Amino acid biostimulant and arbuscular mycorrhizal fungi effects on chamomile productivity and soil biological properties

In semi-arid environments, the combination of naturally poor soil fertility and environmental concerns from heavy reliance on synthetic fertilizers represents a significant constraint on sustainable cultivation of medicinal species, including chamomile (Matricaria chamomilla L.). Over two growing seasons, a field trial evaluated the separate and combined effects of a plant-based amino acid biostimulant (Aminol Forte at 0, 2, 3, and 4 mL L−1) and inoculation with selected arbuscular mycorrhizal fungi (Funneliformis mosseae, F. etunicatum, Rhizophagus irregularis, and non-inoculated control) on growth parameters, productivity, nutrient absorption, and soil biological indicators in chamomile cv. Shiraz. The experimental layout followed a factorial randomized complete block design with four replications. Superior outcomes were achieved with the joint application of 4 mL L−1 Aminol Forte and F. mosseae, and the highest biological yield (8540 kg ha−1, +122% over control). This treatment also yielded the greatest flower dry biomass and efficient nutrient uptake (291.9 kg ha−1 N and 34.5 kg ha−1 P) while maintaining 72.5% relative water content. Furthermore, soil biological functions improved substantially, with microbial biomass carbon, acid phosphatase activity, and dehydrogenase activity increasing by 82%, 97%, and 136%, respectively, over the control. These results demonstrate that the combined use of amino acid biostimulants and well-performing AMF strains, notably F. mosseae, can enhance chamomile production, nutrient acquisition, and selected soil biological properties under semi-arid field conditions.