الفهرس 
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Abstract
This study was carried out to determine the genetic diversity among ten maize inbred lines using Random Amplified Polymorphic DNA (RAPD) technique with five primers, also estimate combining ability and their interaction with planting dates, heterosis and compute correlation and factor analyses for some important traits of maize. The 45 single crosses resulted from the ten inbred lines along with two checks (S.C.10 and S.C. 30k8) were evaluated in two different planting dates (May, 15th and June 15th). The five RAPD markers produced sixty three amplified fragments among which forty eight were found polymorphic with 72.6% polymorphism. The lowest genetic similarity was detected between the two parental lines P6 (M14) x P8 (M20) lines. Mean squares due to planting dates along with crosses were significant for all studied traits in both planting dates and combined analyses. The single cross P6 (M14) x P8 (M20) gave the best mean values for grain yield plant-1 and most of its components. General combining ability mean squares appeared to play important role than specific combining ability ones in controlling most studied traits. Parental inbred line P6 (M14) was the best general combiner for number of rows ear-1, grain yield plant-1, and grain yield plot-1. Parental inbred line P8 (M20) was the best general combiner for ear length, and number of grains row-1 in the combined data. The most desirable SCA effects were detected for the cross P6 (M14) x P8 (M20) for chlorophyll content, ear length, number of rows ear-1, number of grains row-1, grain yield plant-1, and grain yield plot-1, and P6 (M14) x P10 (M24) for 100 kernel weight. The best heterotic effects were detected for the cross P6 (M14) x P8 (M20) for ear length, number of rows ear-1, number of grains row-1, 100 kernel weight, grain yield plant-1, and grain yield plot-1, P5 (M12) x P6 (M14) for days to 50% tasseling and chlorophyll content, P1 (M2) x P8 (M20) for plant and ear heights, P4 (M10) x P7 (M19) for protein% and P1 (M2) x P2 (M3) for oil% relative to both checks in the combined analyses. Highly significant and positive correlation coefficients were detected between grain yield plant-1 and each of chlorophyll content, ear length, ear diameter, number of rows ear-1, number of grains row-1, 100 grain weight and shelling % in the combined analyses of both planting dates. The factor analysis technique divided the studied variables into four main factors accounted for 77.83% of the total variance in the combined analyses. The first factor included four variables i.e., ear length, number of rows ear-1, number of grains row-1 and shelling % and accounted for 21.15 %. While, the second factor consisted of two variables i.e., plant and ear heights and accounted for 19.73% of the total variance. The third factor included two variables namely, days to 50% tasseling and silking and accounted for 19.00% of total variance. Three variables were loaded in the fourth factor i.e., chlorophyll content, ear diameter and 100 grain weight and accounted for 17.95% of the total variance of the dependence structure.