Improving Seed Germination and Early Growth of Caucasian Whortleberry (Vaccinium arctostaphylos L.) by Plant Growth Promoting Rhizobacteria (PGPR) and Cold Stratification

Aims: The purpose of this research was to investigate the effects of plant growth-promoting rhizobacteria and the cold stratification periods on seed germination of Vaccinium arctostaphylos. Material & Methods: The seeds were inoculated with growth-promoting bacteria, including Bacillus subtilis, Enterobacter cloacae, and Pseudomonas putida, as well as a combination (co–inoculation) of all strains. Then, they were subjected to cold stratification in a refrigerator at ۴±۱°C for ۰, ۱, ۲, ۳, ۴, and ۵ months. At the end of each period, seeds were sown in polyethylene bags (۱۵ cm × ۸ cm) containing cocopeat, perlite, and sand (۱:۱:۲) and placed in a greenhouse with temperatures of ۲۲°C and ۲۵°C and relative humidity of ۶۰% and ۷۰%, respectively. After ۴۰ days, germination percentage, germination speed, and seed vigor index (SVI) were calculated.Findings: Results indicated that bacterial inoculation and their interactions influenced germination traits. Germination percentage ranged from ۰ to ۵۸.۵۰%. Both inoculation and CS positively affected germination percentage. The highest seed germination rates (۵۷.۵۰-۵۸.۵۰%) and germination speed (۲.۲۶ n. d-۱) were observed in co-inoculated seeds with all bacteria combined and ۴ to ۵ months of cold stratification, respectively. The maximum shoot length (۲۳.۲۵ mm), root length (۱۷.۹۸ mm), and seed vigor index (۲۴.۱۲) were recorded for co-inoculated seeds with all bacterial inoculants and ۵ months of cold stratification. Conclusion: The results confirmed overcoming seed dormancy, increased seed germination components, and early seedling growth in V. arctostaphylos. Plant growth-promoting rhizobacteria are more effective when combined with cold stratification.

کلیدواژه ها:

Caucasian Whortleberry ، Pseudomonas putida ، Seed dormancy ، Vigor index