Effects of Four Temperature Regimens on the Gibberellin Content of Winter Wheat cv. Kharkov

Abstract

Abstract Kharkov 22 M.C. winter wheat was grown continuously from seed under four temperature regimens; 2°C; 2°C then transferred to 20°C; 6°C, and 20°C. Plants were harvested at the 4‐leaf stage (except the 2°C plants which were harvested at the 3‐leaf stage) and the levels of endogenous gibberellins (GAs) were measured and their cold hardiness determined. The GA content of 20°C and the 6°C seedlings were about equal and greater (by 4‐ to 30‐fold) than the GA content of 2°C seedlings that had been transferred to 20°C ( i.e. vernalized). The GA content of the 2°C seedlings was least of all, being 28‐ to 320‐fold less than the 20°C seedlings. At harvest the leaves of the 20°C seedlings were somewhat larger than those of the seedlings grown at 2°C and transferred to 20°C. The leaves of the 6°C seedlings were very much smaller and the leaves of the 2°C seedlings were smallest of all. It is concluded that while GAs may play a role in controlling leaf size and level of cold hardiness of wheat, they are not the most important factor.