Distribution, characterization and propagation methods for conservation and utilization of oyster nuts telfairia pedata in Tanzania

Abstract

Oyster nut (Telfairia pedata) is a native East African climber, growing naturally or planted in association with tall trees Tanzania (including Zanzibar island), Kenya and Uganda. Plot less sampling method within different land use (farmlands, homesteads, and along riverbanks) was used to understand the spatial distribution of oyster nuts across elevation and rainfall gradients and a cross-sectional survey using semi-structured questionnaire was conducted on 346 respondents to assess the utilization and conservation status of oyster nuts in northern Tanzania. In addition, phylogenetic analysis were used to assess the genetic variability of oyster nuts collected from the study location and lastly developing local propagation methods for the production of oyster nut seedlings for farmers in northern Tanzania. The findings on the spatial distribution of oyster nuts indicated that more oyster nut plants grow in higher elevations and areas with higher rainfall. The findings on utilization and conservation status of the oyster nuts reveal that about 21% of respondents used oyster nuts for cooking with other staple foods while (18%) claimed that the nuts are used by pregnant and lactating mothers for medicinal and breast milk stimulation and nine percent indicated that the nuts are used for ritual and cultural devotions. Also, respondents within the 36-50 age groups reported the greatest diversity of uses of oyster nuts were (51%) compared with those aged below 36 years old (21%). The findings on genetic analysis suggest that the oyster nut (Telfairia pedata) is the only specie that exists in Tanzania with similarity of >99% to known accessions as deposited in the National Center for Biotechnology Information (NCBI). Although the accessions were obtained from different districts in Northern Tanzania, their close genetic similarity indicates that they might have originated from the same parents and were introduced to other sites through cultivation by human interventions. The findings on propagation methods for the production of oyster nut seedlings indicate that mother plant topsoil and Nitrogen, Phosphorus and Potassium fertilizer levels and mother plant topsoil and cow manure are the best media for the propagation of oyster nuts using stem cuttings. The study concludes that oyster nuts offers multiple benefits to farmers and is the only species that exist in Tanzania. The study recommends: (i) Promote the multipurpose and only oyster nut plant that exist in Tanzania through workshops and seminars to contribute to food security and biodiversity conservation; (ii) mother plant topsoil and NPK or cow manure are the most suitable soil mixture for raising oyster nuts from stem cuttings; and (iii) Research institutions can take an interest in both in-situ and ex-situ long-term monitoring trends of oyster nuts (Telfairia pedata) distribution as it is the only specie that exists in the country.