Photoperiod Influence on Development in Sunflower Genotypes1

Abstract

AbstractSynchronization of anthesis of male and female inbred sunflower (Helianthus annuus L.) lines to be crossed in either breeding nurseries or seed production fields is important. Research was conducted to determine the influence of photoperiod on phenological development in a diverse group of sunflower genotypes. An understanding of this response would allow the development of a model to predict sunflower anthesis. Sixteen sunflower genotypes, including hybrid and inbred lines, were classified for photoperiod response in greenhouse plantings carried out over a 2‐yr period at Fargo, ND (latitude 46°54′N, elevation 183 m). Plantings were made so that emergence occurred each time natural photoperiod changed by about 1 h. Although some genotypes displayed long‐day, short‐day, or insensitive photoperiodic reactions for the period from emergence to floral bud development, many of the genotypes appeared to be ambiphotoperiodic, with 11 through 13 h at emergence being the photoperiods delaying time to flower bud development. This delay could be of consequence to breeding programs in those latitudes where planting dates may result in emergence and early growth of the sunflower coinciding with these intermediate photoperiods.