ESTIMATION OF COMBINING ABILITY AND GENE ACTION OF MAIZE (ZEA MAYS L.) LINES USING LINE×TESTER CROSSES.

A field study was conducted at the Agriculture Research Station in Abu Ghraib, during spring season 2018. Eight strains of corn (Zea mays L.) were provided from the same station to be used in the study (i.e., Sxn.22, MGW.11, and lnb.17, Inb.23, O.7, Am.63, Zm.69 and S.17) have numbers (1, 2, 3, 4, 5, 6, 7, and 8) consequently. Five lines were crossed with three testers to produce 15 individual hybrid, the seeds of hybrid were cultivated in comparison experiment by using Randomize Complete Block Design (R.C.B.D), with three replications to determine the best strains and their individual hybrids, depending on its performance, genetic analysis (GA) for General and Specific Combining Ability (GCA; SCA) and Gene Action (GA), in addition to determine some genetic characteristics i.e., Plant Height (PLH), Leaf Area (LA),Number of Ears Per Plant (NEPP), Number of Rows Per Ear (NRPE), Number of Grains Per Row (NGPR), Weight of 250 Grains (250 WGHT) and Total Grains’ Yield per plant (TGY). The results of statistical analysis showed high significant differences between genotypes (parents + hybrids) for all studied traits. The strain 5 had the highest mean related to PLH and 250 WGHT while the strain 1 was the best in terms of LA, NRPE, NGPR and TGY. Regarding to the tester, the tester (8) was the best in terms of TGY, NEPP, NRPE and NGPR. Regarding to hybrids, the crossed 2 x 6 was the best in related to NEPP, NRPE and TGY per plant. The results of genetic analysis also showed highly significant differences for the mean of squares for GCA and SCA for all traits under study except NRPE, NGPR and TGY per plant that were insignificant for the GCA. Strain 1 showed the best effect of desired trend GCA for TGY and the most studied traits. The cross 2 × 6 had the highest positive effect for SCA related to TGY trait. Furthermore, the percentage of GCA and SCA variance was less than one in all studied traits. The value of broad sense heritability was high in all studied traits except the NGPR, which was low value, while the narrow sense heritability percentage was with low value.in addition to; the average degree of dominance was more than one for all studied traits. [ABSTRACT FROM AUTHOR]