In winter wheat breeding, progress in development of improved germplasm depends primarily on availability of valuable genetic material, right selection of parents for crosses and the knowledge of inheritance pattern for the most valuable traits for assessing the segregating populations. More than 100 combinations were used in crosses including a set of the local varieties and lines supplied by CIMMYT to produce improved germplasm with desired agronomic traits. The study ofthe F1 population detected true heterosis of various extent ( 1.5-42.5% ) for different parent combinations and for different traits. High true heterosis (35.7-42.5%) was observed for grain per spike and tillering in the populations obtained from crosses with participation of the CIMMYT - derived lines. Populations developed from crosses between the local varieties demonstrated high heterosis for grain weight per main spike and thousand-grain weight. A study of correlation between individual traits provided evidence that association between main spike height and number of grains per main spike is insignificant and varies between 0.06 and 0.21. Significant negative association (¡=-0.59-0.65) was found between number and weight of grain per spike in the populations obtained from the crosses ofthe CIMMYT -derived lines. In contrast, number of grain per spike and 1000 kernel weight were found to be positively associated (¡= 0.49-0.65) in the populations developed from crosses of the local varieties. Different inheritance patterns were observed for the quantitative traits in the first generation populations. Inheritance depended on their expression in the parental lines and ranged from dominance or over-dominance to depression. However, analysis of a big number of the first generation populations provided evidence that tillering, spike length, grain number and weight per spike are generally characterized by dominance and over-dominance, while stem height, spike length and 1000 kemel weight demonstrated codominance. It should be noted that high spike productivity Of the hybrids was conditioned by higher values of grain per spike in some cases and higher grain weight in other cases. The most valuable combinations were found to be those where high values of grain per spike were combined with high grain weight, affecting positively 1000 kemel-weight and total grain yield. The phenotypic expression of individual traits in the F 2 populations revealed a wide range of variation. The lowest variability was found for spike length. The highest variation factor was detected for number of grain per spike (V= 18.3-4 7.2% ) and weight of grain per spike (V=24.5-58.4%). This facilitates selection of transgressive segregants and their utilization in breeding for higher yield. Crosses with participation of the local varieties "Aran", " Azeri", (Mirbashir- 128), "Murov- 2" and others provided for a larger number of recombinants with optimal combination of higher number of grain per spike and desired plant height.

English

0407|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection