Abstract
Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are known for their beneficial effects. In recent years, more attention has been paid to their use as biofertilizers to reduce the use of chemical fertilizers causing significant damage to the environment. To have high plant yields, biofertilizers may not be able to sustain plant demands and could be used in combination with chemical fertilizers. However, the application of biofertilizers in the field such as rhizobacteria and AMF are understudied and powerfully needed. In this context, this study aims to evaluate the effect of inoculation with rhizobacteria and AMF and their potential to stimulate two of the most economically important crops in Mediterranean semi-arid areas (Vicia faba L. and Triticum durum L.). The effect of inoculation was studied in field experiment with six treatments: (i) the control without inoculation (C), (ii) PGPR alone (PG), (iii) rhizobia alone (R), (iv) the mixture of PGPR and rhizobia (PR), (v) AMF alone (M), and (vi) the mixture of PGPR, rhizobia and AMF (PRM). The inoculation with the consortium of PGPR-rhizobia-AMF (PRM) induced the greatest effect. This inoculation improved the growth parameters (dry weight of shoots and roots) of faba bean and wheat. An improvement of 130, 200, and 78% was observed in V. faba shoot and root dry weight, and the number of leaves, respectively. Similarly, shoot and root dry weight and number of leaves of T. durum were enhanced by 293, 258, and 87%, respectively. The inoculation improved the productivity of studied plants presented by the number and weight of bean pods (270 × 104 ha-1 and 30737.5 kg.ha-1) and wheat spikes (440 × 104 ha-1 and 10560 kg.ha-1). In addition, the mineral analyses showed that the inoculation with PGPR-rhizobia-mycorrhizae improved N, P, Ca, K, and Na shoots contents, as well as the contents of sugar and proteins. Finally, we revealed the positive impact of the tested biofertilizers and the interest of adoption of innovative practices improving crops productivity and soil fertility.
Highlights
MATERIALS AND METHODSThe world population has recorded considerable growth accompanied by an accentuated need for food products; this puts pressure on the agricultural sector (FAO, 2011; PRB, 2017)
Rhizobacterial strains tested were able to produce exopolysaccharides up to 176.02 mg of CR/OD600 (RhOF155) and AIA from 10.76 to 290.64 μg/ml observed for BS17 and RhOF155, respectively
In sustainable agricultural cropping systems, these characteristics can be of crucial importance since they are based on biological processes to maintain soil fertility, plant development, and productivity
Summary
MATERIALS AND METHODSThe world population has recorded considerable growth accompanied by an accentuated need for food products; this puts pressure on the agricultural sector (FAO, 2011; PRB, 2017). One of the ways of optimizing the use of fertilizers and plant production (maintenance of nutrients and reduction of losses) would be to valorize certain biological components of the soil, including PGPR, rhizobia, as well as the arbuscular mycorrhizal fungi (AMF) These microorganisms can directly facilitate plant growth and promote plant health by helping to acquire nutrients (nitrogen, phosphorus, and essential minerals) and/or modulating root growth and architecture through the release of plant phytohormones The elongation of extra-radical mycelium increases the contact surface between minerals of the soil and plant roots They can explore inaccessible areas for the plant to collect water and nutrients and transfer them to the host plant allowing an improved growth, yield, and quality of crop production (Barea et al, 2017). More studies elucidating the effect of these microorganisms are strongly needed because they are difficult to monitor in the field (Hart et al, 2017; Ryan and Graham, 2018)
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