Effet de l’inoculation des céréales par les PGPR et les mycorhizes en condition de déficit hydrique

Abstract

In Algeria, cereal production remains deficient and does not meet growing demand. It is strongly linked on the first hand to climatic conditions, water stress, increased abnormal temperatures, low rainfall and on the other hand to the characteristic of soils which lack nitrogen and phosphorus and all these factors affect and fall yields. Several approaches to improve cereal production are used, among which is the method based on the use of microorganisms such as Plant Growth Promoting Rhizobacteria (PGPR) and arbuscular mycorrhizal fungi which are the main symbiotic components of the soil. These fungal symbiotes are known in the course of the main biogeochemical cycles of soils in the growth of plants by promoting their mineral and hydric nutrients. The aim of this work is to study the diversity of endomycorrhizal spores in durum wheat fields (Triticum durum) in arid, semi-arid and coastal zones. Soil samples were collected from the Algerian eastern wheat patches, the spores were isolated by the wet sieving method and observed under the binocular microscope to sort and count according to color, shape and size. Physico-chemical and catabolic analyzes of soils as well as mycorhization parameters were calculated. The field soil of the semi-arid regions of the eastern region is clayey limono and clay loam, its pH is alkaline (7.54-8.27), the total nitrogen content is (0.023 to 0.082%), Phosphorus are between (1.63% -7.74%). The presence of several morphotypes was noted. The latter are classified as follows: Glomeraceae, Acaulosporaceae, Scutellosporaceae with a predominance of Glomeraceae in the different sites according to the climate and the nature of the soils. The presence of these families demonstrates biodiversity in the plots of wheat in eastern Algeria. Secondly a comparative study on the morphological and biochemical physiological level of the behavior of plants inoculated by mycrosymbiotes of two genotypes of durum wheat, soft wheat, barley and triticale in the presence or absence of water stress Under greenhouse conditions under controlled conditions. Trials were conducted for three years. These genotypes were inoculated with three Frankia Cci3 inocula, Azospirillum brasilense and mycorrhizal spores. After cultivation, the plants were harvested. The growth parameters were measured as well as the dry weight of the plant and roots and the chlorophyll and nitrogen levels.The obtained results are significant. They show that inoculation with mycorrhizal spores (IM) treatment improves the growth of the plant in length of ear leaves and roots. The Azospirillum (AI) treatment has a favorable effect on the nitrogen content accumulated in the leaves of the inoculated plants and the plants inoculated under water stress compared to the control plants