Genetic variation in horticulturally important traits of fifteen wild lingonberry Vaccinium vitis-idaea L. populations

Plant breeding of lingonberry (Vaccinium vitis-idaea L.) is still in its infancy. In order to optimize sampling strategy to broaden the genetic base and to improve horticulturally important traits, we need more information about the genetic structure of wild populations. In a field study, seeds were collected from thirteen widely spaced lingonberry populations in Sweden, from one in Estonia and from one in Japan. The resulting seedlings were subsequently transferred into a field with a randomized design and were investigated regarding horticulturally important traits (growth, flowering, phenology and cropping performance). Common for all traits was that the amount of variation (mean for 17 traits: 21.8% +/- 11.2) was smaller among populations than within populations. In spite of this low variation, the study revealed significant genetic variation (p <0.05) among populations in nearly all traits investigated. Significant correlations were found between several traits: between plant width and plant height (r=0.516, p <0.001), between plant height and total fruit yield (r=0.253, p <0.001), between number of rhizome-derived daughter plants and total fruit yield (r=-0.189, p <0.001) and between the beginning of spring flowering and the duration of repeat flowering (r=-0.354, p <0.001). Many traits were associated with the latitude of the sample location, e.g. duration of flowering (r=-0.620, p <0.05) and total fruit yield (r=-0.580, p <0.05). Populations collected from southern latitudes (56 degrees -60 degreesN) in general showed better values than the northern populations for horticulturally important traits. The Japanese population, which belongs to the subspecies minus, differed in many traits from all the other populations which belong to the subspecies vitis-idaea.