Effect of pre-germinative treatments on Nothofagus glauca seed germination and seedling growth

Background: Nothofagus glauca (Phil.) Krasser (Nothofagaceae, “Hualo”) is an endemic tree of the Mediterranean zone of Chile. The natural forests in this area have been severely fragmented as a result of human causes such as replacement by agricultural crops and fast-growing tree species. From 1975, these forests have declined from 900,000 ha to 145,000 ha, so it is categorised on the IUCN Red List as ‘vulnerable’. In restoring this ecosystem, efforts should focus, in part, on the propagation of quality stock. However, information on propagation systems is still insufficient. Methods: We aimed to analyse the effect of different pre-germinative treatments and sowing times on seed germination, and seedling growth and quality. The pre-germinative treatments were: (i) cold stratification; (ii) soaking in gibberellic acid (GA3) and thiourea solution; and (iii) nursery cultivation, while the sowing times were July, August and September. Results: A high germination capacity was achieved by: soaking the seeds in GA3 solution irrespective of concentration; stratifying, irrespective of period; or soaking in 7.5 mg L-1 thiourea solution, values significantly varied from that of the control treatments. The sowing time was not relevant in terms of the percentage of germination or seedling development. Stratification at 5°C for 60 days produced the best quality indices for N. glauca seedlings but no significant differences were found in any of the morphological attributes tested as a result of the pre-germinative treatments. Conclusions: The pre-germinative treatments significantly improved the germination and seedlings growth of N. glauca. Cold stratification at 5°C for 60 days is recommended as it produced suitable seedlings for field establishment. Gibberellic acid and thiourea did not produce important effects on seedling growth. Our results suggest the presence of endogenous physiological dormancy of the N. glauca seeds. The results of this study provide important information on propagation and nursery techniques of N. glauca, which can be used in restoration programmes.