Applications of dry chain technology to maintain high seed viability in tropical climates

Seed storage life in tropical areas is shortened by high humidity and temperature and the general inaccessibility to dehumidifying and refrigeration systems, resulting in rapid decreases in seed viability in storage as well as a high incidence of fungal and insect infestations. The dry chain, based on rapid and deep drying of seeds after harvest followed by packaging in moisture-proof containers, has been proposed as an effective method to maintain seed quality during medium-term storage in humid climates, even without refrigeration. In addition, seed drying with zeolite drying beads can be more effective and economical than sun or heated-air drying under these warm, humid conditions. In this paper, we review recent published literature regarding the dry chain, considering different crop species, storage environments and seed traits. In addition, we provide new original data on the application of dry chain methods and their implementation at larger scales in South Asia, Latin America and Pacific Island Countries. The clear conclusion is that the combination of reusable drying beads and waterproof storage containers enables the implementation of the dry chain in tropical climates, enhancing seed viability and quality in storage of many crop species. The dry chain approach can therefore significantly enhance seed security for farmers in many tropical countries. Finally, we propose actions and strategies that could guide further scaling-up implementation of this technology.