Abstract:
Production of winter wheat significantly varies over the years, and in some years (2000, 2003)
its production decreased by several times, mainly
due to insufficient resistance of varieties to abiotic
and biotic environmental factors. It is necessary to
consider the opinion of academician Lytvynenko M.A. [1] that, prior to appropriate growing
conditions, variety and seeds are one of the most
available and effective means of stabilization of
production of winter wheat grains, and each variety
has its own set of yield limiting factors under
stressful weather or technological situations.
Today, a new varietal policy for optimization
of varietal peculiarities for conditions of their growing is required. A variety as a biological system is
to be considered in the aspect of implementation of
genetic potential in a specific ecological
region [2-4].
Each new variety shall combine a number of
hereditary factors that control various biological
and economic characteristics. A special place is
taken by the features that provide yield stability
under changes of environmental conditions. This
stability in time and space is determined by genetic
mechanisms of homeostasis or created at the account of its own regulatory mechanisms [5].
Many terms, such as stability, plasticity, homeostaticity, general and specific adaptive ability,
and others are used in foreign and domestic literature. There are cases when these terms are opposed
to each other or are considered synonymous, and
sometimes it seems that they are complementary. It
partially refers to the terms "stability and plasticity" [3].
When using of one or another interpretation
of the term, it is important to determine their biological essence so that their biological interpretation coincided. This understanding supposes that
the genotype is stable and its implementation is resistant. It is characterised by a response to improvement or deterioration of environmental conditions. In the broad sense, such a genotype is considered stable if its growth is insignificantly influenced
by environmental changes [6, 7].
