Use of Plant Growth Promoting Rhizobacteria in Combination with Chitosan on Maize Crop: Promising Prospects for Sustainable, Environmentally Friendly Agriculture and against Abiotic Stress

Faced with the problems posed by the abusive use of chemical fertilizers and pesticides, it is important to find other alternatives that can guarantee a sustainable and environmentally friendly agriculture. The objective of this study was to evaluate the tolerance of a PGPR (plant growth promoting rhizobacteria) Pseudomonas putida strain to different abiotic stress in in vitro conditions and the synergistic effect of this rhizobacterium in combination with chitosan extracted from crab exoskeletons on the growth of maize in greenhouse conditions. The strain of P. putida was put in culture at different temperatures, pH, and NaCl concentrations to determine its growth. Then, this strain in combination with chitosan extracts were tested for their ability to improve maize growth for 30 days. The results showed that the P. putida strain showed excellent resistance capacities to different salt concentrations, pH, and temperature variations. Moreover, an improvement in plant growth and biomass yield parameters was observed. The highest values of height, diameter, and leaf area were obtained with the plants treated with the combination of chitosan extracted from Cardisoma armatum and P. putida, with increases of 26.8%, 31%, and 55.7%, respectively, compared to the control. This study shows the possibility of using chitosan and rhizobacteria as biostimulants to improve productivity and increase maize yield in a sustainable manner.