GENETIC ANALYSIS AND ESTIMATION OF SOME GENETIC PARAMETERS OF MAIZE TOP CROSSES

Abstract

A field experiment was conducted at Al-Madain district, during spring and fall seasons of 2007. Hybridization program( line ×tester ) experiment was conducted with six inbred lines of maize ; Agr 183 , Wc 163, PAN 466 , De Kalb 243 , X q880 and YUZPT 75 ( maternal), with two testers, lba 5012 and Tallar, (perental), during spring season. In fall season, field yield trail was conducted, sowing these genotypes (six pure lines with two testers and 12 top crosses) was to estimate , top cross hybrid vigour, effect of GCA and SCA, developing hybrids for high grain yield and other traits. Significant differences were among genotypes and their mating’s in studied traits, except ear number/plant.Hybrid (I ×Agr183) produced higher average number of grain/row (39.50) and grain yield 212.36 g/plant, higher average weight of grain were 31.08/g .The hybrid (T×Wc163) gave higher positive hybrid vigour for best parents and mid parents for weight of grain (13.03% ,17.73%), grain yield (57.52%, 117.98%) for the hybrid (I ×Dekalb243) respectively.Significant difference were found for the effect of GCA.Inbred Agr183 was the best, for the GCA of number of ears/plant, and number of grain/row.Inbred PAN466, was best for the plant height and Dekalb243 best in number of grains/row, weight of grain and grain yield, These results reflect that DEKALB243 had a great contribution in transmitting traits to the hybrid, which share in producing the hybrid (T×PAN466) was higher in number of grains/row and grain yield, the hybrid (I×Xq880), was higher in weight of grain. High value of effect of SCA, pointed out the increasing of averge trait in hybrid production comparing to their parents. Genetic variance dominance values б²D was higher than genetic variance additive values б²A for all traits except grain yield.Higher decrease in narrow sense heritability for all traits, increase of the average of dominance ā than one, except 50% tassiling The higher grain yield obtained was 212.36 g/plant for top cross hybrid (I×Agr183). Dominance Inbred in GCA can be reproduced and used in hybrid breeding after self-pollination with selection for other generations.