IDENTIFICATION AND UTILIZATION OF A DELAYED FLOWERING CHARACTER IN SOYBEANS FOR SHORT-DAY CONDITIONS

Two soybean [Glycine max (L.) Merr.] germplasm strains, 'Santa Maria' and 'PI 159925', which are classified in early Maturity Group VIII at Stoneville, Mississippi, are late-flowering under short-day conditions (daylength less than 14 h). A breeding line similar in flowering response to the cultivar Bragg, 'D72-7842' was crossed with 'Santa Maria'. Days to first flowering of F3 lines were evaluated under long-day and short-day conditions. Days to first flowering under long-day conditions could not be used to predict days to first flowering under short-day conditions. Under short-day conditions only nine of 350 lines grown equaled 'Santa Maria' in days to first flowering. In a second study, late flowering, agronomically superior lines were selected from the cross 'Tracy' × ('Hill' × 'PI 159925'). The late-flowering character can be selected readily in segregating populations grown under short-day conditions. It is anticipated that these late-flowering types will make adequate growth under short-day conditions to permit machine harvest and will not require an extremely long growing season. © 1979.