Germination responses of Cola acuminata (Pal. De Beauv.) seeds to different substrates, photoperiods and dehydration

Cola acuminata (Pal. De Beauv.), one of the many forest tree species which are of socio-economic importance in Western and Central Africa, is still exploited in the wild by subsistence farmers because it has not been domesticated yet. As a contribution to its domestication, the present study aimed at determining germination requirements and desiccation tolerance of seeds. Three substrates (forest topsoil, river sand and mixture of forest top soil and river sand), two photoperiods (12 hours/day and continuous darkness) and dehydration were investigated for their effects on seeds germination percentage. To evaluate the seeds’ tolerance to desiccation, fresh seeds were dried at laboratory temperature for 16 days during which seeds moisture content, seeds germination percentage and electrical conductivity of seeds leachate were monitored at two-day intervals. Results showed that the mean germination percentage recorded on the mixture of forest top soil and river sand (97.2 ± 1.0%) was significantly higher than that recorded on forest topsoil (85.5 ± 4.0%), which was in turn higher than that obtained on river sand (70 ± 1.5%). The effect of photoperiod on germination percentage was not significant (p = 0.112). As response to seeds drying, the mean germination percentage slightly decreased as moisture got lost, then drastically dropped when moisture content was below 45.95 ± 4.2%. Seeds failed to germinate when their moisture content fell below 27.1 ± 2.1%. Electrical conductivity of seed leachate exhibited a highly significant negative correlation with both germination percentage (p ˂ 0.01, r = -0.926) and moisture content (p ˂ 0.01, r = -0.931). It is concluded that the best substrate for C. acuminata seeds’ germination is the mixture of forest top soil and river sand in a 1/1 (v/v) ratio. Cola acuminata seeds are desiccation-sensitive and their storage behavior is recalcitrant. This is a significant constraint for conservation that should be addressed in further researches.Keywords: Cola acuminate, seed germination, photoperiod, desiccation tolerance, moisture content, storage behavior

Germination of

 Introduction. Despite its socio-economic importance, cultivation of Garcinia kola Heckel is very limited due to poor seed germination. The literature gives contradictory information concerning this fact. Our study therefore aimed at (1) evaluating the variability in germination traits among seeds collected from different areas of Cameroon; and (2) testing the efficiency of some hormone treatments in improving the seed germination rate, which would promote cultivation of G. kola by rural farmers. Materials and methods. Six collections of seeds originating from six locations in Cameroon were subjected to pre-sowing treatments; soaking for 3 days at room temperature in cool distilled water (control), or in cool distilled water supplemented with either 10-4 M gibberellic acid (GA3), 10-4 M naphthalene acetic acid (NAA), 10-4 M 2,4-dichlorophenoxyacetic acid (2,4-D), 10-4 M benzylaminopurine (BAP) or 10-4 M kinetin; they were then placed to germinate in laboratory conditions. Cumulative seed germination data were recorded for 30 weeks. Results. The pre-germination treatments had profound effects on the phenology of G. kola seed germination. Multiple shoots, multiple roots and callus formation were induced from seeds soaked in BAP, NAA and 2,4-D solutions, respectively. Analysis of variance showed a significant effect (p < 0.01) of seed collection on the germination velocity. Although the rate of germination was higher and the complete dormancy period lower in seeds treated with NAA than in seeds with other treatments, none of these seed treatments significantly enhanced germination. Conclusion. Variations in phenology responses of G. kola seeds to hormone treatments indicate that the tissues of this plant may be responsive in in vitro culture. Variations in seed germination velocity among collections may explain the current controversy over G. kola seed germination, and could help in further selection and domestication processes of this species

Perceptions paysannes sur les services écosystémiques d’approvisionnement, la vulnérabilité et les stratégies de conservation de Diospyros mespiliformis Hochst en zone soudanienne du Tchad

Diospyros mespiliformis Hochst. est une espèce d’arbre à usage multiple des forêts tropicales sèches qui est encore exploitée à l’état sauvage et dont les pratiques sylviculturales ne sont pas documentées. La présente étude avait pour but d’appréhender les perceptions paysannes sur l’importance socio-économique, le niveau de vulnérabilité et la pratique de la culture de cette espèce dans la zone soudanienne du Tchad. L’approche méthodologique a consisté en des enquêtes réalisées auprès de 350 personnes réparties dans 10 villages, ainsi que des observations de terrain. Les résultats ont montré que D. mespiliformis est bien connu des populations locales (100 % des enquêtés) qui en font usage dans six catégories d’usage, avec un large consensus au niveau des utilisations médicinales (Cs = 0,96), alimentaires (Cs = 0,33), dans les constructions (Cs = 0,26) et comme bois d’énergie (Cs = 0,24). Par contre le consensus est resté faible pour l’utilisation dans l’artisanat (Cs = - 0,76) et comme bois d’œuvre (Cs = - 0,83). Selon 80,2 % des répondants, les revenus tirés de l’exploitation de cette ressource contribuent significativement à l’amélioration du bien-être des ménages. En dehors de la cueillette et du ramassage des fruits, toutes les autres méthodes de récolte citées par les répondants (écorçage, prélèvement des racines, effeuillage et abatage) sont destructives, mais seulement 17,7 % des répondants en sont conscients. Une tendance régressive de la dynamique du peuplement de l’espèce est perçue par la majorité (52 %) des répondants. Selon 83,5 % des enquêtés, les habitudes en matière de culture de cette espèce sont rares voire inexistantes, à cause des difficultés de germination des graines, de la rareté des graines et des conditions climatiques défavorables à la réussite du drageonnage. Les répondants dans la quasi-totalité (99 %) se sont déclarés prêts à adopter la pratique de la culture de la plante si les contraintes de régénération sont levées. Les résultats de cette étude indiquent clairement que D. mespiliformis serait une espèce propice à la domestication participative pour l’intensification du système agroforestier dans la zone soudanienne du Tchad. &nbsp; Diospyros mespiliformis Hochst. is a multipurpose tree species from tropical dry forests that is still exploited in the wild and whose silvicultural practices are not documented. The aim of this study was to understand the peasants’ perceptions on the socio-economic importance, the level of vulnerability and the cultivation practice of this species in the Sudanese zone of Chad. The methodological approach consisted of surveys carried out among 350 people in 10 villages, as well as field observations. The results showed that D. mespiliformis is well known to local populations (100% of respondents) who use it in six categories of use, with a broad consensus for use in medicine (Cs = 0.96), food (Cs = 0.33), constructions (Cs = 0.26) and as fuelwood (Cs = 0.24). On the other hand, the consensus remained weak for use in crafts (Cs = - 0.76) and as lumber (Cs = - 0.83). According to 80.2 % of respondents, income from the exploitation of this resource significantly contributes to improving household well-being. Apart from picking and collecting fruit, all other harvesting methods cited by respondents (debarking, root picking, leaf stripping and felling) are destructive, but only 17.7 % of respondents are aware of this. A regressive trend in the population dynamics of the species is perceived by the majority (52 %) of respondents. According to 83.5 % of respondents, the cultivation habits of this species are rare or even non-existent, because of poor seed germination, the scarcity of seeds and climatic conditions unfavorable to the success of suckering. Almost all respondents (99 %) declared themselves ready to adopt the practice of growing the plant if the regeneration constraints are lifted. The results of this study clearly indicate that D. mespiliformis would be an interesting species for participatory domestication for the intensification of the agro-forestry system in the Sudanese zone of Chad