Agriculture Reference
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where
HTС
—hydrothermal coefficient;
∑Р
—precipitation amount;
∑Т
—sum of temperatures higher than +10
°
С for some period of time.
15.3 RESULTS AND DISCUSSION
The comparison of rates and intensity of wound healing to the dates of artificial notch-
ings makes it possible to classify vegetative period of the cultivars and species studied
based on their regeneration potentials into such stages as regeneration rise, relative
decrease, a second rise wave, and rather fast damping. Besides, substantial interspe-
cific and intervarietal distinctions, and in general, regeneration ability were observed,
indices of regeneration coefficient fluctuating in dependence on notching terms/dates.
Most likely seasonal variations of regeneration coefficient indices were due to the
fluctuation of weather/meteorological conditions, namely, precipitation amount and
air temperature.
In 2007-2012, average annual precipitation amount was higher in 2010 alone (by
104.1 mm). Plant moisture support in 2011 was close to average many-year indices;
in 2008 and 2009 precipitation defi cit was recorded (115.6 and 109.5 mm), whereas
in 2007 and 2012 the defi cit amounted to 217.0 and 160.1 mm, correspondingly. All
deviations/variations of average daily temperatures from average many-year air tem-
perature in the years studied, except for the year of 2011, tended to the increase of
many-year data, the temporal variations of temperature being much smaller in a rela-
tive sense than those of precipitation.
It was found out that the most favourable conditions to show regeneration potential
for pear cultivars Bere Desiatova, Umans'ka iuvileina, Kniahynia Ol'ha, and Sofi ia
were in the year of 2010. Generalized average seasonal indices of regeneration coef-
fi cient in 2010 were 5.42 urc with coeffi cient variation over 70 percent. In 2007-2009,
average regeneration potential was lower by 2.32-2.38 urc. In 2012, regeneration ex-
ceeded the indices of the years of 2007-2009, but it was lower (0.66 urc) than the
results of 2010. During the years of investigation the cultivars studied had higher
regeneration coeffi cients (over 3 urc) from May till the second decade of August in-
cluding, which coincided with the period of active plant vegetation. And the index of
over 6 urc was recorded when notchings were made from the second decade of June
till the end of the fi rst decade of July with the maximal index 6.61 urc at the beginning
of the second decade of June.
The speed at which callus developed depended on the term the notchings were
made. When notchings were made in the third decade of March in all years of investi-
gation, the index of regeneration coeffi cient of pear cultivars did not exceed two units.
The most favorable period appeared to be at the end of March in 2007 (1.96 urc),
whereas this indicator was only 1.32 urc in 2010. In the fi rst decade of April, in all
years of investigation, the indices of regeneration coeffi cient increased by 0.37-0.98
urc, and in the fi rst half of the second decade by 0.10-0.58 urc. A slight decrease of
average regeneration coeffi cient (0.48-0.51 urc) was recorded on the shoots damaged
in the third decade of April in 2007 and 2008, whereas in 2009 and 2010 in the same
period the indices of average-taxon regeneration coeffi cient continued to increase, and
they exceeded those of the previous notching term by 0.20-0.47 urc (Table 15.1).
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