The effect of chitosan, arbuscular mycorrhizal fungi, and compost applied individually or in combination on growth, nutrient uptake, and stem anatomy of tomato

•Application of bio-fertilizers (chitosan + compost + AMF) increased tomato growth.•Adjusting soil with bio-fertilizers reduced nutrient deficiency stress.•Bio-fertilizers application improved xylem vessels that raised nutrients transport. This study investigated the effect of chitosan and a complex of arbuscular mycorrhizal fungi (AMF) on tomato plant (Solanum lycopersicum) grown in soil with four doses of compost (C0%, C5%, C10%, and C20%). Scanning electron microscopy with energy dispersive x-ray analysis revealed the interaction of NH2 groups of chitosan with compost nitrogen that was increased by 80% after 24 h of cross-linking. Growth and physiological parameters (root length, fresh and dry biomass of shoot and root, leaf area and Fv/Fm) and biochemical parameters (sugar and protein content) were improved in mycorrhizal plants grown in soil amended with chitosan and 10% of compost (Ch+C10%M+) compared to control plants (ControlC0%M−). This improvement was correlated with the increase of the diameter and the number of xylem vessels of tomato stems. In addition, the application of chitosan and AMF together on plants grown in a poor soil of mineral elements (Ch+C0%M+), increases the stem cortex that is involved in the distribution of minerals. Chitosan application with AMF and 10% of compost was found to be the best treatment for tomato growth. Therefore, adjusting soil with these three bio-fertilizers could be an interesting agricultural tool to help plants adapt in poor soil.