Storage conditions of yeheb (Cordeauxia edulis Hemsl.) seeds :

Abstract: Yeheb, Cordeauxia edulis Hemsl., is an endemic, semi-arid shrub which has become over utilised and is today in danger of extinction. Its natural regeneration is severely threatened since it is used as seasonal feed for animals like camels and goats, fire wood and food for humans. To learn more about the shrub's biology and manage the regeneration of the shrub by seed propagation a SIDA financed collaboration project between the Swedish University of Agricultural Science, Ultuna and the Alemaya University in Ethiopia was initiated in 2002. Seeds can be divided into three categories, depending upon their length of life, responses to desiccation and preferred storage temperatures. Orthodox seeds are best stored in low temperature and with low moisture content, recalcitrant ones are sensitive to both desiccation and often low temperatures while intermediate seeds represent something in between the former two categories. The length of time for which a seed can survive is genetically programmed but there are several factors that determine whether the seed will survive for this period of time or if it will die at an earlier point. Finding the optimal storage conditions for yeheb seeds is of great importance since the seeds age and deteriorate quite fast and the ultimate objective is to manage the survival of seeds between two rainy seasons. The aim of this study was to find the best storage conditions for the seeds of yeheb. This was done in experiments by variating temperature (6±1 respective 16±3°C) and moisture content (in equilibrium with H2SO4 in concentration 25, 30, 35, 40, 45 and 50 % respectively). The germinability was then evaluated by germination tests after 4 and 6 months respectively. The experimental results showed that it was possible to store seeds while maintaining satisfactory germinability. There were significant differences in germinability between different water contents, as between the both storage temperatures. No significant differences could be observed between 4 and 6 months of storage but a small but still significant reduction in germinability was detected in comparison with fresh seeds. The best results were obtained in 16°C and with a moisture content of 10.2 och 12.3 %, equal to H2SO4 concentration 45 and 40 %, where the germinability reached 93.8 %. The experimental results indicated that seeds from the yeheb shrub could be classified as intermediate.