Genetical analysis for yield and its attributes in bread wheat using the five parameters model [electronic resource].

Includes references.

The present work was carried out at Etay-Elbaroud Agricult\lre Research Station Behera governorate during four seasons from 2007/2008 to 2010/2011. Three crosses were made among four parents, namely Gemmiza 9 x Irena, Sids 1x Sakha 93 and Sids 1st Irena. Five populations (P₁ P₂ F₁ F₂ and bulk of F₃) for each cross were used in this investigation. Highly Significant positive heterotic effect was found in the 2nd cross for grain yield and its attributes Le., number of spikes/plant, number of kernels/spike and 1000-kemel weight and grain yield/plant, being 8.69%, 9.78%, 6.71% and 9.78% in the same respective order. Meanwhile, Negative significant heterotic effects were obtained in the 3rd cross for both number of spikeslplant (17.45%) and number of kernels/spike -3.08% led to a reduction in grain yield/plant with a value being (-10.37%). Complete dominance was found for number of spikes/ plant and 100-kemel weight in the first cross whereas, overdominance (p>1) was detected for grain yield and its attributes in the 2nd cross. The other types of dominance were also found. Inbreeding depression estimates were significant with a positive value for number of spikes/ plant in the first and third cross, number of kernels/ spike and grain yield/ plant in all crosses. On the other side, inbreeding depression was negatively significant for number of spikes/ plant in the second cross and for 100-kernel weight in the second and third cross. Additive gene effects were positive and significant for number of kernels/spike in the second and third cross and 100-kernel weight in the first cross. Dominance gene effects were found to be significant for all studied characters with the exception of number of kernels/spike in the first and second cross indicating that dominance played a major roie in the inheritance of such characters. Significant and positive (E₁) values were found for 100-kernel weight in the studied crosses. While, negative values were obtained for number of spikes/ plant in the third cross, number of kernels/ spike in all crosses, and grain yield/plant in the second and third cross. Moreover, (E₂) values were found to be positive and significant for 100kernel weight in the third cross only. On the other hand, significant negative (E₂) values were detected for number of spikes! plant and number of kernels! spike in the three crosses, for 100-kemel weight in the second cross, and grain yield/plant in both the second and third cross. Narrow sense heritability estimates were ranged from 39.35% for number of spikes /plant in the third cross to 94.32% for grain yield/plant in the second one. The parent-off spring regression heritability estimates were high and ranged from 58.85% for number of spikes/ plant in the third cross to 95.65% for grain yieldl plant in the second one. The expected genetic advance (Ag) for number of spikes/ plant was ranged from 3.87 to 10.17 for the selected 5% of F2 compared with the actual genetic gain which was ranged from 5.07 to 9.37 in the studied crosses. Meanwhile, the expected gain for grain yield/plant was ranged from 21.05 to 36.26 gm.whereas, the actual gain was ranged from 18.46 to 26.81 gm.

Summary in Arabic.

1