Abstract

Seed storage operations in the tropics would benefit from low input techniques that can maintain seed physiological quality for considerably long periods without investments in cooling. A study was conducted to evaluate seed vigour and estimate seed longevity in maize during dry storage with commercial desiccant (silica gel) at various levels of gel/seed ratios in air-tight containers under ambient tropical temperature. Seed moisture content (MC) was lowest indicating effective drying at 1:1 gel/seed (100 g of seed stored over 100 g of gel) and 1:2.5 gel/seed ratio (100 g of seed stored over 80 g of gel) during 2 trials set up in 2005 and 2006. After 4 months of storage, laboratory seed germination capacity and vigour variables were consistently higher (p<0.05) in seed lots stored at 1:1 and 1:2.5 gel/seed ratios than seed lots stored at 1:20, 1:10 and 0:1 gel/seed ratios in the 2 trials. Probit analysis of seed survival data from controlled deterioration (CD) tests showed that estimates of potential longevity were optimal at 1:2.5 gel/seed ratios in the two experiments. The results indicated the possibility of maintaining seed physiological quality in containerized-dry storage under ambient humid tropical storage conditions. Moreover, the storage system experimented in the study simulated a condition that eliminates labour involved in regenerating or drying silica gel, since silica gel was not changed throughout the storage period. Gel/seed ratios between 1:1 and 1:2.5 are recommended for direct application or in developing technology and equipment for containerized-dry seed storage in the humid tropics.

Key words: Maize, low input storage, silica gel, seed quality, potential longevity.