Investigation of some germination characters in Prunus spinosa L. (Rosaceae) and determination of possible role of domestic goats in its germination

Some Prunus species, including Prunus spinosa L. (blackthorn plum), have fruits with a stony endocarp. It has been stated that the germination of Prunus species is long-lasting and difficult due to exogenous dormancy resulting from both this stony endocarp and testa, and endogenous dormancy which is caused by embryo itself. In this study, seed and endocarp of blackthorn plum were examined microscopically (stereomicroscopy and scanning electron microscopy), germination rate and duration of this plant were determined, and possible role of domestic goat (Capra hircus) in its germination and dispersal was investigated. Some of the ripe fruits which were harvested from different locations within the limits of Tekirdağ province were dried, and the pits were removed from some of the freshly harvested fruits. The seeds were also removed from some of these pits. Some pits were collected from goat pens in the three villages around the area where the fruits were harvested, and the seeds of some of them were removed. Size and weight of the dried fruits, pits and seeds, and strength of the pits were measured, and then they were sown in individual plugs filled with peat compost/goat dung, and left outside all winter for in vivo germination. Stereomicroscopy showed that the surface of the pits from pens was more indented, light colored and dull when compared the pits with flatter and smoother surface from nature. Significant differences were also observed in seed surfaces; surface of the seeds from nature was covered with yellow-orange seed fluid and had a moist appearance. But, the seeds removed from the pits collected from pens had a surface with a dry and dull appearance. Scanning electron microscope examinations revealed that the endocarp surface was more uniform and the lignified cells were whole in the pits from nature, while the lignified cells were fragmented and broken in the endocarp surface of the pits from pens. Germination rate was 4.18%, and the earliest germination was at 83 days. The size and weight of the germinated pits and seeds were above the mean values. Endocarp removal increased the germination rate, so that it was 3.42% for pits and 5.42% for seeds. The combined germination rate of the pits and seeds from pens (6.54%) was two-fold when compared to those from nature (3.27%), implying that goats facilitate the germination of pits and seeds by chewing and/or ruminating them. In addition, goats provide the dispersal of this plant by spitting out the pits during feeding and/or rumination. Keywords: Prunus spinosa, goat, endozoochory, germination