Abstract

Environmental plasticity is an important indicator of new varieties. This assessment should be carried out prior to their implementation in production in order to more accurately determine the compliance of the variety and its cultivation conditions. At the Institute of Agrobiotechnology of the Federal Research Center of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (Russia, Komi Republic, Syktyvkar) two new potato varieties (Zyryanets and Vychegodsky) were developed. The characteristics of these varieties meet all the requirements that were set for them viz. the formation of grocery-ware tubers during three months of summer vegetation, with an average of not more than 12 tubers per plant, high field plant resistance to various diseases of both the potato tops and the tubers. The plasticity of these varieties was evaluated based on three years of field resistance. The potatoes were planted on experimental sites of the Institute. On those fields, six-field crop rotation was maintained to ensure high soil fertility without the use of either mineral or organic fertilizers. The sod-podzolic soil had 3.4% of humus. The content of main nutrients was as follows: Ntot. - 90 mg/kg, P2O5 - 597.5 mg/kg and K2O - 103.7 mg/kg of soil. The potatoes were planted on the 70 × 30 cm spacing plan to a depth of 8-10 cm. The area of the test plot was 52.5 m2 (250 tubers) in quadruple repetition. The studies were conducted from 2017 to 2019. A comprehensive assessment of weather factors (precipitation and temperature) in 2017 to 2019 showed their influence on the studied potato varieties was conducted by calculating the environment index. This indicator allowed the authors to obtain the βi linear regression coefficient, which in this case shows the dependence of the yield of the varieties on the conditions in which they were grown. Two varieties were selected as controls: Nevsky (middle-early) and Udacha (early). The Nevsky variety bears a linear dependence of its yield changes on environmental conditions (Bi = 1.0). On the contrary, the Udacha variety was non-plastic, and its yield varied slightly as environmental conditions changes (βi = 0.5). It was found that the Zyryanets variety bears high responsiveness to environmental conditions (βi = 1.7). In favourable years, it was capable of producing very high yields, although the yield drops sharply during unfavourable years. The Vychegodsky variety was more stable (βi = 1.2) as far as its responsiveness to environmental conditions. Therefore, it suits agro-climatic conditions of the Komi Republic better. In terms of its characteristics, this variety is similar to the Nevsky one, which has long been recommended for cultivation in the Komi Republic but has a higher yield by 1.7 t/ha. These studies have shown that in order to strengthen the country’s food security and further promote potato varieties to northern territories of the European part of Russia, especially in polar latitudes, obtaining high yield and disease resistance indicators is not enough - one also needs to take environmental stability into account. This will allow cultivating varieties with predictable yield under risky farming conditions.