Studies in Vernalisation of Cereals

Abstract

Vernalisation of Petkus winter rye can be reversed by high temperature. Such devernalisation was prevented or diminished by a period at the ‘neutral’ temperature (about 13° C) immediately after vernalisation, by weak light, or by restricting the growth of the seedlings by limiting the water-supply. Before vernalisation was completed, each additional week at low temperature approximately halved the percentage devernalisation possible. Prolonging the heat treatment after vernalisation led to a secondary acceleration of flowering. By subjecting intact grain and excised embryos to various alternations of low and high temperature, data were obtained from which the Q₁₀ of the devernalising process was estimated to be approximately 4, and independent of the presence of the endosperm. Exposure to high temperature before vernalisation (pre-devernalisation) reduced the effect of the cold treatment on intact grain and, to a much less extent, on excised embryos, but did not prevent completion of the process accelerating flowering if low-temperature treatment was prolonged.