Breeding primocane raspberries (Rubus idaeus L.) for mediterranean climates: Improved yield and fruit quality

• Shorter breeding lines L12 and L92 produced the highest total yield. • L12 and L92 showed a higher average fruit weight than Amira. • L12 and L92 displayed a higher sugar/acid ratio. • L92 accumulated comparable levels of ionones to Amira. • L12 and L92 showed increased raspberry ketone than Amira. Global demand for raspberries is rising, driven by consumer interest in their flavor and health benefits, creating a need for new cultivars adapted to warmer regions such as the Mediterranean. This study analysed fruit yield, size, taste, aroma, and health-promoting compounds of five newly developed primocane raspberry breeding lines (L12, L25, L71, L92, and L216) and compared them with the commercial cultivar (Amira) under the Mediterranean climate. The earliest-yielding breeding lines were shorter in height and produced a higher yield than the 'Amira' cultivar, partly due to larger fruit size. On a fresh weight (FW) basis, the contents of fructose (16.7 to 23.0 g kg -1 FW), glucose (16.9 to 24.3 g kg -1 FW), and sucrose (2.50- 4.90 g kg -1 FW) varied across the breeding lines. Citric acid (12.0 to 19.3 g kg -1 FW) was the predominant organic acid (about 70 % of the total acids). Total phenolic content (TPC) ranged from 4.72 to 7.05 g kg -1 FW. The total volatile organic compounds (VOCs) concentration ranged from 1392 to 2562 µg kg -1 FW with aromatic norisoprenoids (β-damascenone, α-ionone, β-ionone, and dihydro-β-ionone) and raspberry ketone showing odor active value (OAV) > 1, highlighting their pivotal role in defining raspberry aroma. Our results show that breeding lines L12 and L92 were superior in several key aspects, including fruit size, yield, flavor, and health-promoting compounds. These findings highlight that breeding for primocane cultivars with early fruiting and large fruit size is a promising strategy for aromatic, tastier raspberry cultivation in warm climates.