New apple-tree (Malus domestica Mill.) varieties as sourses of breeding valuable traits

Abstract

Aim. To identify sources of several valuable economic and biological traits among new Ukrainian and foreign cultivars. Results and Discussion. The weather in the spring of 2019 and 2020 contributed to the epiphytotic development of scab, which allowed for assessment of susceptibility of new cultivars to this disease and for identification of sources of high resistance to it. There were no pathogen signs in immune cvs. Harant, Goldrush, Topaz, and William's Pride, which are carriers of the scab resistance oligogen (Vf). No cultivars that would be consistently highly-resistant to this disease in the field have been found. The creation of cultivars with a columnar crown remains a promising trend in breeding. Cv. Ruslan is a columnarity source. As to fruit yield, the leaders were Elise, Geneva Early, Goldrush, Honeycrisp, Pilot, and Topaz. Cvs. Harant, Ruslan, Elise, William's Pride gave stable fruit yields. Cvs. Kakhovske, Alionushkino, Julia, Honeycrisp, and Topaz give yields every year. Cvs. Harant, Malakhit and Rubin are sources of large fruits. Cv. Harant is noticeable for stable expression of this trait, which makes it a reference of large fruits. Mid-sized apples are considered the most optimal for selling. The sources of this trait are cvs. Ruslan, Elise, Honeycrisp, Szampion Arno, and Topaz. Most of the studied cultivars have round or flat-round fruits. Kakhovske apples are distinguished by their unordinary oval (sinapoid) shape. Sources of several features that determine highly-attractive appearance of their fruits have been distinguished. These are cvs. Harant, Malakhit, Ruslan, Elise, Geneva Early, Honeycrisp, Rubin, and William's Pride. Apples of cvs. Kakhovske, Elise, Honeycrisp, Rubin, and William's Pride are characterized by excellent palatability. Cultivars that are sources of several valuable economic and biological traits have been selected. Conclusions. Modern apple cultivars are starting material for creating new cultivars that will meet the future requirements. Cvs. Harant, Ruslan, Elise, Honeycrisp, Topaz, and William's Pride are sources of the maximum number of selectively valuable traits. By crossing them with cvs. Kakhovske, Malakhit, Alionushkino, Geneva Early, Goldrush, Julia, Pilot, and Rubin, it is possible to obtain genotypes with various ripening periods, which would combine immunity to scab, compact crown, high and stable yield, and high quality fruits.