Variation in seasonal timing of flower bud initiation in black currant (Ribes nigrum L.) cultivars of contrasting geographic origin

Abstract

SummarySeasonal time-courses of flower bud initiation and differentiation were monitored during two growing seasons (2011 and 2012) in 19 black currant cultivars of distant geographic origin, grown in the field at a South Norwegian locality (60°40’N, 10°52’E; 250 m asl). For comparison, the time-courses of shoot elongation growth in 15 of the same cultivars were also monitored during the 2012 growing season. The results revealed widely different seasonal timings of growth cessation and floral initiation in cultivars of different latitudinal origin. High latitude cultivars originating from crosses and selections of local, wild black currant populations from the Kola peninsula and Swedish Lapland were particularly early and had ceased growing and had initiated floral primordia by mid-June. This was approx. 5 – 6 weeks earlier than any of the other cultivars from lower latitudes. However, these also varied in their earliness of growth cessation and flower initiation in relation to their latitudinal origin. Many cultivars bred and selected in Southern Scandinavia, Scotland, and Poland did not cease growing and initiate floral primordia until late August, 9 weeks after the early, high-latitude cultivars. Overall, the 19 cultivars constituted a typical latitudinal cline in their photoperiodically controlled timing of growth and flowering responses. The high-latitude Russian cultivars ‘Imandra’ and ‘Murmanschanka’ represent valuable additions to the limited diversity of the available black currant gene-pool, and may be of particular use for breeding cultivars adapted to the sub-Arctic environment.