Estimation of Genetic Parameter by Using Full Diallel Cross in Maize under Different Irrigation Interval

Abstract

The research was carried out with the aim of estimating the general and specific capabilities of the coalition and the genetic action of inbred lines of maize The field experiment was carried out in one of the agricultural fields of Al-Khalidiya District - Anbar Governorate - Iraq for the spring season 2019, five inbred lines AG116, AG-M20, MH17, MH121 and ZM4 were used for this study and entered into a full diallel-cross breeding program, and evaluate the behavior of these inbred lines and their diallel and reciprocal crosses according to the first Griffing method and the fixed model. A comparison experiment was carried out between parental inbred lines and diallel and reciprocal hybrids using the RCBD design in split-plot arrangement with three replications. Where the irrigation intervals 6 and 12 days allocated to the main plots, and genotypes (inbred lines and hybrids) allocated to the sub plots in order to estimate the general and specific combining ability of the studied traits. The results of the study indicated that there were significant differences between the parental inbred lines and their diallel and reciprocal hybrids in the general and specific combining abilities and their effects for most of the studied traits. The inbred ZM4 gave the highest negative combining ability to female flowering, which was −0.77 and −1.06 for 6 and 12-day irrigation intervals, respectively. While the MH121 inbred line with 6-day irrigation interval and ZM4 inbred line with 12-day irrigation interval were distinguished by giving it the highest positive and significant combining ability of grain yield, which amounted to 4.78 and 9.45, respectively. The specific combining ability of the hybrids was characterized by negative and positive values, the cross-hybrid AG116 × AGM20 with the irrigation interval of 6 days gave the highest positive and significant combining ability of 34.05. While the hybrid MH17 × ZM4 with an irrigation interval of 12 days was distinguished by giving it a positive combining ability of 7.12. As for the reciprocal hybrids, the reciprocal hybrid MH121 × AG116 with irrigation intervals of 6 and 12 days gave the highest positive and significant values of 48.74 and 25.76, respectively. The percentage of heritability in the broad sense was 99.8% in the leaf area of the 6-day irrigation interval, while with the 12-day irrigation interval it was 98.76% in the female flowering trait. Whereas, the percentages of heritability in the narrow sense reached 78% in the number of rows in ear with the irrigation interval of 6 days for the reciprocal hybrids, while it reached 78.91 in the reciprocal hybrids at the 12-day irrigation interval for female flowering.