Conductivity test for Scots pine (Pinus sylvestris L.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) seeds vitality assessment

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