Productivity and adaptability of white clover lines in the forest-steppe of the Middle Volga region
The aim of this research was to evaluate promising genotypes of white clover with regard to its productivity and resistance in the forest-steppe of the Middle Volga region. The experiment took place on the trial field of the Penza branch of the Federal Research Center of Fibre Crops in 2016-2019. A competitive variety trial started in 2015. Environmental conditions varied among years of study. Optimal conditions were in 2016 and 2017, hydrothermal coefficient amounted to 1.1 and 1.2, respectively. Weather of 2018 and 2019 was dry, hydrothermal coefficient reached 0.5 and 0.4, respectively. Dry matter (DM) productivity varied within 2.43-2.76 t ha<sup>-1</sup>. Pl-90-5 line performed the best producing 2.76 t DM ha<sup>-1</sup>. Yield variation was high among all the genotypes. Plants showed high adaptability and plasticity: bi varied within 0.95-1.15. Such lines as Pl-90-2, Pl-90-3, Pl-90-4 and Pl-90-5 had the best adaptability and plasticity (bi=0.95-1.10, σ<sub>d</sub><sup>2</sup>=0.0-0.07). Pl-90-5 had the highest stability of 116.7%. The highest stability index of 0.06 was determined for four genotypes, including standard variety. Four genotypes had adaptability coefficient of 1.0-1.07, Pl-90-5 showed the highest adaptability. Pl-90-2 and Pl-90-3 had the highest stress-resistance. The highest plasticity between genotype and environment was observed for Pl-90-4 and Pl-90-5 (2.74-2.77).