Birdsfoot Trefoil Pod and Seed Development Affected by Temperature

Genotype × environment interactions determine where birdsfoot trefoil (Lotus corniculatus L.) seed is produced. Temperature is an important environmental variable during seed production. The objectives of this research were to determine the effects of temperature regimes (two alternating and two constant) on development of pods and seeds in birdsfoot trefoil and to examine the effect of seed position in the pod and number of pods per umbel on seed size. Ramets of three genotypes from each of three cultivars were grown in controlled environment chambers under a ;16 h photoperiod at four temperature regimes: (i) 27/13 °C day/night; (ii) constant 20 °C; (iii) constant 26 °C; and (iv) 31/21 °C day/night. Temperature regimes (i) and (iv) simulated the temperatures during pollination and seed development in Roseau, MN, and Columbia, MO, respectively. Seed mass and number of pods per umbel were not correlated. Seed mass was linearly related to location within the pod, with the heavier seed being at the distal end. Stem length, peduncle length, umbels per plant, vegetative dry mass, pod length, and seed mass were significantly greater in regime (i) compared to regime (iv). Peduncle length, pod length, and seeds per pod were significantly greater in regime (i) compared to regime (iii). Stem length, umbels per plant, vegetative dry mass, pod length, number of seeds per pod, and seed mass were greater in regime (i) compared to regime (ii). All genotypes performed better and produced larger seed at the cooler regime (i) than at regime (iv). No temperature X genotype interactions were detected. These data support the reports that birdsfoot trefoil seed production usually is most effective in areas having cool summer temperatures. Joint contribution from the Minnesota Agric. Exp. Stn. and the USDA-ARS. Paper no. 15 794 scientific journal series, Minnesota Agric. Exp. Stn.