Resumen

LETOURNEAU, Federico; NAMIOT, G.; PERDOMO, M. H.  y  BASIL, J.G.. Efecto de la aclimatación a la intensidad lumínica en vivero sobre el desempeño postrasplante de plantines de Austrocedrus chilensis. RIA. Rev. investig. agropecu. [online]. 2019, vol.45, n.2, pp.216-224. ISSN 1669-2314.

The restoration of Austrocedrus chilensis forests requires seedlings that withstand difficult post-transplant conditions. During the stage of propagation in the nursery, it is common to use plastic covers and shade meshes for the production of seedlings, but this induces an acclimation to the light intensity that can affect their behavior to the transplant. The objective of this work was to study the morphological and physiological characteristics of acclimation and its consequences on post-transplant mortality and growth in the field. We established two trials, in the first one, we evaluated the changes in the biomass allocation of leaves, stems, roots, and the variations of some photosynthetic parameters, of 90 seedlings acclimated to three light levels for three years. In the second trial, we transplanted 360 seedlings in a two-factor design (micro site coverage and nursery acclimation) with two levels each factor. We fitted a set of mixed linear effects models using data of this experiment, the mortality and growth rates was estimated using one or both factors as predictor variable; and we tested the set of models with each other by a likelihood ratio test (LRT). Nursery acclimation produced changes in specific leaf area (P<0.05, n=30), in the stem / root ratio (P <0.05, n = 30); and in photosynthetic parameters such as Amax, and quantum efficiency ɸ (n=8, P<0.05). In the field experiment, we could not reject Ho that microsite levels factor is a significant predictor of mortality rate (gl=3, AIC=112.35, x2=0.00, P=1.00). The covariate plant size improved the representation of this model (P=0.001 ***, gl=4, AIC=114.11, x2=101.35), further a rank sum test shows that frequency distribution by sizes of dead plants differs by the degree of acclimation to shade in the nursery (W=80, P=0.01 *). The LRT test established that acclimation is a relevant factor to explain post-transplant growth (P<0.001***, g.l.=4, AIC=475.12, x2=7.48). The use of acclimated nursery plants at high radiation conditions improves the initial growth, and to a lesser degree affects the survival in the transplant stage. To reduce the probability of death, it is necessary to provide protection against insolation regardless of the degree of acclimation in the nursery.

Palabras clave : reforestation; restoration; ecophysiology; photosynthesis; morphology; mortality; growth; mixed linear models.