A field experiment was carried out in the fields of the Field Crops Department - Faculty of Agricultural Engineering Sciences. The study included five inbred lines (ZM43W (ZE), ZM60, ZM49W3E, ZM19, CDCN5), given numbers 1, 2, 3, 4 and 5) to study the hybrid vigor and both general and special combing ability (GCA, SCA) of the half diallel mating method, for the spring and fall seasons (2016). The genetic analysis shows that all crosses gave a positive hybrid vigor for grain yield per unit area at the two population densities. the highest value is 116.20% for cross (3´5 )at low density, and 89.22% for cross( 1´4 )at high density. The hybrid vigor for all crosses is positive at two densities for dry matter yield, crop growth rate and ears weight. The highest value is 81.31%, 96.30% and 131.45% at high density for these traits for the cross (1´2), respectively. Also, this cross gave the highest value at high density for grain yield per plant (170.61%) and (85.43%) for no. of grain plant-1. The general combining ability in two densities for all studied traits. The highest positive value was (48.949) for parent 3 at low density. All values of s2sca are more than values of s2gca, and all values of s2D are more than all values of s2A. For this, all h2n.s. were low. It ranges from 1.88% for the crop growth rate to 18.82% for no. of rows ear-1 at low density and between -0.38 for the crop growth rate to 41.42 for 300-grain weight at high density. Because the values of s2D are higher than values of s2A, the values of the ratio of s2gca/s2gsca were less than one, while the value of were mor than one. This indicates that all these traits are influenced by dominance genes, and the importance of the non-additive gene action and its large contribution to the inheritance of these traits. Keywords: maize, combining ability, heritability, genetic parameters.

The purpose of this experiment was to determine the relationship between the path coefficient and seed rate for four different barley cultivars (Amal, Ibaa 265, Ibaa 99, and Buhooth 244) during the 2019-2020 winter season. The experiment was carried out using a split plot design with three replications according to a randomized complete block design (RCBD). The highest positive thru effect on grain yield was found for flag leaf area and harvest index at aseeding rate of 130 kg.h-1; the highest positive direct effect on grain yield was found for flag leaf area and plant height at aseeding rate of 160 kg.h-1; and the highest positive direct effect on yield was found for biological yield and harvest index at a seeding rate of 190 kg.ha-1. Because of this, it can be used as proof of selective breeding for increased yield in barley by plant breeders.

to This study was carried out in the field of the College of Agricultural Engineering Sciences - University of Baghdad - Jadriya in the win-ter season 2019-2020 in order to study the genetic correlations of four varieties of barley (Amal, Ibaa 265, Ibaa 99, and Research 244) with the effect of three seed rates (130, 160 and 190 kg ha_1). The experiment was applied using the split plot design and with three replications according to the randomized complete block design. The main plots included three seeding rates, while the Sub-plots in-cluded four varieties. The results showed that the genetic correlation was positive and highly significant between the traits of the number of spikes and the trait of the number of grains in the spike with the grain yield and for all seeding rates, so that plant breeders can rely on them as a selective evidence for high yield in barley

The objectives of this experiment were to evaluate the performance of two varieties of sunflower (Helianthus annuus L.)  with three plant densities (40, 50 and  60 thousands of  plants.ha-1.)  and estimate the phenotypic, genotypic and environment variation, phenotypic and genotypic coefficient of variation, heritability, stability and genetic resultant, for two seasons. The experiments were conducted during spring and fall seasons of 2013, using factorial experiment within RCBD with four replicates. The results showed the superiority of Shimoos variety, it gives seed yield 3.345 t.ha-1 compared with Aqmar variety which gave 2.375 t.ha-1 in spring season, at fall season Shimoos variety gave 6.265 t.ha-1, while Aqmar variety gave 5.379 t.ha-1. The yield increased with plant density increasing, it ranged from 2.425 to 3.222t.ha-1 in spring season and from 4.396 to 5.822t.ha-1 in fall season. The values of phenotypic stability were different according to differences between varieties and seasons. The high value was 93.75% for disc area followed by 90.13% for seed yield t.ha-1 for Aqmar in spring season and the higher value for Shimoos variety was 94.15 for disc area followed by 90.66% and 90.55% for 100 seed weight and number of seeds in disc respectively. . All values of genetic variation are higher than environment variation, and were closed to phenotypic variations for spring and fall seasons, except for seed number in disc in fall season which was less than environment variation. Hence the heritability for these traits were high and ranges from 63% for seed number in disc to 95% for shoot dry weight in spring season and from 33% for seed number in disc to 99.6% for disc area in fall season. So the genetic coefficient of variation for all traits is closed to phenotypic coefficient variation. The traits: plant growth rate and shoot dry weight for Aqmar, and leaf area index, plant growth rate and seeds yield for Shimoos showed non phenotypic stability in spring season. In fall season, seed yield t.ha-1 for Aqmar was the only trait non-phenotypic stable. The genetic results are ranged from 65.32% for shoot dry weight to 98.86% for seed number in disc for Aqmar and from 81.34% for seed number in disc to 114.79% for 100 seed weight for Shimoos in spring. In fall season, it ranges from 69.18 for leaf area index to 96.02% for seed number in disc for Aqmar and from 89.25% for seed number in disc to 107.32% for disc area for ShimoosIt is possible to conclude that Shimoos variety was superior in most of the traits. So we recommend planting Shimoos variety in the fall season, because it is more stable than Aqmar variety, while Aqmar variety can be cultivated in the spring season.