The Transgressive Inheritance of Reaction to Flag Smut, Earliness of Heading, Partial Sterility, and Stiffness of Glumes in a Varietal Cross of Wheat1

Abstract

A cross was made between a Chinese variety and Nebawa introduced from Australia. Both varieties are common wheat, Triticum vulgare. A genetical study was made in the F1, F2, F3, and F4 of this cross. The two parents were free from flag smut and were medium late, easy in thrashing, and fully fertile. The F2, F3, and F4 of the cross gave a small percentage of susceptible plants. The genes for flag smut reaction appear to be multiple in nature. A part of the population in F2 headed earlier but none later than either parent. In F3 several progenies headed significantly earlier than the early parent 4592 and a few plants F3 headed slightly later than the late parent, Nebawa. The genes responsible for earliness of heading seem to be multiple in nature, and the early genes are partially dominant over the late genes. Some plants in F2 and F3 had stiff glumes and some were partially sterile. Transgressive inheritance of the first three pairs of characters was obtained. This is a good example of a geographically distant cross giving transgressive inheritance. The authors have obtained a similar case of transgressive inheritance in earliness from a cross between Prelude, an American variety, and Nanking 2905, a Chinese improved strain by head selection from a native variety. L.Y. Shen obtained transgressive inheritance of earliness in her crosses between Chinese and foreign varieties. Accumulation of such cases may reveal the origin of hereditary variations. Crosses of polyploid varieties may give better chances for obtaining transgressive inheritance than crosses between diploids. The segregation of partial sterile plants resulted from chromosomal aberration.