Effect of Seed Maturity and Dormancy Breakage on Improvement of Seed Germination in Tilia rubra subsp. caucasica form Angulata

This research was carried out with the aim of dormancy breakage and seed germination improvement in mature and immature seeds of T. rubra subsp. caucasica form angulata. The seeds were collected from middle altitude (500 a.s.l.) forests of Chamestan, north of Iran. Mature and immature seeds with pericarp were treated as 1) cold stratification (without pretreatment), 2) imbibed with NaOH (30%)+cold stratification. Also, mature and immature seeds without pericarp were treated as 1) imbibed with gibberelic acid (500 mg/l)+cold stratification, 2) imbibed with kinetin acid (1 mg/l)+cold stratification. The examination was performed as completely randomized design with three replications. The highest amount of seed germination belonged to mature seeds without pericarp-imbibed with pretreatments of acid (giberelic or kinetin) and also immature seeds with pericarp-without pretreatment. The highest germination speed allocated to immature seeds with pericarp-without pretreatment, and the maximum mean germination time to mature seeds without pericarp-imbibed with giberelic acid. The results of this research showed that for optimizing seed germination of this species with above mentioned provenance, the best conditions for seed germination is, immature seeds with pericarp, subjected to cold stratification (without any pretreatment).