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Table 2 shows germination ratesusing different storage technologies.Studies on rice seeds in Bangladeshand Cambodia (100–398 days), onmaize seed in Mexico, Thailand, andBangladesh (90–280 days), and onbarley and wheat in Cyprus and Israel(120–900 days) showed hermeticstorage seed germination of 81–95%after 90 days. 1,2 Another study fromVietnam on peanut seeds showed98% germination after 8 monthsversus 4% when stored unprotected. 3It is also important to recallthat hybrid seeds not only are moreexpensive than conventional farmergrownseeds but also are moredelicate and prone to damage. Acontinuing shift to high-yield hybridseeds makes effective storage allthe more crucial, since without highgermination rates and maintenanceof vigor, these“high-value” seedshave no value to the farmer. ThePBPRE–PhilRice study showed thatby month 6 of storage, hermeticmethods are economically favorableto the other 3 methods (Table 3).Table 2. Mean % germination rate of Mestizo 1 hybrid paddy(unmilled) seeds stored using different storage technologies.Storage time after harvest (months)Storage method 0 3 6 9Hermetic 96.2 96.5 93.3 86.2Cold room 96.8 97.6 93.0 89.6Air-conditioned 94.3 94.8 88.1 85.8Control (unprotected) 92.9 92.9 76.4 74.7Source for Tables 2 and 3: Savio GC. Preservation of Mestizo Rice (PSB Rc72H) usinghermetic and low temperature storage techniques, presented at the Internationalworking Conference on Stored Products Protection (IWCSPP), São Paulo, Brazil. p 3.Conventional storage was foundadequate only up to 3 months.Effective hermetic storagerequires reasonably priced hermeticcontainers, now possible withmodern specialized materials.Most widely used at the momentis the SuperGrainbag liner, a60-kg-capacity, 0.078-mm-thickco-extruded plastic composed ofpolyethylene protective layers onthe outside and a proprietary gasbarrier in the middle (photo, oppositeleft). This plastic has extremely lowpermeability to water vapor andoxygen (typically 8 grams per squaremeter per 24 hours for water vaporand as low as 3 cubic cm per squaremeter per 24 hours for oxygen).Cocoon is another form ofhermetic storage (photo, oppositecenter). It is made from a specialgrade of 0.83-mm polyvinylchloride(PVC) with a permeability to oxygenof 55 cubic centimeters per squaremeter per 24 hours and to watervapor of 8 grams per square meterper 24 hours. Available in capacitiesof 5 to 1,000 tons, theCocoon protects seedsin jute or polypropylenebags during storage.The TransSafelineroffers hermetic storagefor seeds during transport(photo, opposite right).It acts as a hermetic linerfor standard 20-feet- or40-feet-long shippingcontainers, allowingTable 3. Cost comparison (Philippines) using four storage methods for preserving Mestizo 1 hybridpaddy seeds (all values in US dollars; $1 = 50 Philippine pesos).Costs Control Hermetic3 months’ storage 6 months’ storageColdroomAir-con Control HermeticColdroomAir-conInvestment 82,250 1,744 12,820 16,230 82,250 1,744 12,820 16,230Operating24,991 504 3,548 3,820 31,086 504 4,196 3,950expensesPer 20-kg bag 2.50 2.52 3.55 2.55 3.11 2.52 4.20 2.63Investment and operating expenses based on: control 10,000 bags; hermetic 200 bags; cold room 1,000 bags; air-conditioned 1,500 bags.safe intercontinental transport.Through the efforts ofIRRI and its national partners,hermetic rice seed storage isnow being used successfully inBangladesh, Cambodia, India,Indonesia, Laos, Myanmar, thePhilippines, and Thailand.Hermetic storage of paddy(unmilled) and milled rice is alsogaining popularity. IRRI reportsthat grain quality, as measuredby head rice yield and the numberof broken kernels, is higher forhermetically stored paddy ricethan for traditionally stored rice.In Cambodia, head rice yields forhermetically stored grain were 10%higher than for traditional openstorage over 12-months period.(Head rice yields are the percentageof head rice—whole grains andbroken kernels that are at least75–80% whole—obtained frompaddy after milling.) In Vietnam in2003, hermetic storage resulted ina 4.5% reduction in the number ofbroken kernels after 6 months.The current revival of hermeticstorage, using high-performanceplastics, has made possible relativelyinexpensive storage of rice seeds,paddy, milled rice, brown rice,maize, wheat, and pulses for bothhuman and animal consumption.As the benefits of hermetic storagebecome more widely known, useof the technology is likely to growthroughout Asia and beyond.Sometimes it takes a few thousandyears for a good idea to take hold.Dr. Villers is president of U.S.-based postharvest technologycompany GrainPro, Inc. Mr.Gummert is a postharvest expertat IRRI.The use of commercialproduct or company namesin this article does not implyendorsement by IRRI.1DeBruin T. 2005. Innovations in seed storage methods. Published in Asian seed and planting material. Philippines, January.2Villers P, De Bruin T, Navarro S. 2004 Advances in hermetic storage as a methyl bromide replacement. 4th CAF Conference, Brisbane, Australia, February.3Villers P, De Bruin T, Navarro S. 2006. Development and applications of the hermetic storage technology. Published in Proceedings of the 9thInternational Working Conference on Stored Products Protections (IWCSPP), São Paulo, Brazil, October.Rice Today January-March 200937