Spring phenological adaptation of improved blue honeysuckle (Lonicera caerulea L.) germplasm to a temperate climate

Abstract

The blue honeysuckle (Lonicera caerulea L.) has outstanding features as a novel fruit crop, including extreme winter hardiness, resistance of flowers to severe frosts and early season phenology. Its northern climatic adaptation also limits its range of production. Therefore, crop enhancement requires development of germplasm with adaptation to temperate climatic regions suited to large-scale horticulture. In a cold continental climate, the University of Saskatchewan fruit breeding program utilizes a wide-cross breeding strategy to produce improved germplasm groups from foundation groups from Russia, Japan and the Kuril Islands. A key objective is to evaluate temperate climate adaptation in these improved groups compared to their parental foundation genotypes. In a temperate climate in the Fraser Valley, British Columbia, Canada, evaluation of spring phenology in 2012 and 2013 compared blue honeysuckle to blueberry, raspberry and strawberry. By determining the range of variation within improved groups and the general mode of gene action controlling phenological traits, the current study characterized methods to enhance temperate climate adaptation through breeding. The improved groups generated from wide crosses exhibited hybrid vigour for numerous traits, presenting opportunities for broadening the crop’s range of production. Selection for enhanced adaptation will be possible due to prevalence of intermediate types between the phenological extremes seen in the Russian and Kuril groups, moderation of these extremes by the Japanese group’s intermediate phenology through dominant and overdominant gene action and high broad-sense heritability. Long-term genetic gains are most feasible for combinations of Japanese and Kuril groups, especially in bloom phenology.