Moisture- and period-dependent interactive effects of plant growth-promoting rhizobacteria and AM fungus on water use and yield formation in dryland wheat

Abstract

Abstract Purpose In drought-prone soils, plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungus (AMF) might positively affect water uptake and crop yield via rhizosphere interactions. Methods Sole and combined additions of Bacillus amyloliquefaciens producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and Rhizophagus irregularis into rhizospheric soils were performed under well-watered (WW; 80% field water capacity), moderate water stress (MWS; 50% FWC) and severe water stress (SWS; 35% FWC) in pot-cultured wheat ( Triticum aestivum L.). Results In moderate and severe drought stress, water use efficiency (WUE B ) was increased by 27.9–34.3% in PGPR and 20-22.1% in AMF treatments, respectively, and grain yield was improved by 20.03–30.77% in PGPR and 12.13–34.34% in AMF treatments, respectively, compared with CK. Importantly, the co-inoculation of AMF and PGPR significantly promoted WUE B by 57.46–98.49% and grain yield by 131.82–94.94% compared to the average value of two sole inoculations in MWS and SWS treatments, respectively. Biomass production followed a similar trend as yield. Particularly, the above parameters were significantly enhanced with the prolonged developmental stages ( p < 0.05). ACC deaminase significantly reduced ACC accumulation in MWS and SWS, enhanced AMF root colonization, and promoted rhizosphere microbial biomass carbon and nitrogen levels across all three developing stages. Furthermore, AMF-PGPR co-inoculation enhanced chlorophyll and carotenoid contents during anthesis while reducing them during pre-harvesting. Enhanced water uptake and root activities upsurged photosynthetic attributes throughout the growing season. Conclusion AMF-PGPR co-inoculation acted as a promising solution to cope with the droughted environment via root activities for stronger water capture.