203
The ratios between the annual shoots of the main axis and the shoots of the
branches for length, diameter and number of nodes were studied in the field on natural growing trees. These three ratios were greater than 1 in both analysed provenances. The length-diameter and number of nodes- diameter ratios of the annual
shoots differed between the positions of the shoots, being in both provenances larger
in the branch than in the main axis. These evaluations indicate clear differentiation
levels between trunk and branches in terms of annual shoot morphology.
The differences observed in phenology and tested in frost resistance between
provenances and clones are indicative of the possibility of population and individual
selection in future breeding programmes. Even in Negro provenance, which has a
longer growing season, some clones resisted early frosts similarly to those of Chubut
provenance. Such traits of important adaptability and productive meaning (probably
of high heritability), combined with the fact that S. humboldtiana is able to produce
Fig. 7.12 Early frosts damage in Negro River and Chubut River clones. (a) Severe early frost
damage on the leaves and shoots of one of the Negro River clones. (b) Frost damage on the group
of Negro River clones (left) and almost no damage on Chubut River clones (right). (Photos:
L. Gallo). (c) Mean frost damage per clone and their standard errors for the Chubut and Negro
provenances
7 Araucaria araucana and Salix humboldtiana…
The ratios between the annual shoots of the main axis and the shoots of the
branches for length, diameter and number of nodes were studied in the field on natural growing trees. These three ratios were greater than 1 in both analysed provenances. The length-diameter and number of nodes- diameter ratios of the annual
shoots differed between the positions of the shoots, being in both provenances larger
in the branch than in the main axis. These evaluations indicate clear differentiation
levels between trunk and branches in terms of annual shoot morphology.
The differences observed in phenology and tested in frost resistance between
provenances and clones are indicative of the possibility of population and individual
selection in future breeding programmes. Even in Negro provenance, which has a
longer growing season, some clones resisted early frosts similarly to those of Chubut
provenance. Such traits of important adaptability and productive meaning (probably
of high heritability), combined with the fact that S. humboldtiana is able to produce
Fig. 7.12 Early frosts damage in Negro River and Chubut River clones. (a) Severe early frost
damage on the leaves and shoots of one of the Negro River clones. (b) Frost damage on the group
of Negro River clones (left) and almost no damage on Chubut River clones (right). (Photos:
L. Gallo). (c) Mean frost damage per clone and their standard errors for the Chubut and Negro
provenances
7 Araucaria araucana and Salix humboldtiana…