Seed traits, seed viability and germination rates of seeds collected from 12 natural Juniper (Juniperus communis) populations in the UK, 2023-2025

Berries were collected from populations in fall 2023, weighed, and inspected for parasitism. Seeds were extracted with a food processor; filled and empty seeds were separated using the float test, then surface sanitized and dried. Dried seeds were weighed and stored at 4 degrees C until used. Seeds were then treated with one of two different pretreatments, consisting of soaking them in water or a 1% Citric Acid solution for 48 hours. A Control group was also included that was not pretreated. Next, seeds were subject to one of 4 different thermal stratification treatments: A warm stratification followed by a cold stratification; just a warm stratification; just a cold stratification; and a control without a stratification treatment. Germination was then monitored for over a year, and the differences among seedlots, populations and regions of the UK were quantified.
Additional seedlot quality and seed viability data were also collected for all 60 seedlots included in the germination trial. The field cut test (the proportion of seeds that are visibly filled with healthy embryonic tissue when bisected), the estimated numbers of filled and empty seeds from the float test, tetrazolium chloride (TZ) staining and X-ray viability are each applied to each seedlot. These results are then compared and contrasted to evaluate their relative accuracy and precision.

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