Genotypic variation in morphology and freezing resistance of Eucalyptus globulus seedlings subjected to drought hardening in nursery / Variación genotípica en la morfología y resistencia a la congelación del Eucalyptus globulus a la sequía sometido al endurecimiento en vivero

Eucalyptus globulus Labill is one of the most planted species in Chile, because of its fast growth and superior pulp qualities. Nevertheless, the incidence of drought and frost damage immediately after planting is frequent. The purpose of this work was to study the effect of drought hardening on frost resistance and on variations in morphological traits that may increase drought resistance at nursery phase in four genotypes of E. globulus Labill. Drought hardening treatments consisted in induced water stress by watering restriction, until pre-dawn stem xylem water potentials (Psi pd) reached -0.2, -1.8 and -2.6 MPa. Two water stress-rewatering cycles were applied during 54 days of hardening. Plant and root biomasses were affected by the interaction of drought hardening and genotypes. The rest of morphological and alometrical traits were affected independently by drought or genotype. Plant height, leaf area, specific leaf area (SLA), stem, and leaf biomasses decreased with drought hardening, while collar diameter was not affected. Genotypes responded differentially to drought hardening in plant height, leaf area, SLA, and stem, and leaf biomasses. Ice nucleation temperature (INT), and freezing temperatures (FRT), and 50 percent freezing damage index of leaves (LT50) were affected by the interaction between drought hardening and genotypes. EG-13, EG-23 and EG-22 genotypes became freezing tolerant with drought hardening (-2.6 MPa). Additionally, EG-14 genotype increased its freezing resistance at -1.8 MPa. Therefore, freezing resistance levels and mechanism depend on genotype and drought hardening treatment. The success in tree breeding by genetic selection should be facilitated by improved understanding of the physiology of stress resistance development and survival during water supply limitations. The knowledge of morphological and freezing resistance dependency on the interaction between genotype and drought hardening may be useful...

Asociacion de levaduras del genero Cryptococcus con especies de Eucalyptus in Santafe de Bogota / Association of Cryptococcus sp. with Eucaliptus trees in Santafe de Bogota

El aislamiento de Cryptococcus neoformans var. gatii, serotipo B, a partir del medio ambiente se establecio inicialmente en Australia en 1989, en asocio con el Eucalyptus camaldulensis y posteriormente con E.tereticornis. Con estos hallazgos se postulo que desde alli, el hongo se ha podido exportar, por medio de las semillas contaminadas, a otras regiones geograficas, incluyendo Colombia....

Análisis del aceite esencial del eucalyptus grandis (Hill ex Maiden) / Analysis of esential oil of eucalyptus grandis (Hill et Maiden)

Se estudió la composición química del aceite esencial de Eucalyptus grandis (Hill ex Maiden), obtenido de plantas cultivadas en la Estación Experimental de Topes de Collantes, provincia de Sancti Spiritus, mediante la cromatografía gaseosa, la espectroscopía infrarroja y el sistema acoplado cromatografía gaseosa-espectometría de masas. Se determinó que el aceite esencial de E. grandis está formado por una mezcla compleja de componentes, de los cuales se identificaron 42