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ŠUMARSKI LIST 1-2/1969 str. 60     <-- 60 -->        PDF

9. Wright , W. J. (1962): Genetics of Forest Tree Improvement, Rome, 399 pp.
Žuf a, L. (1963): Glavne vrste vrba, njihovo rasprostranjenje i stanište, Topola
7 (36—37), pp. 3—17.
Žufa, L. (1963): Oplemenjivanje i selekcija vrba, Topola (36—37), pp. 35—46.
Žufa, L. (1964): Varijabilnost i nasljednost pravnosti stabla crne topole Srednjeg
Podunavlja, Zagreb, (Dizertaciona radnja).
Žufa, L. (1965): Prilog proučavanju nasljednosti oblika debla euroameriokih
topola, Topola 9 (52—54), pp. 28—32.
Žufa, L. (1967): Zapažanja i iskustva u radu na kontroliranoj hibridizaciji
vrba stablašica, Topola 11 (61—64), pp. 37—53.


The variability and heritability of stem form (straightness and tortuosity) in
arborescent Willows was studied by the author on tree half-sib families, i. e.:

1. S. rubens Schrank (V43) X S. alba L. (V95),
2. S. humboldtiana Andre (Vise) X S. alba L. (V05),
3. S. Matsudana tortuosa Rehd. (V157) X S. alba L. (V95).
Observations as to the straightedness and tortuosity of the stem was carried
out on each particular plant in the progeny in the manner that each plant was photographed,
and the stem axis was represented in the scale 1 : 75 (Fig. 4) according
to the method described by Žuf a in his thesis (12). Figures 1, 2 and 3 represent
photographs of the stem in three parent pairs and the corresponding progenies.
In this manner it was possible to estimate objectively the range of variability of
the mentioned character within the clonal material of S. humboldtiana Andre (Vise),

S. Matsudana tortuosa Rehd. (V157), and the hybrid families, i. e. to differentiate
heritable from nonheritable variability. On the basis of splitting in the hybrid progeny,
we determined whether the parents were homozygous or heterozygous, while
the proving or rejection of the assumption as to the supposed number of hereditary
factors defining the investigated character was done with the help of the chi-
square test, in which also plants with a gentle sweep of the stem ere classified
into the group of straight-stemmed plants.
In the hybrid family of S. Matsudana tortuosa Rehd. (V157) X S. alba L. (V95)
there exists splitting into individualis with straight and toriuous stems. If we watch
the range of the variability of the observed feature (stem tortuosity) within the
clonal material of S. Matsudana tortuosa Rehd. (V157) (Fig. 3.), and the range of variability
of the same feature in the hybrid family of S. Matsudana tourtuosa Rehd.
(V157) X S. alba L. (V»s), i. e. that part of the family which consists of individuals
with tortuous stems we shall see that this range is the same with respect to the
maximum and minimum number of curvatures per plant, as well as with regard
to the length of the straight or curved part of the stem. The variability of stem
form in the mentioned family is of markedly discontinuous character. In other hybrid
families there is no splitting into individuals with straight and tortuous stems,
but with regard to the studied character the progenies display a uniformly straight
stem (Fig. 4.).

From Table 1 it is visible that the family of S. Matsudana tortuosa Rehd. (V157)
X S. alba L. (V95) possesses 16 plants with tortuous stems and 14 straight-stemmed
plants. The probability that the mentioned splitting is in the ratio of 1 : 1 amounts
to 70—8OV0, on the ground of which it can be assumed that the ratio of 1 : 1 is exact.
Regarding the discontinous variability of the investigated character and the obtained
1 : 1 splitting ratio in the progeny it may be concluded that we are concerned
with a feature of qualitative character, which is conditioned by one fair of alleles,
or monohybridally inherited. The stem tortuosity is dominant in relation to the
straightness. We arrived at the conclusion on the dominant heritability of the stem
tortuosity on the ground of the mother phenotype (S. Matsudana tortuosa Rehd.
V157) and on the basis of the presentad proof of its heterozygous constitution.