Positive effect of warm water and acid scarification on seed germination of Canarium schweinfurthii Engl is diminished by sand substrate

Abstract

Canarium schweinfurthii is a multipurpose tree of the Burseraceae family whose population has declined tremendously in the Western Cameroon Highlands. The situation is exacerbated by a poor germination behaviour, making propagation a valuable alternative for supply of regeneration material. This study examined the combined effect of pre-sowing treatments and substrates on germination and root development of the species. Treatments were comprised of three substrates (soil, sawdust, sand) and five pre-sowing treatments (control, warm water, acid, dry heat at 100^o C, dry heat at 60^o C). Sand significantly reduced Final Germination Percentage (FGP) while it increased Mean Germination Time (MGT). Germination Rate Index (GRI) declined from soil to sand and sawdust which did not differ from each other for this trait. Root length and number of roots were highest while the latter was lowest in soil. As for the pre-sowing treatments, values of FGP and MGT were highest in warm water and lowest in the dry heat treatments in which germination was almost completely absent. No other parameter was significantly affected by pre-sowing treatment. There were significant 2-factor interactions for FGP and MGT. Although sand attenuated the effects of all three non-dry heat treatments on FGP, the margin was highest in warm water. On the other hand, the increase in MGT by sand was limited to the control and acid-treated seeds. The results suggest that sand may not be a suitable germination medium for pre-treated seeds of C. schweinfurthii while early post-germination root development of the species may be favoured by sawdust.