Reflective Covers to Prevent Condensation in Sealed Storages in the Tropics
J.E. DONAHAYE,1* S. NAVARRO,¹ GLORY SABIO,² MIRIAM RINDNER,¹ A. AZRIELI¹ AND R. DIAS¹
¹Agricultural Research Organization, Department of Stored Products, The Volcani Center, Bet Dagan 50250, Israel
[e-mail: jondon@netvision.net.il]
²Bureau of Postharvest Research and Extension, Munoz, Philippines
Abstract: A sealed structure (the 'Volcani Cube'®) that provides protection to grain without the use of chemical pesticides was used in these experiments. A major advantage of the Volcani Cube is that it can be used to safely store grain outdoors where no suitable storage buildings are available. Under tropical conditions, when grain is stored in the open with no shade, ambient diurnal temperature fluctuations, can create temperature gradients within the stack that cause convection currents to carry moisture to the upper layers of grain. To overcome this effect, an upper insulating layer of bags containing straw or husks was employed. Under tropical climates this solution enables safe storage of maize and paddy for periods of up to 3 months; for more extended periods the top moistened layer of husks should be replaced with dry material. In a search to develop an alternative inexpensive and convenient method of insulating the stack from diurnal temperature fluctuations, the use of a shade screen placed above the cube was investigated. This material described as a knitted thermal screen is formed from aluminum coated high-density polyethylene threads. Trials conducted with Volcani Cubes in tropical and subtropical climates showed that grain is protected under sealed storage by maintaining the number of live insects below the threshold of economic damage without the need for pesticides. For dry paddy, it was shown that after 5 months storage under a reflective cover, no perceptible increase in moisture content was found at the top of the stack and the grain remained in good condition.
Key words: seed storage, sealed structures, germinatlon, insect pest, paddy, maize
