Problems and productivity of winter wheat varieties selection with increased environmental stability

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].