Articles

Effect of moisture stress on combining ability and gene action for polygenic traits in maize


Abstract


Present study was carried out to assess the general combining ability effects of parents and specific combining ability effects of hybrids for yield and yield related traits purely under rainfed situations. Incidently, it mimicked mid season drought conditions i.e. moisture stress at flowering stage for a period of 22 days. Combining ability analy- sis using Line × Tester design was conducted in maize (Zea mays L) inbred lines by growing 135 F ’s generated by crossing fifteen lines with nine testers at ARS, Karimnagar, PJTSAU during rainy season, 2011. Female lines were derived from the recurrent selection cycle carried out in the drought tolerant population «Tuxpeno Sequia», procured from CIMMYT in 1996. Males were developed using pedigree breeding. Analysis of variance showed highly significant genotypic differences for all the traits studied indicating wide range of variability among the geno- types. The ratio of gca /sca was less than unity indicating the preponderance of non-additive gene action in the expression of all the characters studied except flowering traits. Moderate narrow sense heritability was observed for majority of the characters. Three lines KMLD-3, KMLD-11, and KMLD-19 and one tester, KML-9 were good general combiners for grain yield and one or more yield contributing characters. The crosses KMLD-3 × KML-99, KMLD-5 × BML-7, KMLD-5 × KML-801, KMLD-6 × KML-36, and KMLD-11 × KML-29 showed significant positive sca, standard heterosis and high mean values for grain yield plant-1 and two or more yield components. These hybrids were found to be early in flowering with significant negative heterosis providing some clue about their use- fulness under drought conditions. Therefore further testing of these new inbred lines for use in a crossing program is recommended to combine major yield components with high yield to derive climate resilient hybrids.

Keywords

maize, moisture stress, combining ability, line × tester, standard heterosis, narrow sense heritability

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