| To estimate the extent of genetic variability of some maize characters under different plant population, a field experiment was carried out at the experimental field of Dept. of Field Crop science, Coll. of Agric. Univ. of Baghdad during fall 2011 and Spring 2012 using three different populations 47.6, 57.1, and 71.4 thousands plants per ha. The cultivars were Buhoth 106 improved and original. The experiments were factorial and laid out in completely randomized block design with four replicates. Several traits were studied in terms of plants’ performance and variations aspects, observations were recorded on ten plants in each treatment. The values of genetic, environmental variance, genetic and phenotypic coefficient variation, stability and the heritability of maize were calculated .The highest genetic variation environmental variation were 88.3, 57.8, 48.0 and 25.2 for total dry matters, crop growth rate, stalk dimension, and leaf area index respectively, while the lowest rates were 0.7, 3.8, 4.3 for effective filling period, dates to flowering and number of functional leaves correspondingly. The highest heritability was for total dry matters 99% and the lowest was for effective filling period 42%. The highest phenotypic stability was for the dates to flowering and dates to maturity (both 98%) for improved cultivar during fall season. The population density has significantly affected the entire studied traits in both seasons, the improved cultivar was superior in the whole traits under study apart from effective filling period, there was a significant interaction cultivars X population in fall season for the traits of dates to maturity, leaf area index, crop growth rate and total dry matters, while the traits of dates to flowering, effective filling period, plant height and number of functional leaves were non significant. We conclude that some traits are affecting more by the environmental factors; therefore we recommend considering the total dry matters and crop growth rate as a criteria in measuring grains’ production ability of maize. |