A biostimulant derived from Opuntia ficus-indica residue valorisation modulates tomato ripening and quality under contrasting water regimes

The use of residual biomass from invasive plant management as a source of bioactive compounds for the formulation of plant-based biostimulants represents a promising strategy to improve fruit quality while also contributing to circular economy strategies. In this study, we evaluated the capacity of an Opuntia ficus-indica extract, obtained from the mucilage of cladode residues generated after manual removal, to modulate tomato fruit ripening and quality. Tomato plants (cv. Moneymaker) were grown under optimal or water-deficit conditions and sprayed twice with the extract (at the fruit set stage and one week later as a reinforcement). Plant physiological status, as well as fruit production, ripening and quality at harvest were assessed. Furthermore, ripening dynamics and quality of green mature fruits were evaluated during postharvest. Biostimulant application modulated fruit ripening in a water-dependent manner, accelerating it under optimal irrigation but delaying it under water deficit. Under water deficit conditions, the extract mitigated the stress-induced acceleration of fruit ripening and improved fruit hydration by up to 10%, with a concomitant increase in the TSS/TA ratio. During postharvest, fruits from treated plants showed accelerated colour development and reduced weight loss, with reductions of 14% and 28% under well-watered and water-deficit conditions, respectively. Overall, these findings show that O. ficus-indica extract derived from plant residues exerts a stage-dependent regulation of tomato ripening and improves key fruit quality traits, highlighting the potential to valorise the waste resulting from the management of invasive plants into sustainable biostimulant applications.