Influence of biogeography and nine chemical and physical pretreatments on the germination of Juniperus phoenicea L. seeds in the Northeastern region of Morocco

Abstract

Juniperus species play a crucial ecological role by inhabiting sand dunes, thereby mitigating coastal encroachment and contributing to the stabilization and protection of these areas. However, due to excessive exploitation and seeds dormancy, this species is currently facing a continuous decline in population. To address this issue, a study was conducted to enhance the germination of J. phoenicea seeds by evaluating the impact of biogeography and various pretreatment methods. Mature red cones of J. phoenicea were collected in February-March 2021 from three different locations in northeastern Morocco, representing coastal, semi-continental, and continental populations, based on the distribution patterns of the species in the northeastern region of morocco. The gathered seeds underwent nine distinct pretreatments, including physical treatments such as mechanical and thermal shock, as well as chemical treatments involving sulfuric acid and acetic acid, alongside a control. Subsequently, the treated seeds were incubated at a consistent temperature of 20°C. Before germination, we proceeded to a viability test and found that the seed viability was 87%, although it varied depending on the geographical origin of the seeds. The cold-hot stratification had the highest seed germination rate from the semi-continental location, with a percentage of 66%, followed by the seeds of the continental location with 60%. The boiling water pretreatment recorded a germination rate of 54% in semi-continental seeds, while 51% was recorded in continental seeds. Coastal seeds had the lowest viability and germination rates regardless of the stratification applied. Due to their better germination potential, the use of continental seeds to generate seedlings of J. phoenicea in eastern Morocco should be considered. Regardless the biogeographic location, cold-warm stratification can increase germination potential at a significant rate of up to 66%.