Bacterial Inoculation and Co-Inoculation Improves Durum Wheat Productivity in Alkaline Calcareous Soils

Intensive agricultural practices have undeniably reduced soil fertility and crop productivity. Furthermore, alkaline calcareous soils represent a significant challenge for agricultural production, particularly durum wheat, which is vital for ensuring food security. It is therefore essential to explore new cereal management strategies to maintain food production and promote crop sustainability. The application of soil microorganisms, particularly plant growth-promoting rhizobacteria (PGPR), as inoculants to enhance crop production is a growing area of interest. This study investigates the effects of the rhizobacteria Paenibacillus polymyxa SGH1 and SGK2, applied both individually and in combination, on the growth and productivity of durum wheat in alkaline calcareous soil. We conducted fi eld experiments over two growing seasons using a randomized complete block design with three blocks, considering four treatments: non-inoculated wheat grains (T0), inoculation with the P. polymyxa SGH1 strain (T1), inoculation with the P. polymyxa SGK2 strain (T2), and co-inoculation with both strains (T3). The results clearly showed that SGH1 and SGK2 inoculation improved the morphometric characteristics of wheat plants, with co-inoculation of both strains that induced more pronounced improvements compared to T0 in terms of collar diameter (+16.9%), tillers plant-1 (+89.8%), and SA/RA ratio (+35.5%). Co-inoculation was also the most effective treatment for improving the wheat grain yield (+41.1% in season I and + 16.6% in season II). In addition, T3 significantly increased the grain starch content (+220%). T1 determined the highest grain protein content in both seasons (9.5% in season I and 9.66% DW in season II). This study demonstrated that bacterial inoculation and co-inoculation strategies can significantly enhance wheat productivity and grain quality in alkaline calcareous soils while reducing at the same time the ecological footprint of agriculture.