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ŠUMARSKI LIST 7-8/1969 str. 15     <-- 15 -->        PDF

The dry matter content was determined by taking leaf samples from plants
which were nearest the average values for heights according to the treatment —

From Table 1 it is visible that the intraspecific hybrids of White Willow and
the interspecific hybrids of White and Crack Willows are superior in growth than
the intraspecific höbrids of Crack Willow. In this respect analogous results may
be recorded in one-year hybrid families and also in two-year-old ones.

The size of leaves was not measured but from the picture (where the average
leaf samples were represented) it may be seen that there exist great differences as
to the size of leaves between the hybrid families investigated. The intraspecific
hybrids of White Willow possess the smallest-sized leaves as well as the smallest
content of dry matter.

From Tables 2—7 it is visible that the concentrations of all biogenic elements
(except K) are highest in leaves of intraspecific hybrids of White Willow. In this
respect significantly higher concentrations of N, Mg and Ca were obtained in one-
year plants of White Willow and of Ca in two-year ones, in relation to the intraspecific
hybrids of Crack Willow or their interspecific hybrids.

As the values of concentration of certain elements are characteristic of intraspecific
hybrids of White and Crack Willows and their interspecific hybrids, the
authors consider that the determination of the nutrient content in leaves could be
used perhaps as one of the early test methods in the works of seelction and
improvement of arborescent species of Willows in respect of growth.

Between the heights and amounts of the investigated biogenic elements in the
foliage of one-year hybrid families highly significant correlation ratios were
obtained, while in two-year hybrid families these same ratios were positive —
nonsignificant (Tabs. 2—8, Graphs 1—2). In spite of the highest concentrations of
N, P, Ca and Mg in the foliage, the within-species hybrids of White Willow contained
relatively smallest amounts of the same elements in relation to the height
growth of plants.