Argan (Argania spinosa (L.) Skeels) seed germination under nursery conditions:: Effect of cold storage, gibberellic acid and mother-tree genotype

The aim of this study is to assess argan (Argania spinosa) seed germination of ten argan mother-trees after four different cold storage durations with or without gibberellic acid (GA) treatment for the purpose of establishing a simple germination procedure adaptable to various nursery situations. The beginning of germination of argan seeds which, were stored at room temperature in the absence of GA treatment, was delayed for 3.4 days in average in comparison with chilled and GA-treated seeds. Germination was as low as 35.5% and seed deterioration as well as pre-emergence seedling dumping-off was important. In contrast, either GA application or cold storage at 4 degreesC for at least one month significantly led to a two fold increase of germination attaining approximately 60% and a better control of dormancy. Indeed, average germination was even higher when both treatments were combined (79.5%), mostly because GA combined to cold storage of the seeds for longer than one month periods decreased losses due to seed fungi contamination or to pre-emergence seedling dumping-off. Final germination percentage was enhanced by cold storage for the longest periods (three months) attaining values higher than 95.0% depending on mother tree genotype.