Difference in Vernalization Effect in Wheat under Various Temperatures

Abstract

Wheat seeds or wheat plants were kept under constant conditions of various temperatures permitting their growth in order to study the difference in vernalization effect resulting from the variation of temperature of treatment. (1) Sprouted seeds of wheat varieties such as Akabōzu, Norin No. 4, Norin No. 27, and Akakawaaka, each of which requires different intensity of low temperature for heading, were treated by various temperatures ranging from 1°C to 18°C for different durations. In varieties Akabōzu, Norin No. 4, and Norin No. 27, the plants treated at 8° C or 11°C emerged their final leaves early and those treated at 1°C emerged late. In variety Akakawaaka, 4°C and 8°C were the most favourable temperature. It is suggested from this experiment that the vernalization response proceeds more slowly at 1°C than at 4°, 8°, or 11°C. (2) Variety Norin No. 27 of different age of plant was treated at 0°, 5°, and 10°C for 30 days. The vernalization effect decreased with the increase of age of plant. The plants aged 90 days had no vernalization effect. In each plant age, the plants treated at 0°C showed less vernalization effect than those treated at 5°C or 10°C. (3) Variety Norin No. 27 was grown under the temperature of 0°, 4°, 8°, or 12°C respectively for 36 days after sowing. On the other hand, treatment at 0°, 4°, 8°, or 12°C for 12 days was respectively intercalated at the time of 0, 12, 24, or 36 days after sowing. When the plants were grown under 0°C, there was a little difference in the time of final leaf emergence inspite of the variation in temperature of intercalating treatment. When the plants were grown under 4°C or 8°C, the final leaf emergence were markedly hastened by the treatment at 12°C following the growth period of 36 days. When the plants were grown under 12°C, the plants, in which the treatment of higher temperature was intercalated at early or late stage of growth period, emerged their final leaves earlier, but when the treatment was intercalated at middle stage of growth period, there was little difference in the time of final leaf emergence in spite of the variation in temperature of treatment. The author wishes to express his sincere thanks to Prof. Shizuo Yoshida, Univ. of Osaka Prefecture, for his kind guidance through the experiments. Thanks are also due to Prof. Yo-shizi Togari, Tokyo University, for helpful suggestions and criticisms. © 1966, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.