Seaweed extract application and arbuscular mycorrhizal fungal inoculation: a tool for promoting growth and development of date palm (Phoenix dactylifera L.) cv «Boufgous»

Abstract In oases ecosystems, date palm (Phoenix dactylifera L.) is a plant that has several socio-economic and environmental roles. During the last decades, the cultivation of date palm and its development are threatened by several constraints, in particular, organic and mineral matter depletion. The main objective of this study was to evaluate the effects of a seaweed extract (SWE) derived from the brown algae Fucus spiralis and an arbuscular mycorrhizal fungus (AMF) strain (Rhizophagus irregularis DAOM 197198) as well as their combination on the growth and development of the date palm (P. dactylifera L.). Growth, physiological, and histological parameters were evaluated. The results show that AMF combined with SWE induced the greatest effect. Indeed this treatment significantly increased the total dry weight, leaf area, stomatal conductance, and nitrogen (N) and phosphorus (P) levels by 27, 36, 48, 377, and 94%, respectively, compared to the control. Potassium (K) and calcium (Ca) contents were highly increased by AMF compared to other treatments. The results also show an enhancement in quantum yield of the photochemistry of PSII (Fv/Fm) by the AMF, SWE, and AMF+SWE treatments. The number of sclerenchyma fibers in AMF+SWE, SWE, and AMF treatments was increased by 681, 164 and 154% respectively, while, the number of vascular bundles was improved by 24% in the SWE treatment compared to the control. Lastly, the results indicated the positive effect of SWE or AMF and, especially, their combination as an efficient practice to improve growth and development of date palm.