خصائص ل . U.P.O.Vوالتنوع عند الحبوب ذات السيقان التبنية ) :(Triticum et Hordeumمحاولة خلق تنوعية جديدة.

Abstract

The main objective of our study, as stipulated in the title of the thesis, is to contribute methodologically to the creation of genetic variability while targeting the particular elements of parents, characters easy to distinguish in order to be able to observe them easily appear in the descendants. To do this, we started by characterizing the parental genotypes of the three species under study (T.durum Desf., T.aestivum L., H.vulgare L.) and by evaluating the morphophenological and physiological characters through the creation of descriptive sheets according to the recommendations of the U.P.O.V to know the amount of the genetic variability in order to choose the appropriate methods before to launch in improvement programs. The experiment was carried out in a glass greenhouse at the Bio-pôle of the Laboratory for the Development and Valorization of Plant Genetic Resources in Chaâb Erassas, University of the Mentouri brothers Constantine 1, for five seasons. The results obtained and related to the parents showed a significant difference between the genotypes of each species through the phenology, the descriptive sheets and the characters of production and adaptation. These results suggest that hybrids from these parents will be highly different from each other. Once this step is performed, A half-diallel crosses are undertaken between the parents judged to be better for creating a new variability and of proceed for the comparison the genetic potential of four (4) durum wheat cultivars, four (4) bread wheat and five (5) barley with their F1 hybrids as well as, the hybrid of second generation (F2) for durum wheat. The parental genotypes and their hybrids are then sown in a complete randomized blocks design with three repetitions in half-diallel following method 2 and Model 1 of Griffing (1956). The results of the first generation of each species indicated the importance of the additive and non-additive effects in the inheritance of traits under study with the preponderance of additive gene effects for the spike length with beards, the length of beard and the number of nodes per plant. The two effects of additive and nonadditive genes are equal to the of spike length in barley. The effects of additive genes were observed in heredity of the neck spike length, plant height, spike length with barbs, the length of beard, the number of spikelets per spike, the fertility of the spike and the number of grains per spike at common wheat, while controlling flag leaf area, spike length in the first generation of durum wheat and the number of nodes per plant in the second generation (F2). Non-additive gene effects were recorded for the rest of the traits studied. The parents Rihane 03 and Akhrash of barley, TSI \ VEE and Florence aurore of bread wheat and Djeneh - Khataifa, Guemgoum Rekham in durum wheat have recorded in F1the best significant values for general combining ability (GCA) for some characters of production and adaptation. The same observation was noted in F2 for the same genotypes of durum wheat. It is therefore suggested to use these parents in cereal breeding programs because of their ability to inherit these traits from to their descendants. Several hybrids record positive values of specific combining ability (SCA) due to additive X additive genetic interaction and present the highest values of heterosis in F1. These are the hybrids Akhrash x Beecher10, Jaidor x Akhrash in the barley, TSI \ VEE X Mexipak in bread wheat and Djeneh-Khetaifa x Guemgoum Rekham in durum wheat. The value of heterosis decreases certainly in F2, but remains in favor of the hybrid Djeneh –Khetaifa x Guemgoum Rekham. While the F2 generation of hybrids Béliouni x Guemgoum Rekham and Béliouni X Djeneh –Khetaifa are distinguished by the highest positive values of specific combining ability and a important heterosis effects. These hybrids can be adopted as new genotypes inheriting the traits of production and adaptation, hence the interest of continuing their selection in isolated generations to reach pure lines cultivated in fixed varieties. The study of heritability in the narrow sense showed strong values in half of the characters studied for barley and in thirteen (13) traits of common wheat and four (4) traits for durum wheat in the first generation and one trait for the second generation, while, heritability values in the broad sense are high for most traits studied in the three species. Keyword : Triticum, Hordeum, Diversity, Variability , half dialel cross, GCA, SCA, Heterosis.