Genotype Differences in Photoperiodic Sensitivity and Vernalization Response in Wheat

The regression of final leaf number on leaf number at transfer from an 8 h to an 18 h photoperiod was used to compare the photoperiodic response of eight locally-adapted lines of wheat. Comparisons of such regressions in the vernalized and univernalized conditions enabled detection of the presence or absence of a significant cultivar vernalization response and comparisons of differing responses between cultivars. Prior vernalization generally did not significantly alter the ‘rate’ of photoperiodic response, as the slope of the LNT/FLN regression, indicating a certain physiological independence of vernalization and photoperiodic responses in wheat. Differences, both in photoperiodic and vernalization response of the eight wheats studied have been discussed in terms of adaptability and breeding for maturity alteration in wheat. Evidence has been produced for the possible existence of a third factor influencing developmental processes associated with flowering in wheat.