Cashew Gum (Anacardium occidentale) Hydrogel for Sustainable Irrigation of Cactus Pear: Effects on Growth, Chemical Composition, and Mineral Content

Hydrogels are substances designed to retain significant quantities of water and slowly release it to support plant growth. This study produced and evaluated the use of a test hydrogel (TH), a natural polymer derived from cashew gum (Anacardium occidentale), on the growth, chemical composition, and mineral content of cactus pear genotypes. The TH was compared to a negative control (no hydrogel; NH), and to a positive control or commercial hydrogel (CH). The CH was a synthetic polyacrylamide-based hydrogel. The study was carried out in a completely randomized design with a 3 × 3 factorial arrangement (n = 36), involving three hydrogel types × three cactus pear genotypes [Elephant Ear (Opuntia stricta); Giant (Opuntia ficus-indica); and Sweet (Nopalea cochenillifera)]. There was a significant effect of interaction (p ≤ 0.05) between genotypes and hydrogel types on cladode area, plant height, dry biomass of cladodes, and macro- and micromineral content. The use of TH promoted greater growth and improved chemical and mineral composition (p ≤ 0.05) to cactus genotypes. The Sweet genotype hydrated with TH presented the highest crude protein accumulation (p ≤ 0.05). Cashew gum-based hydrogel improved both growth and chemical composition of the cactus genotypes, and it is an eco-friendly alternative to synthetic polymers.