Photoperiod Sensitivity of Rhizoma Peanut Germplasm

Abstract

Short days are thought to alter dry matter (DM) partitioning in rhizoma peanut (Arachis glabrata Benth.). Under controlled environmental conditions, six lines of rhizoma peanut germplasm (cultivars Florigraze and Arbrook; Florida lines Ecoturf, Arbrook Select, and Arblick; and PI 262826) were exposed to natural and extended photoperiod regimes (15 or 18 h). The study started 21 Sept. 2000 and ran until the following May; aboveground DM was harvested five times. The following year the same lines were transplanted into the field, where they received either natural light or 15 h extended photoperiod conditions between 20 Sept. 2001 and 19 Apr. 2002 and again during the winter of 2002–2003. In the field, cover and DM was determined on approximately 9 wk intervals. In the controlled environment study, both extended photoperiod treatments increased DM yield, but the 18 h treatment was most consistent across selections and dates. The February response was greatest when there was greater than fivefold increase across selections for the 18 h treatment above natural photoperiod (2.80 vs. 0.52 g/pot, respectively). In the field, percent cover was enhanced by extended photoperiod for all selections except Ecoturf by the second sampling date after the lights were turned on (avg. 90 vs. 38% cover, respectively, for extended and natural photoperiod). Cover differences persisted until June 2002. Dry matter yield also was increased by treatment during the fall of both years. These studies suggest that selection for late and early season DM production in rhizoma peanut will select for photoperiod insensitivity.