Effect of combining ability for indicators of infection of wheat galls nematode and yield in the second generation of bread wheat genotypes Triticum aestivum L.

A field experiment was carried out in the fields of a farmer in Kirkuk governorate / Hawija district N 43º36´17.73"E"05.56´ 35º16, in the winter season of 2020, and the study included a sensitivity test for 55 genotypes represented by (10 genotypes and 45 hybrids in the second generation) for galls disease Wheat, the experiment was carried out according to the Randomized Complete Blocks Design (RCBD), the results of the analysis of variance for the two general and specific abilities showed that there were significant differences for genotypes in all studied traits, that the best parents with general combining ability and in the desired directionare the parent (Kauz). For the characteristics of the percentage of inactive tillers, the number of spikes of the plant, the number of grains of the spike, the weight of 1000 grains, the yield of the individual plant, and the parent (Site Mall) for the characteristics of the number of spikes of the plant, the number of grains of the spike, the yield of the individual plant, the percentage of infected spikes, the percentage of infected grains and the average weight of the gall The following hybrids (Kauz x Abu Ghraib and Clack x Abu Ghraib and Milan x Abu Ghraib and Site Mall x Kauz and Flurka x Kauz and Clack x Oasis and Milan x Oasis and Sham 6 x Site Mall and Hidab x Flurka and Iba 99 x Flurka and Hidab x clack and Sham 6 x clack and Hidab x Milan and Iba 99 x Milan and Sham 6 x Iba 99), in most of the studied traits of the combining special ability, the traits are the percentage of inactive tillers, the number of spikes of the plant, the weight of 1000 grains and the yield of the individual plant. It was with additional variance higher than the dominance, as it was found that there is partial dominance, the heritability in the narrow sense was high for the characteristics of the percentage of inactive tillers, the number of spikes of the plant, the weight of 1000 grains and the yield of the individual plant, and its value ranged from 0.51 to 0.65, while the trait of the number of grains was recorded The spike, the percentage of infected spikes, the percentage of infected grains, and the average gall weight (mg), heritability ranged from 0.37 to 0.46. The expected genetic improvement as a percentage was high for all studied traits except for the number of spike grains and the weight of 1000 grains. The average genetic improvement was 21.73 and 27.66%, respectively