Variability of Rhizosphere Microbial Biomass, Mineral Nutrients, and Yield Performance as Affected by Durum Wheat Cultivars and Water Salinity Irrigation

Durum wheat salinity tolerance under the effect of rhizosphere microorganisms was investigated in situ in semi-arid areas using contrasted irrigation water salinity (6 and 12 dS m-1). Six durum wheat cultivars were tested: three landraces (“Bayadha”, “Souri”, and “Agili Glabre”) and three modern varieties (“Razzek”, “Karim”, and “Maali”). The microbial biomass carbon (MBC), mineral nitrogen (MN), mineral phosphorus (MP), and grain yield (GY) and its components, were under durum wheat genotypic effect under salinity stress. Interestingly, soil biota of the cultivars “Agili Glabre” and “Maali” increased under saline conditions (12 dS m-1) mainly at tillering growth stage. The principal component analysis discriminated “Agili Glabre” from other cultivars with higher MBC and MP under saline conditions. Stepwise regression analysis showed that predictors of GY depend on salinity conditions, cultivars (landraces or modern varieties), and growth stage. Overall, the present study revealed the importance of microbial activity (MBC) and MP at tillering and flowering growth stages. These two parameters might be considered as effective indicators to assess durum wheat genotypic performance to salinity tolerance.