by
C. Pérez Saavedra 38
The mesomorphic zone of Chile is one of the country’s 27 biodiversity “hot spots”. It hosts, among others, a forest ecosystem unique in the world: the Roble-Hualo forest type, also known as maulino forest, stretching between 35° 05’ and 36° 50’ S. This forest is the only Nothofagus formation growing in a typical Mediterranean climate, in a zone that hosts the highest number of endemism and rare endangered species of the country. It is also a centre of high variability for Nothofagus, and several species including ruil (Nothofagus alessandri Espinosa), huala (Nothofagus leonii Espinosa) and hualo (Nothofagus glauca (Phil.) Krasser) can be found. The genus Nothofagus belongs to the family Fagaceae. In Chile, this family is composed by 9 species and one natural hybrid N. leonii (a natural cross between N. obliqua and N. glauca).
This ecosystem is under various threats. Long summer draughts (rain falls in form of heavy precipitations during the few winter months) contribute to the fragility of these relic stands. On the other hand, anthropic pressures (land use conversion to shifting agriculture, charcoal and firewood production and the substitution of natural stands by exotic plantations) tend to fragment and encroach on the forest. Only 0.05% of this ecosystem is represented in the State’s National System of Wild Protected Areas (SNASPE).
Species restoration programmes, including the establishment of gene banks, ex situ conservation stands or assisted regeneration in protected areas, are sometimes necessary, and rely on the availability of Nothofagus reproductive materials of appropriate genetic, physiological and physical quality in appropriate quantities. Basic knowledge of seed collection, treatment, handling and storage is a prerequisite to operational programmes. The study summarized in this paper aimed at finding the most appropriate pretreatment for Nothofagus alessandri, Nothofagus leoni, and Nothofagus glauca seed to obtain the highest capacity and germination energy. It will also analyze other specific aspects in order to:
• determine whether the application of pretreatment gives better results than no pretreatment (controls);
• analyze results of germination through the application of 2 chemical compounds that have shown favorable results in other species of Nothofagus. These compounds are giberelic acid (GA3) and Tiourea at different levels of concentration and different periods of exposure.
The analysis was carried out in the Chillán Seed Centre; seed was harvested during the 2002 season, in the National Reserve of Los Ruiles (35° 49’ S), Chanco, VII region. 50 seeds were sampled with 4 repeated applications for each treatment, and the seeds were distributed on a random base. The seeds were raised in germinators. Although treatments differed slightly between species, the main factors studied were:
• Stratification in wet sand at 2-4ºC for 2 to 8 weeks (treatments E);
• immersion in Tiourea (from 2 to 6 days) at different concentrations (from 05% to 1.0%) (T); and
• immersion in giberelic acid GA3 for 2 to 3 days (at concentrations between 200 and 600 ppm) (G).
Two variables were calculated:
• Relative germinative capacity (RGC): = % of germinated seeds out of total number of viable seeds
• Average time (AT) which measures the germinative energy (GE), and the average time that seeds take to germinate.
Nothofagus glauca
• The treatment with low concentration giberelic acid (200 ppm) was the most appropriate to improve both RGC and AT, although all pretreatments lead to better results than controls without pretreatment.
• The most appropriate treatments to increase the germinative capacity were immersion in giberelic acid at 600 and 200 ppm (giving a success rate of 72%). The best results in terms of average time variable were obtained by a 6 week stratification associated with a 3 day immersion in giberelic acid at 200 ppm (13.3 days).
Nothofagus alessandri
• Best results was obtained through six-week stratification, giving a relative germinative capacity (RGC) of 72.7% and a 58.0 % germinative energy (GE) on day 16.
• The average germination time was 16 days. Only if 2 pretreatments were applied, would 70% have germinated during that time.
Nothofagus leonii
• The best pretreatments consisted in immersion in giberelic acid at 200 ppm, giving a RGC of 87.5% and a GE of 83.3%, followed by higher giberelic acid concentrations (400 ppm). for 2 days, with 85.4% of relative germinative capacity and germinative energy.
• The average germination time was 16 days.
These results are the first step towards the finalization of comprehensive seed collection and handling protocols for each individual species, with the final objective to produce the highest amount and the best quality of plants for future ex situ conservation activities. They will hopefully contribute to a better protection, management, conservation and use of the unique Mediterranean Nothofagus forests.
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Donoso, C. 1974. Árboles y Arbustos Chilenos. Facultad de Ciencias Forestales, Universidad de Chile. Departamento de Silvicultura. Santiago, Chile.
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Gordon, A. G. 1979. Uso y Abastecimiento de Semillas Forestales en Chile. Doc. de trabajo N° 16, FAO: DP/CHI/76/003. Investigación sobre desarrollo forestal. Santiago, Chile.
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Schmidt, L. 2000. Guide To Handling of Tropical and Subtropical Forest Seed. DANIDA Forest Seed Centre, Humlebaek, Denmark.
37 Received March 200
38 Forestry officer - Technical Department, Seed, Genetics and Entomology Research Centre, National Forestry Corporation (CONAF) – Chile
