Flowering genes and the photothermal flowering responses of pea (Pisum sativum): a re-analysis

Abstract

Attempts to quantify the effects of the flowering genes Lf, Sn and Hr in Pisum sativum L. on durations from sowing to flowering (f) have been hindered by the often strongly interactive effects of temperature and photoperiod. The original data of Berry and Aitken (Australian Journal of Plant Physiology 6, 573-587, 1979) for six cultivars have been re-analysed as rates of progress from sowing to flowering (1/f) and expressed as functions of mean pre-flowering values of temperature (T) and photoperiod (P). The photothermal responses of rates of progress from sowing to flowering were clearly divided into two planes, with the boundary defined by the critical photoperiod (Pc). Variations in the response to temperature when P<P-c were associated with differences in alleles at the Lf locus, whereas variations when P>P-c were associated with differences at the Hr locus in the presence of Sn. Allele sn determined a single-plane response to temperature alone (i.e. a day-neutral response). The base temperature for 1/f when P>P-c was 1 degrees C for all six cultivars. The linear photothermal model used provided a robust quantitative basis for analysing the effect of flowering genes in pea.