rapid assessment of viability before spring sowing.
The objective of the study was to determine whether differences exist between the selected characteristics of Norway spruce cones and seeds depending on their location in the crown. The study was performed in two spruce tree stands growing under mountainous conditions (the Beskidy Mountains, southern Poland). In winter 2015, the cones were collected from 60 standing trees located in the two selected seed stands – Ujsoły and Rycerka. From each tree, the cones were collected from three crown zones: top, central and bottom differing in terms of light conditions. Two characteristics of the cones and six characteristics of the seeds were analysed. To determine quantitative and qualitative traits of seeds standard methods for seed testing were applied. Significant differences between the populations were determined for cone weight and fraction of full seeds, weight of 1000 seeds and germination capacity. The crown zones differed significantly in terms of fraction of cones in the parts of the crown and mass of one cone as well as weight of 1000 seeds, germination energy and germination capacity. Moreover, a significant intra−population variation was observed for a majority of the analysed characteristics (fraction of full seeds, weight of one cone, weight of 1000 seeds, germination energy, and germination capacity). However, no statistically significant interaction between population and crown zone was observed. A significantly lower contribution of cones in the bottom zone of the crown may affect the economic viability of the commercial harvest. On the other hand some of the important seeds traits (e.g. weight of 1000 seeds, germination energy and germination capacity) were significantly better in the bottom and central part of the crown than in the top zone. There are no justified circumstances (both qualitative and quantitative) to perform the cone harvest only from the top zone of the crown.
The use of biomass for energy purposes is an important European Union policy. In light of the restrictions concerning the use of the full−value wood from forests for energy purposes, short rotation forestry can become an alternative source of woody biomass. In this context, the most promising species is poplar (Populus spp.), productivity of which depends on various aspects such as plant spacing, cutting cycles, fertilization and cultivar characteristics. The aim of this study was to assess the possibility of cultivation of ten selected poplar clones from the section Aigeiros and Tacamahaca in short−rotation coppice in the climatic conditions of Poland. An experiment was set up in the north−eastern part of Poland in the Wichrowo Forest District. Survival, tree stocking, and biomass yield were compared. Productivity of clones was examined in five−year cutting cycle. The highest dry biomass yield (7.8 t/ha/yr) was achieved by the clone 'Hybrida 275'. In contrary, the biomass yield of the worst clone ('AF−8') amounted to 2 t/ha/yr. Some other Italian clones, such as 'AF−6' and 'MON' were not able to adapt to the local conditions at all and were excluded from the experiment. Because of the need to implement the full economic analysis of short rotation poplar plantations, it would be important to study propagation ability of certain currently studied varieties of poplar in subsequent rotations and with different production cycle period length up to the end of biomass production on a given plantation. Resistance to diseases of energy poplar plantations should also be researched.
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