The inheritance of grain hardness in wheat as measured by the particle size index

Abstract

The difference in particle size index between a hard wheat (Falcon) and a soft wheat (Heron) is shown to be due to a single major gene. Tests of F2 populations of seven other crosses between hard and soft wheats indicate that this is not uncommon. The existence of minor genes which modify the action of the major gene in determining the hardness or softness of wheat grain is also demonstrated. In at least one case (Spica) a different level of hardness appears to be due to a different major gene from that found in Falcon and not to modifying genes. The conversion of a hard wheat to a soft wheat or vice versa can be achieved by backcrossing. The grain hardness of the new wheat will be influenced both by the hardness of the donor parent and by the degree to which modifying genes are carried over. This demonstration of the simple inheritance of grain hardness as measured by particle size index is of significance to wheat improvement programmes.