Microbial inoculants improve nutrients uptake and yield of durum wheat in calcareous soils under drought stress in the Mediterranean region

Abstract

ABSTRACT Despite some evidence in greenhouse experiments, the benefits of Bacillus subtilis and Trichoderma asperellum on nutrients uptake by plants under field conditions are unknown. This work aims to study the effect of these microbial inoculants on durum wheat nutrition and yield under Mediterranean conditions where soils may lead to micronutrients and phosphorus deficiencies and where drought may promote low use efficiencies of applied fertilizers. To this end, three experiments were performed in two growing seasons. B. subtilis increased the uptake of nitrogen, phosphorus, and manganese relative to other treatments in the experiment carried out in the first growing season involving two experimental sites. The increased phosphorus uptake was attributed to the increased activity of alkaline phosphatase. In this first season, T. asperellum increased acid phosphatase activity without effect on P uptake and decreased the P to Zn molar ratio in grains, thus improving grain quality for human consumption. In the second season, the effects of microbial inoculants were less evident possibly due to favourable environmental conditions for crops (higher water availability) or phosphate fertilization. Results evidenced that B. subtilis can be effective improving the development and nutrient uptake of durum wheat under more stressful conditions, such as drought stress.