Effects of environmental factors on seed germination and seedling establishment in bilberry (Vaccinium myrtillus L.)

Abstract The bilberry ( Vaccinium myrtillus L.) is a spontaneous dwarf shrub with potential for national and international markets due to food and medicinal uses of its fruits, being considered an important source of sugars, antioxidants, vitamins and minerals. Request for bilberry fruits are on the rise, but the land area covered in bilberry bushes and locally collected berries have declined in Central Italian Apennine regions in recent last decades. The objective of this study was to assess the most suitable conditions for in vivo and in vitro seed germination in order to improve the reproductive performance of this species under artificial and controlled environments. Freshly matured bilberry seeds were tested for germination before and after cold stratification and air-room storage under different light conditions and temperatures. Seeds were then in vivo and in vitro germinated on different soil types and culture media. Fresh seeds showed a better germination capacity (76%) than stratified ones, being 16-h photoperiod and air temperatures of 22.5 °C the optimal conditions for germination. At 25 °C the germination rate decreased to 66% and very few seeds (8%) germinated at 15 °C. Darkness always had a negative influence on the germination capacity. However, after cold stratification germination increased significantly at 15 °C, both in light (51%) and darkness (24%); thus, seeds of this species are conditionally dormant at maturity. Although the effect was different depending on temperature and light condition, cold seed stratification had an overall negative effect on all the considered germination parameters, and seed viability was strongly reduced after storage at room temperature for 90 days. Soil type and culture media did not significantly affect the final germination percentage (≈62 and 78%) in the in vivo and in vitro trials performed on fresh non stratified seeds, respectively. Nevertheless V. myrtillus turf ( in vivo experiment) and modified MS medium ( in vitro experiment) gave rise to the most germination in the shortest time. Temperature proved to be the most influential physical factor on bilberry seed germination. Seedlings obtained from in vivo experiments showed good development.