Effect of Plant Growth Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi (AMF) on Salt Stress Tolerance of Casuarina obesa (Miq.)

Abstract

Salinity is one of the main abiotic stresses limiting plant growth and development. However, the use of salt-tolerant plants combined with beneficial soil microorganisms could improve the effectiveness of biological methods for saline soil recovery. The aim of this study is to identify the Casuarina obesa/ Arbuscular Mycorrhizal fungi (AMF)/Plant Growth Promoting Rhizobacteria (PGPR) association that could be used in salt-land rehabilitation programs. Thus, the plants were grown under greenhouse on sandy soil, inoculated either with PGPR (Pantoea agglomerans and Bacillus sp.), or with AMF (Rhizophagus fasciculatus and Rhizophagus aggregatum) or co inoculated with PGPR and AMF and watered with a saline solution (0, 150, and 300 mM). After 4 months of cultivation, the plants were harvested and the results obtained showed that inoculation improves the survival rate, height and biomass of the plants compared to the control plants. The results also showed that inoculation increases the total amount of chlorophyll and the accumulation of plant proline at all levels of salt concentration. However, P. agglomerans and Bacillus sp. strains alone or in combination with R. fasciculatus increased plant growth. This study showed that these strains of PGPR, whether or not associated with AMF, could be biological tools to improve C. obesa performance under saline stress conditions.

Plant Growth Promoting Rhizobacteria, Arbuscular Mycorrhizal Fungi and Their Synergistic Interactions to Counteract the Negative Effects of Saline Soil on Agriculture: Key Macromolecules and Mechanisms

“…Although an increase in plant growth and grain yield was observed when PGPR and AMF are used in combination, several factors such as environmental conditions, soil quality, and the microbial strains used, contribute to variable results. For example, a 128% increase was observed in combined grain yields of finger millet and pigeon pea in intercropping conducted at the Kolli Hills site but not the Bangalore site [ 165 ]. Generally, an increase in crop yield of approximately 30–40% was observed in combined PGPR and AMF inoculation in field studies.…”

Efficacy of Biostimulants Formulated With Pseudomonas putida and Clay, Peat, Clay-Peat Binders on Maize Productivity in a Farming Environment in Southern Benin

“…PGPRs also secrete several growth phytohormones such as auxins, cytokinins, gibberellins and ethylene which improve both root growth and whole plant growth (Lugtenberg and Kamilova, 2009;Dodd et al, 2010;Wani et al, 2013). Furthermore, work carried out in Senegal by Diagne et al (2020) has also shown that inoculation with PGPR and/or Arbuscular Mycorrhizal Fungi (AMF) can improve the salinity resistance of Casuarina obesa plants by increasing their growth parameters. The use of biologically active natural products and microbial extracts could be an important means of increasing soil nutritional status, absorption and improving the efficiency of nutrient use (NPK) by plants (De Pascale et al, 2017).…”

Microbial Biostimulants as Response to Modern Agriculture Needs: Composition, Role and Application of These Innovative Products

“…Among them, the improvement of biostimulant efficiency was taken into consideration. In order to find the appropriate tools capable of exerting the most effective biostimulant activity on plants, many studies focused on the triple interaction of plants, PGPRs, and AMFs [ 98 , 99 ]. The potential beneficial effect of the combination of different types of inocula as plant biofertilizers may depend on their better stability in adverse environmental conditions [ 100 ].…”

“…An enhancement of plant biomass and yield was detected in Arizona cypress, chickpea, wheat, swamp oak, Jerusalem artichoke, and pea plants when inoculated with PGPRs and AMFs, often exhibiting better results than non-inoculated plants or plants inoculated with a single strain [ 98 , 99 , 106 , 110 , 111 , 112 ].…”