Vernalisation of Winter Rye by Negative Temperatures and the Influence of Vernalisation upon the Lamina Length of the First and Second Leaf in Winter Rye, Spring Barley, and Winter Barley

Abstract

The lowest effective temperature observed for vernalising Petkua Winter Rye was −4.5° C., whereas −6° to −10° C. did not induce any hastening of flowering. Seedlings of 20–25 mm. length were as susceptible to −3° C. as seeds in the stage at which the radicle had just broken through the pericarp. Vernalising temperatures alternating between 7 days +1° C. and 3 days −3° C. were as effective as continuous treatment by +1° C. The lamina length of the first and second leaf is shortened by raising the vernalising temperatures from −3° C. to +3° C. and also is further shortened by prolonging the vernalisation period in winter rye and winter barley. No progressive shortening of the lamina length, however, was observed in spring barley when treated like winter barley. This suggests a direct dependence of the lamina length of the first and second leaf on the degree of vernalisation reached in the embryo.