PHYSIOLOGY OF SEEDS OF Ekebergia capensis (Sparmm) DRIED TO VARIED MOISTURE CONTENTS AND STORED AT SELECTED TEMPERATURE REGIMES

Abstract

Ekebergia capensis is a popular indigenous multipurpose tree species valued for alternative medicine, furniture, light construction, poles and tool handles. Production of seedlings of this tree is through seeds. There are challenges acquiring viable and vigorous E. capensis seeds for raising planting materials due to difficulties in post-harvest storage. In spite of the tree’s exceptional multipurpose qualities, very little effort has been put in improving the post-harvest storage of the seeds. Changes occurring in seeds during aging are significant as far as seed quality and longevity are concerned and are a consequence of the effects of different storage conditions and E. capensis seeds are not exceptional. In addition, information on the seed’s viability and vigour loss in storage is scanty and unreliable. It is against this background that this study investigated the effects of drying to different moisture contents (MC) and storage temperature regimes on viability and vigour loss of E. capensis seeds for a varied period of time. This was achieved by determining the rate of loss of viability, vigour and longevity of seeds of E. capensis under varying moisture contents and temperatures regimes. The experiment comprised three moisture contents (MC) (15%, 25% and 35%) and three storage temperature regimes: (-5 o C, 10 o C and 25 o C) for a period of 30, 60 and 90 days and control with moisture content of 47 %. The stored seeds were retrieved at an interval of 30 days for viability, vigour and longevity assessment. Data generated were subjected to analysis of variance (ANOVA), regression and correlation analyses using GenSTAT- 16 software. Findings from the study revealed that E. capensis seeds with higher moisture content of 35% stored across the tested temperature regimes viz: -5 o C, 10 o C and 25 o C maintained significantly higher viability, vigour and highest P50 (measure of longevity in days) compared to seeds with lower moisture content (25% or 15%) stored across all temperature regimes. In addition, seeds with 35% MC stored at 10 o C maintained highest longevity (P50) as storage period progressed to 90 days. There was a negative correlation between storage period and seed viability regardless of the storage temperatures and moisture content. Decrease in seed viability, vigour and longevity, in storage was in the order of 15%>25%>35% MC. The findings of this study showed that the critical % moisture content and storage temperature for maintenance of seed viability for a period of 30 days in seeds of E. capensis seeds is at 35% and 10 o C respectively. It is therefore recommended that E. capensis seeds should be dried up to a moisture content of 35% with storage temperature of 10 o C for 30 days for better longevity, vigour and viability.