INDUCTION OF SEED SET IN DWARF-SPRING AND WINTER WHEAT

Abstract

Studies were made of the effect of gibberellin (GA) application to dwarf plants of spring wheat (Triticum aestivum L.) which resulted from crossing monosomic and disomic Redman with Kenya Farmer. GA at 10 and 100 p.p.m. induced the formation of 53 seeds on 12 plants sprayed 46 days after planting. Fewer seeds were produced on a larger number of plants sprayed at a later stage. The application of IAA, NAA and TIBA to dwarfs at 5 p.p.m. was ineffective in increasing step length or inducing heading. Cold-shock treatment of seeds appeared to induce heading in one experiment and not in another. GA did not affect the course of meiosis but it did cause deformities in plants grown from treated seed. Deformities included branching of the main stem, development of crown roots from two or three nodes per stem, and rapid growth of a "needle-like" internode. Application of fertilizer overcame yellowing but not the spindly growth which occurred in GA-treated plants. Two winter wheat varieties were given GA and cold treatment both of which induced heading in one variety and not in the other. GA induced extensive growth of leaves and stems in both winter wheats under low intensity light and high temperature whereas under opposite conditions it caused retarded growth and delayed maturity.