Abstract
BACKGROUND: Bio-stimulants are natural substances that have achieved considerable advances. However, they remain inconsistent under biotic and abiotic stress, limiting their utilization in sustainable agriculture. There is an urgent need for cost-effective and multifaceted approaches to phytopathogens control, integrating bio-stimulants that enhance plant resistance and improve the biomarker of potato tuber quality. This study evaluated the efficacy of compost, macroalgae, Trichoderma harzianum, and arbuscular mycorrhizal (AM) fungi as bio-stimulants and their combinations in managing the black scurf disease of potato plants that causes serious yield losses. RESULTS: The findings indicated that all assessed bio-stimulants markedly reduced the disease severity compared to the untreated control group. Notably, both T. harzianum and macroalgae demonstrated higher effectiveness when applied individually than other individual treatments, which achieved a reduction of DS by 71.57%, 69.61%, respectively, and DI by 71.43%, 64.28%, respectively. However, combinations of AM fungi (My) with macroalgae (Al), which achieved the highest reduction of DS by 83.46%, and DI (78.6%) in compared with the infested control. While the triple mixture of AM fungi, T. harzianum, and macroalgae exhibited superior efficacy in reducing disease incidence by 82.14% when compared to the infested control. Furthermore, all bio-stimulant treatments contributed positively to plant growth and tuber yield, particularly those involving AM fungi combined with macroalgae or their individual applications. The highest quality tubers of potato starch and -amylase content resulted from treatments with macroalgae alone or combined with mycorrhizal fungi. These tubers demonstrated improved tolerance to elevated temperatures at 60 °C in an oven until completely dry, with significant variations in potato quality correlating particularly with their starch and α-amylase contents. Furthermore, the influence of bio-stimulants on Indole-3-acetic acid, an important growth hormone, was consistent with observations obtained from greenhouse experiments. CONCLUSIONS: These findings highlight the potential of biologically-based strategies for managing black scurf in organic potato cultivation. Bio-stimulants, especially mycorrhizae and macroalgae, offer a sustainable approach to enhancing plant health, suppressing disease, and improving tuber quality.