The role of a microbial consortium on gas exchange and water relations in Allium cepa L. under water and nutritional deficit conditions.

Synergistic studies of microorganisms in the last decade have been mostly directed towards their biofertilizing effects on growth and crop yield. Our research examines the role of a microbial consortium (MC) on physiological responses of Allium cepa hybrid F1 2000 under water and nutritional deficit in a semi-arid environment. An onion crop was established with normal irrigation (NIr) (100% ETc) and water deficit (WD) (67% ETc) and different fertilization treatments (MC with 0%, 50% and 100% NPK). Gas exchange (Stomatal conductance (Gs), transpiration (E) and CO assimilation rates (A)) and leaf water status were evaluated throughout its growth cycle. The MC + 50% NPK treatment with NIr maintained similar A rates to the production control. A. cepa decreased Gs by approximately 50% in the WD treatment. The highest water use efficiency (WUE) and an increase in the modulus of elasticity in response to water stress were obtained for the 100% NPK treatment under non-inoculated WD. The onion hybrid F1 2000 was tolerant to water stress and under non-limiting nutrient conditions, irrigation may be reduced. The MC facilitated the availability of nutrients under NIr allowing a 50% reduction in the application of high doses of fertilization without affecting yield, resulting in a suitable agroecological strategy for this crop.