Стр. 12 - yurchak-ev-k

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12
Third period
(1971‒2010) characterizes L.D. Yurchak as an independent
researcher. This stage covers a large period of time, so it is divided into five stages
to help detailing the scientist’s research work.
At first stage
(1971‒1975)
,
after defense of the candidate’s thesis, the
scientist continued profound microbiological research of green-manure properties
of lupin: she studied allelopathy of active compounds of aqueous extracts and
volatile substances formed in disintegration of lupin; she also examined the effects
of active metabolites of microorganisms on lupin digestion etc.
Second stage
(1975‒1980) covered L.D. Yurchak’s research works in
chemical interaction between agricultural field and forage crops. She actively
studied reduction of soil fatigue effects on the above-mentioned crops, reasonable
fertilizer use, and study of plant discharge role in soil toxicity.
Third stage
(1980‒1990) was associated with L.D. Yurchak’s research
studies of various phytocenosis types. She leaded the group of like-minded
scientists, and together they made great scientific achievements with specific focus
on study of allelopathic properties of alien aromatic crops. She conducted research
works to identify the most allelopathically active medicinal plants, and to select
relevant plant tests.
Fourth stage
(1990‒2002) of L.D. Yurchak’s professional activities covered
experimental studies of allelopathic mechanisms underlying aromatic plant
discharges during ontogenesis, determination of soil fatigue causes etc. She
prepared and published “Guidelines on Cultivation and Harvesting of Clary Sage
in the Forest Steppe Areas of the USSR” (1990) and the monograph “Clary Sage
Crop in the Forest Steppe of Ukraine” (1997).
Fifth stage
(2002‒2010), after defense of thesis for a Doctor Degree in
agricultural science “Ecologic Bases of Allelopathic Interaction and Aftereffects
of Aromatic Plants in Agrophytocenoses” (2002), L.D. Yurchak deeply studied
allelopathic properties of aromatic substances. She published her personal
monograph “Allelopathy in Agrobiogeocenoses of Aromatic Plants” (2005),
where she described the latest achievements in allelopathy in Ukraine. Scientific