Biowaste-derived pectin–lignin hydrogels as controlled-release biostimulant carriers for enhanced drought tolerance

Sustainable strategies are urgently needed to enhance crop performance while reducing environmental impacts from conventional fertilizers. Humic acid is an effective biostimulant, but rapid leaching limits its utility. In this study, pectin-lignin biohydrogels derived from biowaste were developed to deliver humic acid efficiently and improve soil water retention. The physically crosslinked hydrogels exhibit 42% porosity, 600% swelling, strong mechanical stability, and biodegrade in soil within two months. Humic acid release is pH-responsive, with faster release under neutral and alkaline conditions. Experiments conducted using rapessed plants under water-deficit conditions with rapeseed, clearly indicate the use of hydrogels led an increase of the plants water content, up to 87%, and a reduction of TBARS, anthocyanin and proline content, which indicate the response of the plant to the stress. The use of hydrogel application partially restored plant water status, reduced biomass loss, and enhanced soil moisture retention. These findings highlight the synergistic effects of controlled biostimulant delivery and improved water-holding capacity. This work establishes pectin-lignin hydrogels as a sustainable, multifunctional platform for enhancing crop resilience and mitigating drought stress.