ESTIMATION OF SOME GENETIC PARAMETERS OF THREE-WAY CROSSES OF MAIZE UNDER DIFFERENT SOWING DATES

Abstract

With aim of estimation of some genetic parameters of three-way crosses of maize and testing them under different sowing dates. A field experiment was carried out at Station A in the Department of Field Crops - College of Agricultural Engineering Sciences - University of Baghdad / Al-Jadriyah, for the fall season 2022.The experiment was carried out in a split-plot arrangement according to a randomized complete block design (RCBD) with three replications.The sowing dates (15July, 25July, 5 August) allocated to the main plot, while the six superiorthree-way cross hybrids and the local control cultivar (Fajr 1) represented the sub-plot.The three-way hybrids were obtained from crossing five pure inbred lines of maize, namely ZM43WIZE, ZM60, ZM49W3E, ZM19 and CDCN5.The results showed that the values of standard error SE and the coefficient of variation (C.V) for the studied traits at the three planting dates were low and within acceptable limits, as evidence of the homogeneity of the data.The genetic variance was higher than the environmental variance for most of the studied traits.While the genetic variance was less than the environmental variance for a number of traits studied at the two dates July 25 and August 5.The percentage of heritability in the broad sense (%h2b.s) for the studied traits differed according to the sowing dates,its values were higher than 70% at the date of planting July 15th for the characteristics of 75% tasseling and silking, plant height, leaf area, LAI, ear number, ear number, TDM, CGR, and HI(89.5, 92.1, 85.9, 91.1, 91.1, 80.1, 95.4, 78.8, 74.7, and 84.6%) respectively. Whereas at the second date, the traits that achieved values greater than 70% were leaf area, LAI, ear number, TDM, CGR, plant yield, unit area, and HI (77.0, 77.0, 92.3, 94.8, 93.1, 84.3, 84.3, and 90.4%) respectively.While its values were higher than 70% at the date of planting August 1 for the characteristics of 75% silking, plant height, leaf area, LAI, number of grains per ear, number of ears, weight of 100 grains, TDM, and CGR (77.3, 71.6, 76.8, 76.8, 82.2, and 94.2). And 92.2, 84.5, and 86.4 %) respectively.We propose to study the three-way cross hybrids at sowing dates in the spring season to demonstrate their ability to environmentally adapt to the climate of Iraq, and to test them under abiotic stresses such as drought.