Inheritance of long juvenile period under short day conditions for the BR80-6778 soybean (Glycine max (L.) Merrill) line

The long juvenile period characteristic (LJP), which delays flowering under short day conditions, has been identified in soybean cultivars (Glycine ma x L. Merrill). This characteristic may be especially important as it increa ses the range of adaptation of soybean in low latitudes and gives greater f lexibility for sowing periods within the same latitude. The inheritance of the long juvenile period was studied in the BR80-6778 soybean line to provi de knowledge to support the development of cultivars adapted to short day c onditions. Cultivars with classic flowering, Parana, Bossier, Bragg and Dav is, which flower early under short day conditions, were also used as parent s in single crosses. They were crossed among themselves and with the genoty pes with LJP, BR80-6778 and MG/BR 22 (Garimpo). The study was carried out u nder short day conditions (early sowings) in greenhouses and in the field a t Embrapa National Soybean Research Center, Londrina, PR. Flowering was ass essed daily. The results indicated that the BR89-6778 line shares a pair of alleles with the Parana cultivar, and when associated with the cc allele r etards flowering under short day conditions. The following genotype constit utions were attributed to the cultivars: Parana (aaBBCC), Bossier (AabbCC), and BR80-6778 (aaBBcc). The combination of the genes aabb and aabbcc has a pronounced effect on the manifestation of the trait.