DIFFERENTIAL RESPONSE OF CERTAIN BARLEY AND WHEAT VARIETIES TO HARDENING AND FREEZING DURING SPROUTING

Abstract

A number of barley and wheat varieties from different geographical areas were tested for cold hardiness in the sprouted seed stage. The young plants were subjected to a hardening process for varying periods and at different temperatures. Under appropriate conditions of hardening and freezing nearly all of the varieties of winter wheat and winter barley showed a similar hardening pattern, that is, a relatively high degree of hardiness and ability to harden in young stages of germination (up to 1 week of growth at 1.5 °C), a minimum hardiness at 2 or 3 weeks of hardening at 1.5 °C, and a second maximum of hardiness at about 6 weeks of hardening at 1.5 °C. Spring varieties and some West European winter wheats with low winter hardiness did not show the second maximum of hardiness after 6 weeks at 1.5 °C. In general, additional hardening for 1 week at −4 °C produced a striking increase in hardiness. For barley this increase was produced at all stages of development whereas for wheat there was a large increase only after 1 to 5 weeks of prehardening at 1.5 °C. Hardening at −4° C for longer than 1 week did not produce additional hardiness. Possibilities of testing for cold hardiness at different growth stages of sprouted seeds under various conditions of hardening are discussed.