Effect of provenance and chemical treatments on the germination characteristics in immature seed of linden

One of the problems of propagation of lindens (Tilia spp.) is low seed germination. In this research, different treatments for stimulating the germination in immature seeds of Tilia rubra subsp. caucasica form angulata collected from middle altitude (500 m a.s.l.) and high altitude (1500 m a.s.l.) of Chamestan forests (northern Iran) were examined. In both altitudinal seed sources, immature seeds with pericarp were subjected to 1) cold stratification, and 2) imbibed with NaOH (30%)+cold stratification. Also, immature seeds without pericarp were examined as 1) imbibed with GA3 (500 mg/l)+cold stratification, and 2) kinetin acid (1 mg/l)+cold stratification. The most germination percentage (87%) allocated to non-pericarp seeds of higher altitude, treated respectively, with 1) GA3+cold stratification, and 2) kinetin acid+cold stratification. The most germination speed (6 seeds/week) belonged to seeds of with pericarp collected from middle altitude, treated respectively with 1) cold stratification, and 2) imbibed with GA3+cold stratification. The lowest mean germination time (20 days) allocated to seeds with pericarp of middle altitude (only cold stratified). Generally, even though, non-pericarp immature seeds of higher altitude, imbibed with GA3 (and kinetin acid)+cold stratification had favorable germination percentage, the immature seeds with pericarp of lower altitude (only cold stratified) represented satisfaction germination percentage along the shorter period. However, in future investigations, effect of treatments on seed vigor index and growth of Tilia seedling in order to employ the proper method for seed propagation and seedling production of this species in nursery are advised