Diversité biologique, biochimique, phytochimique et génétique chez deux genres de céréales (Triticum et Hordeum).

Abstract

This study was conducted at the Experimental Station of the Technical Institute of Field Crops (I.T.G.C.) of El Khroub, wilaya of Constantine during the two agricultural campaigns ; 2017/2018 and 2018/2019. The aim of this investigation was, on the one hand, to assess the biological diversity in two cereal genera (Triticum and Hordeum) in order to identify the basic traits that can be exploited in improving these cereals. On the other hand, to analyze and highlight the various links recorded between the studied parameters, which can make a contribution to the applied programs for improving both productivity and adaptation of these cereals. In fact, the present study provided an overview on the nine studied varieties’ behaviors, in relation to the environmental conditions, to distinguish the most efficient and the least affected varieties by these experimental constraints. The obtained results, supported by the carried out statistical analyses, clearly revealed a significant genotypic variation for all the tested characteristics, those indicated by the existence of significant intra- and inter-species variability ; which must be preserved and improved ; so it can be used in programs to improve the productivity and the adaptation. The principal component analysis (PCA) generated the variation of the two agricultural compaigns with an optimal rate of information equal to 72.83, 85.30, and 85.08% in the three species T. durum, T. aestivum, and Hordeum vulgare ; respectively. This information presents a good basis for interpreting the typology of the evaluated varieties and the relationships between their different measured variables. Besides, it was also shown that the grain yield is positively related with its components ; the surface of the flag leaf and the content of the leaves in chlorophyll pigment. While adaptation and tolerance to stress are related to early onset of heading, plant height, relative water content, leaves osmolyte and secondary metabolites content, as well as level of cellular damage. Indirect selection via these traits can be beneficial for breeding and adaptation programs. On the whole, the three varieties ; GTA dur of durum wheat, ARZ of bread wheat, and Fouara of barley revealed the best production characteristics during the two studied periods and can therefore be proposed in the regions of cereal production. While Bousselem, Hidhab, and Saida varieties have proven to be more stable and have the potential to minimize variation in grain yield. These varieties can be recommended for several agro-climatic zones. However, the other studied varieties (Vitron, Ain abid, and Barbe rousse) have shown the advantage of tolerating stresses and are, therefore, recommended for restrictive and less favorable environments. Besides, the analysis of the total grain proteins in the two genera (Triticum and Hordeum), by the electrophoresis technique (SDS-PAGE) during the two compaigns of study, demonstrated a considerable polymorphism equal to 75, 84.21, and 83.33% for the three species T. durum, T. aestivum, and Hordeum vulgare; consecutively, under favorable conditions during the first campaign. On the contrary, in more severe conditions in the second compaign, this polymorphism was decreased recording a rate of 52.94, 42.85, and 68.75% in the three species, successively. This finding is clearly illustrated by the profiles and the ascending hierarchical classification (AHC) of the obtained grain proteins in the different varieties, in which the difference in the number of protein bands, their molecular weights, their densities, the structuring of the proteins groups, and the positioning of the varieties in the two agricultural campaigns was revealed. This analysis exhibited the existence of genotypic variability for the total grain proteins. This latter can therefore constitute potential criteria for improvement and open up new perspectives for breeders. In fact, this investigation allowed to conclude that in order to better control the productivity and the adaptation of cereals in both arid and semi-arid areas, it is necessary to characterize the production environment in a complete and a precise way; to identify the most frequent stresses; in which the culture is subjected. In addition to good management of established technical itineraries and acquisition of deeper knowledge of plants diversity and behavior under stressful conditions; in order to obtain more productive, better adapted, and more regular varieties.