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Chilgoza pine (Pinus gerardiana Wall.) is an important but endangered tree species in Afghanistan. Due to poor natural regeneration, seed-related dormancy and anthropogenic factors, the IUCN put this species on the red list. Therefore, this study was undertaken to investigate the effect of growing medium and polybag sizes on seed germination and seedling growth. In this study, four growing media of soil (So), compost (Co), forest soil (Fs) and sand (Sa), viz., M1 (So + Co + Fs); M2 (Fs + Co + Sa); M3 (So + Fs + Sa); and M4 (Sa + Co + Fs) and three polybag sizes including P1 (16 cm×16 cm), P2 (18 cm×18 cm), and P3 (21 cm×26 cm) were used and arranged in the frame of 4×3 factorial design to assess their effects on germination and seedling growth. The results revealed that among different growing media treatments, higher germination and seedling growth parameters were observed on treatment M4 (Sand + Compost + Forest Soil). Seedling growth parameters were significantly affected by polybag size, and the highest seedling growth parameters were obtained for Large Polybag size (P3).

Chilgoza is currently propagated only by seed, which shows very low and uneven germination, and slower seedlings growth that causes poor natural regeneration. Therefore this study was undertaken to investigate the effects of gibberellic acid and sowing media on seed germination and seedling growth. Two factors i.e., sowing media (three media with various proportions of soil, sand, and animal manure) and GA3 (0, 50, and 100 mg. L-1) were included in the study. This greenhouse experiment was run as 3×3 factorial in frame of CRD design with 3 replications. Results showed that apart from MGT (42.36 days), the higher FGP (58.66%), GI (274), GRI (75.01), and SFW (8.74gr), SDW (4.78gr), SL (219.80 mm), SVI (129192602) were obtained when seeds were initially immersed for 6 h at 100 mg. L-1 GA3 solution and then sown in the medium of equal proportions of soil, sand, and animal manure. In terms of simple effects, GA3 concentrations had a significant effect on the vegetative growth of seedlings, whereas media effects on seed germination were highly significant which means that chilgoza seed contains sufficient amount of gibberellin for germination and thereafter is reduced during seedling growth stages. The results also revealed that the vegetative growth response of the seedling to the concentrations of GA3 had a significant linear response but response of FGP and MGT against GA3 concentrations were significantly quadratic i.e. the use of GA3 concentrations can stimulate the growth of seedlings. Overall the results showed that the media had obvious effect on FGP and MGT which may be due to nutrients and ventilation. On the other hand, as the highest concentration of GA3 increased the vegetative growth of the seedling, so additional use may be necessary over time. In light of the results, it is suggested that GA3 in addition to media may be used for betterment of chilgoza seed germination and subsequent seedling growth.