Genetic Divergence by Using Cluster Analysis of Estimate Heterosis in Double Crosses and Maize(Zea mays L.)


Seven pure lines of maize (Zea mays L.) (Agr-183, ZM47W, CML494, IK58, ZP505, ZP670, ZP197)were used in a half Diallel crosses program according to the second Griffing method (1956),during 2014 autumn season for obtaining ( 21) single crosses that used In the following 2015 spring season for obtaining (105) double crosses according to Rawlings and Cockerham (1962). Parents, single crosses and double crosses besides check variety (Drachma) were grown at the farm field in Tuz /Salahaddin Governorate in autumn 2015 by using Randomized Completely Block Design with three replications to study the heterosis and Genetic distance between single crosses for the flowing characters: ( days to 50% male of male and female flowering, no. ears per plant, no. of grains per ear, 300 grain weight(gm) and plant yield(gm).The genotypes( Double Crosses and commercial cross )showed significant differences at 1% level probability for all studied traits. The superiority of Double Crosses [ (Agr-183 × ZP197) × (ZM47W × ZP505) ]for the grains per ear and hybrid[(Agr-183 × ZP197) × (ZM47W × IK58) ]in the grin yield (gm), as these hybrids showed desirable hybrid vigor especially in grain yield per plant (gm) and its components .Half Diallel Crosses split studied into two main groups according to genetic relationship, genetic distance reached the lowest value (526.304) between (ZM47W × IK58) and (IK58 × ZP670) hybrids, while the highest value( 31053.542) was between (Agr-183 × ZM47W) and (ZM47W × CML494) hybrids. The genetic distance based on phenotypic indicators that are affected by the environment do not give an accurate measure of the genetic distance among genotypes especially double crosses composed of four parental lines .