Glume Pubescence and Its Influence on Spikelet Temperature of Wheat under Freezing Conditions

Abstract

Newly produced synthetic hexaploid wheats possessing pubescent glumes were observed to suffer less frost damage than non-pubescent plants after experiencing severe frosting in the field during April 1997. In order to test the potential advantage conferred by glume pubescence, pubescent and non-pubescent plants were selected from a collection of synthetic hexaploid wheats, as well as from F4 derived F7 lines selected from crosses between pubescent synthetic parents and elite spring bread wheat lines.

Comparisons were carried out in a controlled temperature chamber. Flowering plants grown in pots were subjected during a 6-h period to a gradual temperature change ranging from 20°C to -4°C. Floret temperature was measured using micro-thermocouples and temperature averaged at 120 sec intervals was recorded by a data logger. Results indicated that the temperature of pubescent florets was higher than that of their non-pubescent equivalents. Significant temperature differences at freezing varied between +0.25°C and +0.47°C among the tested genotypes. The appearance of an exotherm, which presumably coincided with the point in time at which water changed from liquid to solid phase was delayed by as much as 3.27 min when pubescence was present. Pubescent plants also produced a higher number of grains per spikelet compared to non-pubescent ones. These observations suggest that glume pubescence is a factor that may influence the damaging effects of frost at or following anthesis.