PHENOTYPIC ARIATIONS OF MAIZE CMS POPULATIONS AND SUBPOPULATIONS 2- YIELD TRAITS

Abstract

A study was accomplished to evaluate the contributions of selection and selfing in changing gene frequencies and genetic distinctness. Eighteen cms maize (Zea mays L.) populations were grown for six seasons during 2008-2010 at the field of Crop Science Dept./College of Agriculture. After three cycles of selection and selfing subpopulations retained significant reduction in means for most of the studied traits. Populations showed highly significant differences for all studied traits. The kernel weight reached its maximal values of 28.05g and 26.16g in A5o and R5o populations, and the hybrid A5sxR1o showed its maximal value in hybrids (32.03g). Genetic variability among parent populations concerning kernel weight results in different levels of hybrid vigor with hybrid phenotypes, which were of 83.38% greater than the best parent for the hybrid A5sxR6o. The highest yielding parent populations were of 62.35g and 101.3g for A1o from lines and R2o from tester populations, respectively. The hybrid combination A6sxR3o gave the highest mean for plant yield (141.5g). Selection was efficient in increasing hybrid vigor showed by some parental combinations, while it was acted differently as it reduced the ability of some populations to combine positively. However, hybrid vigor effects regarding the best parent were significant and A3sxR6s possessed its maximal value for plant yield which was 190.98%. Selection and selfing resulted in detectable alterations regarding the performance of populations per se and their ability to combine during hybridization process. These results were supportive to derive version lines with improved attitude.