ESTIMATION OF GENE EFFECT TYPES FOR EARLINESS, YIELD AND ITS ATTRIBUTES IN SIX BREAD WHEAT POPULATION

Six populations of three wheat crosses were grown during three consecutive seasons, at Fac. of Agric., Zagazig Univ., Egypt to estimate the adequacy of genetic model of gene action for the evaluated characters. Scaling tests data indicated that non-allelic interaction controlled most of the studies traits in all crosses, except days to heading in t 3rd one. The genetic model recorded that all genetic types were significant for plant height in the 3rd cross. Dominance (h) gene effect was negative and significant for days to heading and plant height in 2nd cross, whereas it was positive and significant for spikes/plant in 2nd cross and grains/spike, weight of 1000 grain and grain yield/plant in all crosses. Heritability was high (>50%) for days to heading in 1st and 2nd crosses, plant height in 1st cross and spikes/plant number, weight of 1000 grain and grain yield /plant in the 2nd one. Dominance ratio was less than unity in 1st and 2nd crosses for days to heading, 3rd cross for spikes/plant and the 2nd cross for weight of 1000 grain. Days to heading recorded a moderate genetic advance in the 1st and 2nd crosses, whereas a low values of this parameter were recorded in the 2nd and 3rd crosses for plant height and in all crosses for spikes/plant, grains/spike, weight of 1000 grain and grain yield/plant.