REPONSES MORPHO-PHYSIOLOGIQUES ET BIOCHIMIQUES DE LA SYMBIOSE RHIZOBIA-ARACHIDE AU STRESS HYDRIQUE

Abstract

Despite the level of resistance sizable developed by peanut (Arachis hypogaea L.) production in the dry ecosystems is affected by periods of water deficit occurring during the growth cycle. The purpose of this work was to highlight the responses to water deficit low, moderate and severe of five peanut populations of local and foreign origin were inoculated by three rhizobiens strains, to identify criteria for selecting symbiotic interactions better adapted to drought. Water stress was imposed by withholding water at the floral initiation stage. The mechanisms studied focused on the morpho-physiological aspects (height of the stem, leaf area, content of proline and soluble sugar, relative water content, leaf water potential, stomatal resistance and leaf temperature), biochemical aspects (fixation and assimilation of nitrogen) and agronomical aspects (yield and its components). During the stress treatment, relative water content and leaf water potential decreased and stomatal resistance, leaf temperature increased in all symbiotic interactions. Water stress also increased sugar and proline concentrations and decreased the assimilation and fixation of nitrogen. All these effects of water impact negatively on the vegetative growth and on yield and its components. The symbiotic interactions studied behave differently depending on the severity of water stress. However, symbiotic interactions SA3-BER, SA3-OUM, SA3-TON, SA3-TIM, SA1-BER, SA1-TON and SA1-OUM proved the most tolerant to different degrees of water stress applied. As against the symbiotic interactions SA2-TIM and SA2-NIG showed a significant sensitivity over the lack of water. The behavior of other symbiotic interactions varied depending on the severity of stress applied. Moreover, the genetic variability of plant material in relation to water stress does not appear related to the geographical origin of populations of peanut, but rather to their phenology and morphology. This study could serve to define criteria for resistance to drought used in breeding.