Insensitivity to Gibberellin in Dwarf Wheats

The responses to GA were observed in three genetically distinct dwarf wheats and compared to that of tall controls. Height, internode number and length, dry weight, and flowering time were greatly affected by GA in the tall varieties, and hardly at all in the dwarfs. However, the dwarfs did respond by producing more tillers, unlike the tall varieties which produced less lateral growth with GA treatment. The aleurone layers of the seeds of the tall varieties and Norin 10-Brevor 14 produced α-amlyase in response to GA, whereas in the other dwarfs this response was greatly diminished. The possible modes of action of the hormone in wheat is discussed in the light of these results.