DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/1966 str. 110     <-- 110 -->        PDF

HETEROSIS


Genus Pinus: Is exhibited in the hybrid P. strobus x griffithii, which is also
resistant to blister rust. The hybrid P. densiflora x P. thunbergii also has
hybrid vigor; data are not available on its rate of growth in Japan. Other
hybrids with this characteristic include P. nigra x P. resinosa, P. thunbergii
x P. nigra, P. ponderosa x P. engelmannii, P. ponderosa x P. montezumae,


P. echinata x P. rigida, P. contorta ssp. latifolia x P. banksiana. M o u 1 o-
p o u 1 o s and Bassiotis (37) established that the hybrid betwen P.
halepcnsis and P. brutia grows faster than either parent at the age of 9 year?.
Genus Abies: In Bavaria two hybrids display intensive luxuriant growth
(47). A cross Abies Veitchü x A. alba, 11 years old, is 205% taller than its
female parent and 301% taller than its male parent. A hybrid A. concolor x


A. Veitchii is taller than its female and male parent by 162% and 204%
respectively. Rohmede r stresses that the intensive growth of the hybrid
not only depends on the combination of suitable species but also on the
individuals used in crossing. Besides, in hybrids of fir high resistance to cold
is more important than growth rate.
In the genus Picea the hybrids displaying heterosis are: P. glauca x P.
engelmannii and the reciprocal, and the hybrid between the species P. glaucaand P. jezoensis. According to our investigations (56), the cross between Omorika
spruce and Sitka spruce surpasses Omorika spruce in growth at the age
of 5 years. According to Langne r (33), a 2-year-old hybrid between these
two species exhibits a heterotic effect, while the older hybrids from a previous
experiment do not show this character.


Genus Larix: The best known is the hybrid between L. decidua and L.
leptolepis, which was first established in Scotland. Many papers have been
published dealing with the hybridization of these two species. Thus for instance
in Denmark, L a r s e n (34, 35) carried out extensive investigations on
hybridization between the mentioned two species. In Germany we may
mention Dimpflmeier (11), Langner (3,0 32) and Go the (20). In
Yugoslavia Vidakovi ć (53, 54) works on the hybridization of larch. In
all cases it was shown that the hybrid larch is strongly heterotic, and in
addition is resistant to the canker. The hybrid between the Siberian and
Japanese Larch is interesting for the Scandinavian countries and the


U.S.S.R. Albenski j (1, 2, 3) established the phenomenon of heterosis
in this hybrid as well as in the hybrid between the European and Japanese
Larch. According to Rohmede r (47), the hybrids L. decidua x L. gmelini,
and L. decidua x L. gmelini var. principis Ruprechtii also exhibit the phenomenon
of heterosis.
In the genus Pseudotsuga, C h i n g (8) obtained by crossing P. taxifolia
x P. macrocarpa hybrid plants which at the age of 2 years were larger than
their parents.


The genus Populus has the well known characteristics that may of its
species are easy to cross and that the pure species as well as the hybrids are
easily propagated from cuttings. Many natural crosses are well known in
poplars. Thus, for instance, several very valuable clones such as 1-214 and
1-156 were selected in Italy from spontaneous crossess between P. deltoides
and P. nigra. These clones are successfully grown in Italy and the neighbouring
countries. We can be certain that these clones possess hybrid vigor