Aloe vera-based copolymer hydrogel enhances drought tolerance and water use efficiency in lettuce

Drought-induced insufficient soil moisture severely threatens crop growth and yield, making efficient water-retaining materials a feasible solution to enhance crop drought tolerance. In this study, an eco-friendly Aloe vera-g-P(AA-co-AMPS) hydrogel (AVH) was synthesized via microwave-assisted graft copolymerization, and its water retention capacity and effect on lettuce drought tolerance were investigated. Characterized by Scanning Electron Microscope (SEM）, Fourier Transform Infrared Spectroscopy （FTIR）, and Thermogravimetric Analysis （TGA）, AVH showed a three-dimensional interpenetrating network structure. It showed an equilibrium swelling ratio of 2618.4 g/g in ultrapure water (higher than reported hydrogels) and retained 95.35 % water after 163 h at 25 °C, indicating excellent swelling and long-term water retention. Pot experiments under mild (55 % field capacity) and severe (35 % field capacity) drought showed that with AVH increasing from 0 % to 0.3 %: under mild drought, lettuce leaf fresh weight and total chlorophyll increased by 405 % and 79.1 %, respectively; under severe drought, root length, root weight, and soluble sugar increased by 242 %, 360 %, and 72.2 %, respectively, while malondialdehyde decreased by 51.4 %. These results indicate that AVH can reduce plant oxidative damage, optimize osmotic regulation, and promote lettuce adaptation and growth under drought. Although further research on reusability and large-scale testing is needed, AVH shows promising application potential in crop drought control due to its excellent water absorption and retention capabilities, providing new insights for developing eco-friendly drought-resistant materials. • Aloe vera-g-P(AA-co-AMPS) hydrogel (AVH) was synthesized via graft copolymerization. • Superb water control: AVH swells 2618 g/g, retains 95 % water for 163 h, boosts soil moisture. • Enhances drought tolerance: AVH elongates roots, cuts MDA 71 %, ups sugars 35 % for resilience. • Boosts crop growth: AVH raises lettuce weight 405 %, chlorophyll 79 %, biomass 813 % at 55 % FC. • Sustainable farming aid: Biodegradable AVH combats water scarcity with low eco-impact.