Comparative studies of drying methods on the seed quality of interspecific NERICA rice varieties (Oryza glaberrima x Oryza sativa) and their parents

Seed moisture content (MC) is a key component that determines storability of germplasm conserved in seed genebanks. The purpose of this research was to compare the efficiency of sun-, shade-, silica geland conventional room drying in terms of rice seed MC and viability using seeds of two interspecific progenies (NERICA 1 and NERICA 3) and their parents Oryza glaberrima and O. sativa varieties harvested 15 days before, at and 15 days after mass maturity. Sun drying most significantly reduced MC (4-5%) and was comparable with silica gel drying regardless of the variety tested and the maturity stage at harvest. Likewise, sun drying gave the best germination percentages followed by silica gel. Shade and room drying did not significantly lower MC and led to poor germination, especially when rice was harvested prematurely. Except for the sativa variety, harvesting prematurely resulted in no germination. In contrast, the initial germination percentages in all tested varieties improved as rice was harvested at or after mass maturity rather than 15 days earlier. Though comparable to sun drying, silica gel may not be readily available and affordable for resource-limited seed storage facilities. In this case sun drying was found an effective and affordable method for short-term storage, especially farm-saved seeds.