Genetic characterization of flowering of diverse cultivars of pea

Genetically controlled responses to photoperiod and temperature combine to determine wide variations in flowering time of pea (Pisum sativum L.) and aid the breeding of crops adapted to target environments. Our objective was to model the flowering responses of eight diverse cultivars of pea to photoperiod and temperature in order to estimate their probable flowering genotype for the flowering time genes Lf,SR, E, and Hr. Plants were grown in pots in 11 contrasting semicontrolled and natural environments. Durations from sowing to flowering and nodes of first initiated powers were recorded. Photothermal flowering responses of each cultivar were quantified using a two-plane photothermal model that linearly relates the rate of progress from sowing to flowering with the mean preflowering values of temperature and/or photoperiod. Flowering genotypes were estimated based on the similarities of these response planes to those of reference lines of known flowering genotypes, The estimated flowering genotypes of the eight cultivars were NZ 6753, If sn; Bolero, Lf Sn hr; Conway, Lf(d) SR hr; Fjord, Lf(d) SR Hr; Botanica-INIA, Lf Sn hr; Amarilla-INIA, Lf(d) SR hr; Lebu Loma 13, if e SR hr; and Catrico SS, Lf(d) Sn Hr,The flowering responses described by the linear photothermal model provided quantitative information for estimating the flowering genotype complementary to that of the usual semiquantitative approach based on the node of flower initiation. We concluded that the linear photothermal model provides a sound basis for describing the flowering responses of pea cultivars in order to estimate their probable flowering genotype.