Seedless barberry (Berberis vulgaris L. var. asperma) is a particular fruit crop that has been used extensively as a medicinal plant in traditional medicine. For the first time, chilling and heat requirements of seedless barberry for breaking of dormancy were calculated. The studied genotypes assayed were selected from Khorasan-e-Jonoobi province in the eastern part of Iran. Uniform one-year-old cuttings were obtained from the shrubs of each genotype after leaf fall and were stored at 4 ± 1 °C for 0.00 (control), 400, 700, 1100 and 1400 h. Six characters including days to the first leaf bud break, days to the first flower bud break, days to full flower bud break, leaf bud number, flower bud number and flowered bunch number were examined. In addition, chilling and heat requirements were determined. Results showed that chilling treatments had significant effects on all the measured traits. The cuttings reached a period of chilling of 1100–1400 h showed the earliest full flower bud break. The highest number of flowered bunches was observed in the cuttings treated with 1400 h chilling. All the genotypes had a chilling requirement of 1400 h. On the contrary, the genotypes were classified into two groups based on heat requirements with 2904 and 3432 growing degree hours (GDHs), however, they were not significantly differed in this regards. In conclusion, the present information can be used to advise seedless barberry farmers about which genotypes are best suited to areas with different winter conditions.
