Genetic Analysis by Using Partial Diallel Crossing of Maize In High Plant Densities (Estimation GCA, SCA and Some Genetic Parameters)

Abstract

The experiment was carried out at the Field Crops Research Station, College of Agricultural Engineering Sciences - University of Baghdad in Jadiriyah, with the aim of evaluating the performance of partial diallel hybrids and inbred lines of maize and estimating general combining ability(GCA), specific combining ability (SCA) and some genetic parameters. The experiment was carried out in two seasons, spring and fall 2020. Eight inbred lines of maize were used in the study (BI9/834, BSW18, LW/5 L8/844, ZA17W194, Z117W, ZI17W9, ZI7W4), numbered (1,2,3,4,5,6,7,8), It was sowed in the spring season and entered into a cross-program according to a partial diallel crossing system to obtain twelve partially cross-hybrids, and it was compared with its eight parents in a comparison experiment in the fall season using a Randomized Complete Block Design (RCBD) with split plots arrangement with three replication. The plant densities of 70 and 90 thousand plants ha-1 represented the main plots, while the partial diallel hybrids and their parents represented the secondary plots. The results of the study showed that the ratio between GCA and SCA) GCA/SCA) It was more than 1 for yield traits, ear length, number of rows and number of row grains in both low and high densities, which indicates the control of the additive genetic action on these traits. While the ratio was less than one for the traits of the ear diameter under the low density, which indicates the control of dominance genes on this trait in the mentioned density, while the trait of the number of ear grains, the ratio between the general and specific combining abilities was less than one in the high density. Inbred line 8 had the highest effect for the general ability to combine under low density, which amounted to 11.075, while inbred line 2 was superior by giving the highest effect to the general ability to combine at low density, which amounted to 17.80, followed by inbred 8.

Study of Yield and Its Components of Introduced Varieties of Maize Under Different Planting Densities

“…Plant densities (plant ha ‫املستهلك‬ ‫ية‬ ‫ومحا‬ ‫لسىق‬ ‫ا‬ ‫لبحىث‬ ‫لعراقية‬ ‫ا‬ ‫اجمللة‬ them, as the trait of weight of 100 grains was significantly affected by the difference of plant densities, and the low plant density plants (50,000 plants ha -1 ) outperformed the trait of weight of 100 grains, with an average reached 31.65 g, and did not differ significantly from high density plants, The reason for its superiority is due to the fact that its plants were early in male and female flowering, so the plants of low density were characterized by a long grain filling period and thus gave the weight of 100 grains heavier. These results are in agreement with the findings of Al-Mowsawi ( 2019 As for the traits, (Table , 6) shows that they differed significantly among them, as the introduced variety 4 achieved the highest average weight of 100 grains that reached 34.04 g, and did not differ significantly from the introduced variety 3, which gave an average of 33.11 g, while the local variety Al-Maha gave the less average weight of 100 grains was 28.19 g, The reason for the superiority of the introduced trait 4 by giving it the highest average weight of 100 grains is attributed to the superiority of this trait in the length of grain filling period, as well as the genetic factors that characterize the trait and its impact on environmental factors. These results confirm the findings of Kazem (2020); Amanah (2021); Hamdi & AL-Rawi (2021).…”

“…As for the interaction, (Table , 6) shows that the response of the introduced varieties and the local varieties to plant densities was different, and the response of the introduced varieties was similar towards a decrease in the weight of 100 grains with an increase in the plant density, and that the decrease in the weight of the grains was not significant with an increase in the density from 50000 to 70000 plants ha -1 , Then it was increased from 70,000 to 90,000 plants ha -1 , while the response of local traits was fluctuating, as the local variety Fajr showed the same behavior as the introduced varieties , but its response was significant when the plant density was increased from 70,000 plants ha -1 to 90,000 plants ha -1 , while the two local varieties, Al Maha and Sarah, exhibited a different behavior, the weight of 100 grains increased with an increase in plant density.…”

“…As for the interaction, (Table , 5) shows that the response of the introduced traits and the local traits to the plant densities was different and fluctuating, and most of them showed a decrease in the number of ears plant -1 when the plant density increased, and the response (decrease) from low density to high density was 0.1 for traits 2, 3, 4 and Al-Maha sequentially, with a decrease of 8.33, 7.70, 9.09 and 9.09%, respectively, as the highest average number of ears plant -1 was 1.30 ears plant -1 , at low density of the introduced variety 3, while the lowest average number of ears plant -1 was 1.00 ears plant -1 . At high density (90,000 plants ha -1 ), for the introduced trait 4 and for the two local traits , Al Maha and Sarah.…”

Performance of some Three-Way Cross Hybrids and Their Parents of Maize in the Middle Region of Iraq

“…Heterosis is the excess in size, growth, fertility, yield and resistance to biotic or a biotic stresses in offspring compared with their inbred parents [13] . The extent of heterosis provides information on scope of genetic variety of parents in developing superior offspring to utilize hybrid vigor and has direct effect on the breeding methodology [14] . Heterosis is an efficacious tool for exploitation the potential of inbreds and this depends on the direction and amount of heterosis and also the type of gene action [15].…”

Study of the Genetic Diversity of Some Genotypes of Maize Under Two Levels of Nitrogen Fertilization

“…The maize crop has a wider genetic base and is highly adaptable to various environments, making it a model crop for genetic mechanism studies (Al-Naggar et al, 2022). The highest genetic and phenotypic heterogeneity is also characteristic of maize (Boonlertnirun et al, 2012;Amanah and Hadi, 2021).…”