Agriculture Reference
In-Depth Information
Our studies for many years (1970-2012) revealed that seed productivity varied due
to climatic factors. Trials of clover in different agro-ecological zones led us to the con-
clusion that the optimal period of seed formation is the sum of positive temperatures
(above 10°) per vegetation 1,207-1,648° with the quantity of precipitation 445-639
mm, and in the fl owering period if seed yield reaches 1.5-1.8 q/ha, the hydro-thermic
coeffi cient (HTC) should be 1.52-3.12. Seed yield decreases to 0.5-1.2 q/ha along
with HTC growth.
Unlike steppe and foothill regions, the climate of mountains has its peculiarities.
With the ascent to altitudes 1.300-2.200 m above sea level, the short-wave ultraviolet
radiation becomes more intense, plant vitality rises, and stimulating infl uence of ul-
traviolet rays suppresses partly the negative temperature effect. Under sharp overfall
of day and night temperatures active fl owering, fruit and seed set are going. Thus, for
ripening of seeds in mountain conditions, higher HTC and consequently lesser amount
of effective temperatures are needed. It was determined on the results of these stud-
ies that with the rise of mountain elevation wild plants (unlike cultivars) had greater
percentage of set seeds in comparison with foothills. It is evident that in the mountains
low night temperature inhibited transformation of sugars to starch and other substances.
It is known that sugar impedes freezing, thanks nectar stores high quality, which is
very important for such plants pollinated by insects as clover.
Comparison of native populations, cultivars, and formed complex hybrid popula-
tions on different elevation made possible to show the environmental infl uence on
seed set. We took into consideration temperature regime of air and soil, sum of pre-
cipitation, humidity and acidity of upper layer of soil (where roots are situated). It
was found that on the same elevation, but on different soils, seed set was different.
For example, on an elevation of 900 m above sea level, seed set was 27.5 percent on
acid soil (pH 4.47) and 46.8 percent on nearly neutral soil (pH 6.45). On an elevation
of 2,000 m above sea level on two plots with pH 6.44 and 6.15 seed set of clover was
49.5 and 47.0 percent, respectively. It was also determined that the number of weak
seeds changed depending on soil acidity at a maximal proportion (above 50%) at pH
4.47. Seed set in infl orescence is higher on 9.5-27.1 percent, where acidity is 6.0 or
above that.
It was found [9] that in selection for seed productivity, it is possible to receive
positive results, using phenotypic selection on the following traits: coloration of fl ow-
ers, number of generative shoots, size of fl owering heads, and infl orescences. Seed
production depends heavily on the content of starch in the root crown in the period of
fl owering (correlation coeffi cient
r
= 0.63), content of sugar in nectar (
r
= 0.78), and
presence of pollinators (
r
= 0.95).
1.4 CONCLUSIONS
The complex evaluation method of vertical zoning gives an opportunity of wide phe-
notypical selection of the forms adjusted to the mountain conditions and creation of
new adaptive and productive varieties and restoration of variety of plants on meadows
and pastures.
Complex evaluation of selection samples in various conditions growing in moun-
tains and foothills in natural plant communities, in pure and mixed crops secures cre-
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