Agronomic and biological evaluation of primocane raspberry varieties

Abstract . The paper presents a preliminary study on selected varieties of primocane raspberry in Bryansk oblast. The aim of the research was to identify new genetic sources for breeding and to select candidates for new cultivars. The study was conducted from 2022 to 2024 following standard methods of cultivar research and involved 18 select ed varieties developed through in-house breeding. For the assessment of phenorhythms and productivity components, diff erent standard cultivars were used based on ripening time: Medvezhonok for early forms, Poklon Kazakovu for mid-season forms, and Atlant for late forms. The cultivar Atlant was also used as the standard for fruit quality pa rameters. The selected forms were categorized into three groups based on ripening time. The early group included selections No. 5-171-1, 5-171-2, 44-154-2, 3-120-12, 4-78-2, and 10-165-11, with the onset of ripening occurring between July 21 and August 2. The mid-season group consisted of No. 1-127-1, 1-66-1, 1-60-12, 3-26-2, 9-172-11, 17-164-11, and 1-188-2, which began ripening between August 6 and August 13. The late-ripening forms No. 5-134-1, 13-162-1, 3-175-1, 7-175-1, and 6-124-21 started fruiting between August 21 and August 28. New genetic sources were identifi ed for further breeding aimed at better productivity. The following selections demonstrated large fruit size, with an average berry weight of 5.5–6.0 g: No. 5-171-1, 1-188-2, 3-26-2, 1-127-1, 4-78-2, 1-60-12, and 7-125-1. Stems with a high number of reproductive organs (176–221 buds, fl owers, and fruits per stem) were observed in se lections No. 17-164-11, 13-162-1, and 1-188-2. New sources for improving fruit quality and technological properties were identifi ed: selections with a dessert-like taste and aroma included No. 9-172-11 and No. 5-134-1; those with increased soluble solids content (11.7 %) included No. 5-134-1 and No. 3-26-2; and selections with enhanced fruit f i rmness (8.8-10.1 N) included No. 1-66-1, 1-60-12, 1-188-2, 3-125-1, 6-124-21, 7-125-1, and 44-154-2. Several selected varieties (No. 3-120-12, 4-78-2, 17-164-11, 1-188-2, and 7-125-1) exhibited a combination of multiple ag ronomically desirable traits at a high level. Selection No. 1-60-12, characterized by a promising biological potential for productivity and fruit quality, merits consideration as a candidate for a new cultivar.