GENE ACTION AND INHERITANCE OF SOME QUANTITATIVE AND QUALITATIVE TRAITS IN THREE BREAD WHEAT CROSSES

Abstract

The six populations i.e., P1, P2, F1, F2, BCI and BCII of the threecrosses (Sids 4 x Sids 1) (Sids 1x Giza 168) and (Giza 168x Gemmeiza9) were used to estimate genetic variance, gene action, heterosis,inbreeding depression, heritability and genetic advance for the days toheading, days to maturity and plant height as well as yield and itscomponents traits. The experiment was conducted at Sids Agric. Res.Stan. (Beni suef governorate) during the three successive growingseasons 2003 / 2004, 2004 / 2005 and 2005 / 2006.Significant positiveheterosis effects relative to mid parent values were obtained for numberof spikelets / spike, number of kernels / spike, grain yield / spike andgrain yield / plant in the three crosses and for 1000-kernel weight in the2nd and 3rd cross. Significant negative heterosis effects were found fordays to heading, days to maturity and plant height in the three crosses,and for number of spikes / plant in the 2nd cross. Significant negativeinbreeding depression were detected for days to heading, days tomaturity and number of spikes / plant in the three crosses, for plantheight in the 2nd and 3rd crosses and for1000-kernel weight in the 1st and3rd crosses. Significant positive inbreeding depression were obtained fornumber of spikelets /spike, number of kernels / spike and grain yield /spike in the three crosses, for 1000-kernel weight in the 2nd cross andfor grain yield / plant in the 2nd and 3rd cross. The additive type of geneaction was significant either positive or negative for all traits except daysto heading, days to maturity and1000-kernel weight in the 3rd cross, plantheight, number of spikelets/ spike and grain yield / spike in the 2nd and3rd crosses and grain yield / plant in the 2nd cross. Dominance effectswere significant either positive or negative for all traits except plantheight, number of spikelets / spike and 1000-kernel weight in the 3rdcross, number of spikes / plant in the 2nd cross and grain yield / spike inthe 1st cross. The additive x additive gene effects were significant for allstudied traits except plant height in the 1st and 3rd crosses, number ofspikes / plant in the 1st cross as well as number of spikelets / spike and1000- kernel weight in the 3rd cross. The additive x dominance geneeffects exhibited significant for the majority traits except days to headingin the 2nd cross, plant height and number of spikelets / spike and 1000-kernel weight in the 3rd crosses and grain yield / spike in the 2nd and 3rdcrosses. The dominance x dominance gene effects were found to besignificant either positive or negative for all traits expect plant height in the 3rd cross. High to moderate heritability values in broad sense weredetected for most studied traits. Moderate heritability values in narrowsense were detected for most studied traits except tw cases. These resultsascertained that both additive and non–additive genetic variance wereimportant in the existence of variability in these traits.