SEASONALITY OF ECTOMYCORRHIZAS IN NATIVE AND NURSERY CULTIVATED NOTHOFAGUS NERVOSA (RAULÍ) INDIVIDUALS: PRELIMINARY RESULTS

FERNÁNDEZ NATALIA; FONTENLA SONIA; GALLO LEONARDO; MARCHELLI PAULA

Buenos Aires, Argentina

Congreso; Congreso Forestal Mundial; 2009

Nothofagus nervosa (Raulí) is an ecologically and economically important species of South American forests. Due to its high quality wood this specieswas overexploited, what caused a drastic reduction of its natural distribution. This situation led to the implementation of conservation and domestication programs. Tree domesticationrefers to how humans select, manage and propagate species in order to increase its growth rate, disease resistance or wood quality. Among the aspects that should be considered in these programs are the mycorrhizas, a mutualistic association which improves plant growth and nutrient uptake. The survival and development of different tree species are usually dependent on ectomicorrhizas (ECM). Consequently, nursery inoculation with suitable ECM can be important for the successful establishment of outplanted seedlings during domestication programs. The general objective of the project is to analyze the abundance and diversity of ECM in N. nervosa, to compare them between native and nursery cultivated individuals and to select some ECM strains which would have significant application in domestication processes. The particular aim of this work was to quantify the percentage of root tips colonized by ECM and to evaluate its seasonality in native seedlings, young and mature individuals and in young nursery cultivated specimens. In spring 2007 and autumn 2008, five trees of each category were randomly selected from a native forest and from two different field trials: one of them established within the native forest and the other under a Pinus plantation.Seedlings were entirely removed and the rest of the plants were sampled by taking 3 soil cores per tree. Roots were sieved from the soil cores, carefully washed and then ECM were quantified. ECM were present in every sample and different morphotypes were observed. More than 90% of the root tips examined per plant in the native forest had ECM. There were no significant differences among plant categories. Young nursery cultivated individuals coming from the field trial under the Pinus plantation showed a significantly lower colonization (~70%). No seasonality was observed in the percentage of colonized tips. However, it might be possible that different plant categories have different ECM morphotypes or that abundance and composition of taxa changed throughout the seasons, but these facts need to be further studied. This work constitutes the initial step in the study of ECM in N. nervosa and provides the basis for further investigations related to their possible application in domestication programs, such as the influence of ECM inoculation on seedling survival and growth after planting in the field.