Selection evaluation of remontant raspberry varieties by bush habitus

The development of raspberry varieties with compact bushes and self-supporting stems, which require no support, is of importance for reducing the labor intensity of cultivation technology. In this connection, our research was aimed at evaluating the initial forms and their hybrid off spring in terms of bush habitus for identification of promising forms. The study included 10 varieties of remontant type, 10 selected forms, and the off spring of 12 combinations of crosses. Phenotypic evaluation of breeding material was carried out based on shoot height, internode length, bush habitus, and compactness. The Pingvin and Medvezhonok varieties, as well as selected forms No. 4-78-2, 9-155-1, 1-135-31, 44-154-2, and 1-16-11, formed low-height bushes (up to 130 cm). The remaining 65% of varieties produced plants of optimal height (132–159 cm). The internode length in the initial forms varied from 3.1 to 5.8 cm, with those having this parameter at the level of 3.1-4.0 cm being characterized by straight-growing or weakly-sprawling bushes. The group with an internode length more than 4.0 cm included seven varieties: Atlant, Komsomol’skaya Pravda, Podarok Kashinu, Zhar-Ptica, Yubilejnaya Kulikova , and selections No. 9-155-1 and 1-60-1. Among the studied varieties, Pingvin and No. 44-154-2, 1-135-31, and 4-1-30 formed compact bushes. When using parental forms with internode lengths of 3.1–4.0 cm in crosses, genotypes with shortened internodes (less than 3.0 cm) were extremely rarely bred. Among the families studied, combinations with both the absence of drooping seedlings and their significant number (20.0–48.5 %) were observed. Hybrids with a drooping bush habitus were absent in four combinations out of 12: Zhar-Ptica ×44-154-2, Atlant×Salyu t, 9-113-1× Salyut, and Atlant ×11-165-10. These families, as well as Medvezhonok×Poklon Kazakovu and 9-155-1× Atlant , were characterized by a high yield (18.9–34.6 %) of straight-grown genotypes. Among the studied hybrid progeny of remontant raspberry, six selected forms (No. 5-112-1, 5-171-2, 5-171-3, 1-97-1, 5-108-1, and 18-163-1) with a combination of upright bush habitus and other economically valuable indicators were identified.