Superabsorbent Polymer Coating on Seeds: A Review

Abstract

The growing impacts of climate change such as unpredictable weather patterns, prolonged droughts, and extreme heatwaves pose serious threats to global agriculture by reducing crop productivity and endangering farmers’ livelihoods. In regions like India, where drought stress is frequent, there is an urgent need for climate-resilient agricultural practices. One promising solution is the use of Superabsorbent Polymers (SAPs) in seed coatings. These hydrophilic materials can absorb and retain large amounts of water, creating a moisture-rich micro-environment that supports seed germination and early seedling development under water-limited conditions. SAPs function through osmotic pressure and are available in fossil-based and bio-based, degradable and non-degradable forms. Bio-based SAPs are becoming increasingly popular due to their distinct focus on the environmental impacts of fossil versus bio-based alternatives, while also supporting the evaluation of seed coating methods aimed at promoting sustainable agricultural intensification. Various SAP formulations such as cross-linked polyacrylamide and starch-graft polymers have shown positive effects on crops like maize, cotton, red clover, and others, enhancing water-use efficiency, nutrient uptake, and drought tolerance. Despite their benefits, challenges remain, including high costs, limited biodegradability of synthetic SAPs, and reduced performance in extreme soil and climate conditions. This review synthesizes findings from recent experimental and field studies conducted in the past few years, highlighting the need for continued research to develop cost-effective, biodegradable SAP alternatives and assess their long-term performance in field conditions to support sustainable agriculture.