GENETICAL STUDIES ON COMBINING ABILITY FOR YIELD AND ITS COMPONENTS TRAITS IN HYBDRID RICE UNDER NORMAL AND SALINE CONDITIONS
Journal of Agricultural Chemistry and Biotechnology
In this study, an effort was made to identify good parents and nature of gene action governing yield and its components characters of rice under normal and saline environmental by Line (three cytoplasmic male sterile) x tester (three restorers) analysis. In the present study, the mean square due to genotypes, parents, crosses and parent vs crosses revealed highly significant variations at locations, years and their combined analysis over locations through years. The interactions of genotypes,
... rents and crosses by years and locations were highly significant for all grain yield and its components traits except 1000-grain weight trait which revealed insignificant interaction over the years. On the other hand the mean squares resulting from the interaction of genotypes, parents and crosses by years × locations were insignificant in all studied traits except number of grains / panicle and the number of filled grains / panicle traits which showed highly significant. GCA for lines and testers and SCA for Lines x testers were highly significant under all environments and combined analysis for yield and its components traits. Similarly, the genetic variance of interaction of lines and testers by years and locations were highly significant. But the mean squares of interaction of lines and testers by years x locations were often insignificant for all traits except number of grains / panicle and number of filled grains / panicle traits which revealed highly significant. Parents with high x high or low x high general combining ability GCA effects gave the best heterotic combination like the 1R70368A / Giza181R. Meanwhile, the CMS line IR70368A was the best female general combining ability for most of studied traits, while, the restorer lines Giza181R and Giza182R were the best testers capable of to combine their genes with the lines for the most studied traits. Also, the cross combinations IR70368A x Giza 181R and IR58025A x Giza 182R showed high SCA effects for most studied traits and considered as the best combinations. The results showed that all yield and its components traits were largely governed by additive gene action except number of panicles / plant which was governed by non-additive gene action, indicating that the additive variance plays the main role in the inheritance of these traits. Furthermore, the magnitude values of additive by years, locations and years x locations interactions were positive and larger than non-additive interactions for all yield traits. Heritability estimates in the narrow and broad senses were close together in value for most yield and its components traits, indicating that the additive genetic variance plays the master role in the inheritance of these traits.