A methodical approach for evaluating the variability of productivity and fruit quality in the genetic collections of strawberry (Fragaria × ananassa Duch.)

For strawberry  (Fragaria × ananassa Duch., 2n = 8x = 56), which is the leading  berry crop in the world, research  into the genotype × environment interaction is important. A complicated genomic composition, the  diversity of genetic control systems, and a strong modifying effect of growing conditions on the implementation of quantitative traits make it necessary to improve  methods for analysis of the  genotypic variability of economically  valuable  traits with the  aim of identifying genotypes that  are characterized by stability and adaptive qualities in a wide ecological  range  of growing  conditions. In 2016–2018, twenty-seven strawberry  varieties were studied in the collections of North Caucasian Federal Scientific Center of Horticulture, Viticulture and Krymsk Experiment Breeding Station, VIR Branch. Field experiments and data counts  were set and carried out according to a single scheme. The following characteristics were studied: the number of inflorescences (units per plant), the number of berries (units per plant), the average  weight  of berry and berry of the first order (g), total and marketable yield (g per plant), firmness of fruit (g), sugar content in berries on Degrees  Brix (°Bx), sugar-acid  index. The purpose of this work was the development of a methodical approach to assessing the contribution of the genotype– environment interaction to the variability of the traits of productivity and fruit quality and the determination of strawberry varieties with a stable  genotype. To this end, the mathematical models  of two- and three-factor analysis of variance and cluster  analysis using Ward’s method were employed. According to the  results  of this work, strawberry  varieties grown in different  climatic conditions show  differences  in the  structure of the  variability of the  traits of productivity and  fruit quality. For the conditions of the city of Krymsk, the influence  of the genotype of the variety was predominant, and for the  conditions of the  city of Krasnodar, in addition  to the  influence  of the  genotype of the  variety, the  environmental component in the form of the genotype–environment interaction is also significant. A statistically significant influence of the growing  zone has been  established for the traits of productivity and fruit quality, with the exception of the average weight of fruit. At the same time, differences in the mean values of the traits of varieties can be both significant and partially or completely absent. To identify varieties with promise for cultivation in the areas studied, it is recommended to use cluster analysis on the informative complex of traits with the calculation  of the Euclidean distances for varieties that were grown under  different  conditions. The magnitude of the Euclidean distance  will be the measure of the influence  of a particular environment on the  genotype of plants. The smaller the  value of the  Euclidean distance  in a variety, according to the complex of the traits studied, the more stable this variety is.

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