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Evaluating the germination potential of Pterocarpus angolensis and Strychnos cocculoides with tissue culture techniques (Master thesis)

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Title Evaluating the germination potential of Pterocarpus angolensis and Strychnos cocculoides with tissue culture techniques (Master thesis) ?
Author Heita, Hleni Twiitileni Ndeshipanda ?
Abstract The importance of indigenous tree species to local livelihoods can never be overstated. The species provide wood materials and non-woody resources, such as fruits and traditional medicines. Pterocarpus angolensis and Strychnos cocculoides are two important tree species found in a Namibian and adjacent countries’ woodlands. Local people highly depend on the trees for wood (P. angolensis) and fruits (S. cocculoides). Due to over-exploitation of P. angolensis and S. cocculoides, the trees are on the verge of getting extinct. For instances; P. angolensis is mostly used for its ever-demanded wood products, thus become vulnerable to immense cutting down. Several attempts to propagate these two-tree species using traditional/conventional method i.e. nursery, are reported to have produced futile results. As such, there is need to explore other alternative germination methods for these trees. The current study evaluated germination potential of P. angolensis and S. cocculoides using the tissue culture germination method. The study objectives were: To compare the effect of tissue culture and nursery techniques on the germination success of P. angolensis and S. cocculoides; to develop a robust tissue culture protocol to optimise in vitro germination of P. angolensis and S. cocculoides and to evaluate the effect of different tissue culture aspects on the germination of these species. This was achieved by planting 60 seeds (30 each) of P. angolensis and S. cocculoides seed in the nursery and the performance of several in vitro tissue culture experiments under a controlled laboratory conditions. The influence of several aspects of tissue culture namely, the explant types (buds, seeds without seed coat, embryos, apical and axillary shoots); Agar media (Agar without hormone and Agar with hormones); pH (5.5 and 5.8); and surface sterilisation of explants on the germination success of P. angolensis and S. cocculoides were also investigated to identify optimal tissue culture protocol. Whereby, petri dishes with three treatments (sterilised, agar and explants) were placed randomly inside an SMC 1400 low-temperature incubator at 25°C with a 12-hour day and night photoperiod. Every third day, growth parameters such as germinated seedlings, plantlets length (roots and shoots), contamination and germination date were recorded up to 10 weeks after inoculation. The results show that germination of P. angolensis and S. cocculoides can be promoted using tissue cultures as opposed to the nursery methods. For instance, up to seven plantlets (P. angolensis and S. cocculoides) can be produced in tissue culture methods within seven days. This however, cannot be reported from the nursery counterpart which only produces two and iii | P a g e seven seedlings from P. angolensis and S. cocculoides after 30 days respectively. From the tissue culture aspects, the results have shown that only seed (explants) without the seed coat and embryos yielded sufficient results for both species. For instance, there was no significant difference (P = 0.12) for germination percentage between the two types of explants (seeds without seed coat and embryo) for P. angolensis as contrasting to S. cocculoides explants (dry and fresh embryo) were a significantly different (P = 0.0010) was obtained. There was a significant difference in germination of explants between agar medium without hormones (A) and with hormones (A+H) in both P. angolensis (P = 0.0049) and S. cocculoides (P = 0.0001), with A producing high germination in all the species. Pterocarpus angolensis seed explants yielded high germination percentage at pH 5.8 while there was no significant difference in germination success between pH of 5.5 and 5.8 in S. cocculoides explants (fresh and dry embryos). The study will be the first to demonstrate and develop a tissue culture protocol for P. angolensis and S. cocculoides of Namibia. It´s finding may contribute to the replanting of the two-tree species and eventually increase the tree stands reported depleting from the ecosystem. Therefore, the study recommends the use of tissue culture over the nursery germination method for P. angolensis and S. cocculoides. While suggesting for further investigation on aspects such as optimal temperature and light intensity required in tissue culture. Lastly, Improved germination of indigenous species has potential to contribute significantly to the conservation of these tree species which are under threat of extinction due to over-exploitation. ?
Dataset
Document Reference Date Type publication ?
Date 2017-12-01 ?
Language English ?
Online Linkage ?
Associated project SASSCAL (Phase 1) ?
Dataset Classification
Type PDF ?
Category thesis ?
Metadata
Metadata Contact Person De Cauwer, Vera, Dr ?
Metadata Date Stamp 2018-08-03 ?
Identifier
Internal identifier sdp_doc_documents_6476 (Link)