Improved upland rice cultivars introduced in Volta Region, Ghana, have been perceived to store poorly compared to farmers' traditional cultivars. A survey was conducted in 2003 in the Hohoe district of this region, where a Participatory Varietal Selection programme had started in 1997, to gain insight into farmers' seed production and storage practices that are likely to affect seed quality in storage. Farmers rated keeping quality (p < 0.001), tolerance to storage pests (p < 0.001), seed quality (p < 0.001) and establishment of their local cultivars Kawomo, Viono and Wuwulili as much better than the improved cultivar IDSA 85. Initial seed moisture content ranged from 12.8 to 18% and germination from 0 to 82%. There was a significant relationship between seed moisture content and duration of drying prior to storage (p < 0.001) and storage method (p = 0.015). Germination loss in storage was rapid at high moisture content and slow at low moisture content. Between 60 and 80% of seeds germinated after six months storage at 12.8% moisture content. The viability equation predicted accurately germination of farmer-saved seed stored under ambient temperature in Ghana. Except for the japonica rice cultivar WAB 126-18-HB, the traditional cultivars Kawomo, Viono and Wuwulili survived better in storage than improved cultivars. There is a need to improve seed quality of improved cultivars if farmers are to benefit from their higher yields and grain quality and to improve storage practices.
SUMMARYThree upland rice species, viz. Oryza sativa, Oryza glaberrima and an O. sativa × O. glaberrima interspecific hybrid, were grown in Ghana, harvested, and field cured under open (wet) and within ventilated but rainproof containers (dry) conditions for 5 weeks. Seeds from both environments were assessed weekly for physical, physiological and pathological quality. The relationships between air temperature and relative humidity, and seed moisture content (MC) and water activity differed between curing environments but within curing environments, relationships between seed MC and water activity were comparable among species. Prolonged field curing resulted in structural damage evidenced by the formation of multiple cracks in the endosperm; these were more frequent in wet cured seeds. Diverse fungal species were isolated from wet (22 species) and dry (23 species) cured seeds with a number of soil-borne species in the wet environment. Curing environment did not influence levels of fungal infection in O. glaberrima seeds but dry curing was associated with higher levels of fungal infection in O. sativa and O. sativa × O. glaberrima. Seed germinability in all the three species was higher in the dry cured seeds although vigour was relatively lower than wet cured seeds. Field curing the seeds of these three species within a dry environment could potentially improve subsequent seed viability, aid in moisture management and minimize structural damage to the endosperm; however, research on how fungal infection could be curbed under such conditions is needed.
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