Browsing by Author "Washa B., Washa"

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    Assessment of African Blackwood (Dalbergia melanoxylon) Population Structure in Kilwa District, Tanzania
    (Tanzania Journal of Science, 2021-10-30) Washa B., Washa; Nyomora, Agnes; Nnungu, Stephen I
    Overharvesting and limited conservation efforts have posed a serious threat to future availability of Dalbergia melanoxylon in Tanzania in recent years. The study was conducted between 2018 and 2020 covering Mitarure Forest Reserve (MFR) and 2 surrounding community forests of Ngea and Nambawala in Kilwa District. The purpose of the study was to assess the existing population status of the species in Tanzania. A total of 36 circular plots in Mitarure and 15 plots in each community forest were laid down. Data were recorded for the number of stems per plot, and then converted on per hectare basis where the basal area and densities per hectare were calculated. Data was disaggregated into 5 Diameter at Breast Height (DBH) generated distribution classes ranging from DBH 0 to more than 45 cm. The results revealed that, there was a contrast between the Mitarure Forest Reserve and community forests in terms of individual number of trees per unit area, basal area and densities. The numbers of stems per hectare for the species were found to be 16, 10 and 8 stems/ha in Mitarure, Ngea and Nambawala forest, respectively. Dalbergia melanoxylon in Mitarure forest was normally distributed. The respective basal area was over 80 m2 per ha in Nambawala against over 60 in MFR and Ngea. The results suggest success of the communities in conserving the species after previous overharvest. Authorities should frequently visit forests to increase the population of the species and reduce unauthorised harvesting.
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    Effective Cutting type in the Rooting of Dalbergia melanoxylon in Tanzania
    (International Journal of AgriScience, 2014-04) Washa B., Washa
    A study was conducted to assess the effective type of cutting in rooting of Dalbergia melanoxylon, a woody and non-domesticated species but of highly valued wood and wide spread in tropical Africa and overharvested. Softwood, semi-hardwood, hardwood and root cuttings were excised in wet season and dry season 2010. Soil rhizosphere of the sampled plants was used as potting media in a non-mist propagator in a split plot design. Rooting test was monitored for 3 months during the two seasons. Parameters recorded during the experiment included the proportion of cuttings that rooted, callused, sprouted and the number of roots per cutting. The data were analyzed according to objectives and variables of the study using SPSS software. Results from each experiment were analyzed separately using ANOVA in SPSS software, while differences between treatment means were compared using DDuunnccaann Multiple Range Test. Results indicated 100% rooting softwood cuttings, 37% in root cuttings and none of the semi-hardwood and hardwood cuttings rooted. Softwood cuttings of less than 15gms outperformed others in rooting of D. melanoxylon followed by root cuttings. Plant propagators are advised to use softwood cuttings.
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    The First Tissue Culture in Dalbergia melanoxylon: Problems and Limitations (Book Chapter 14) of a Book Named: Current Research Trends in Biological Science. Vol. 4, 2020
    (Book Publisher International, 2020-09-14) Washa B., Washa
    The first attempt dared on Dalbergia melanoxylon tissue culture was conducted from 2010 to 2013 in the Botany Laboratory University of Dar es Salaam. A total of 500 seeds were sterilized at different concentrations of reagents and inoculated at different strengths of the Murashige and Skoog medium for germination to obtain disease-free explants for callus induction trials. A total of 400 nodal segments obtained from germinated seeds were sterilized at different concentrations of reagents and inoculated at different hormonal combinations to induce callus formation for seedling multiplication. Results from this tissue culture attempt set a foundation for tissue culture success in Dalbergia melanoxylon on the future research. Only 19.8% of seeds inoculated in half strength of Murashige and Skoog medium germinated within 7 days while only 6.8% of seeds inoculated in full strength germinated within 6 days. A total of 1% of inoculated Dalbergia melanoxylon fragments in Murashige and Skoog media supplemented with hormone combination at 2.0 mg/l BAP + 0.5 mg/l NAA developed callus after16 days from the inoculation day. The final weight of the callus at the last record was 0.62 g. The colour of callus was green and friable in nature. Other hormonal combinations in this case did not induce callus. These results suggested that the problems which affect seed germination in the natural environment are also reflected on germination in the Murashige and Skoog medium and in callus induction. Vulnerability to fungal attack is a limitation for successful callus induction and germination in the culture room. More research under improved sterile conditions is needed to improve callus percentage for seedling multiplication.
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    Recent Research Advances in Biology Vol. 5
    (Book Publisher International, 2021-02-20) Washa B., Washa
    A study was conducted in Dalbergia melanoxylon (African Blackwood) comparing the ability to form seedling between seed germination in the soil, germination in the Murashge and Skoog medium (MS) and rooting of the cuttings to form a seedling. An overharvested species D. melanoxylon have a highly valued wood but not propagated. This is why in recent years there have been some efforts to conduct investigations that can improve seedling production. About 2 kilograms of seeds were purchased from TTSA and cuttings (root, softwood, and hardwood stem cutting) were collected from the forest for an experiment in 2010 at the Botany Department University of Dar es Salaam. Three treatments were employed for soil germination (Low, Medium, and High moisture level) while two treatments were employed for MS germination (Half strength and Full strength). Sterilizing reagents were 35%, 70% alcohol and 2.6% sodium hypochlorite. The sterilizing duration was 10, 20, and 30 minutes. Softwood, semi-hardwood, hardwood, and root cuttings were introduced in a non-mist propagator using soil inoculated with mycorrhizae. Data recorded include germination percentage, moisture level, MS concentration, sterilizing reagent concentrations and time used to sterilize the seeds, temperature, and humidity in the propagator and sprouting percentage of cuttings. Standard procedures were used to analyze and compare germination and rooting data as described by Zar, [1]. The highest germination in the soil was 21% while that of the MS was 19.8%, rooting was 100% in softwood cuttings and 37% in root cutting while semi-hardwood and hardwood cutting didn’t root at all. The two germination mediums (soil and MS) did not differ significantly while using cuttings implies harvesting of the existing forests which is not recommended. More investigations especially genetic transformation of the species for easy access in tissue culture are needed to improve seedling production of D. melanoxylon for the propagation of the species.
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    A Review of the African Blackwood Dalbergia melanoxylon, Guill. and Perr
    (Book Publisher International, 2021-06-01) Washa B., Washa
    The African Blackwood Conservation Project (ABCP) in Tanzania conducted a review of the literature on D. melanoxylon (African Blackwood) or Mpingo in the late 1990s (over twenty (20) years ago). Additionary, It is nineteen (19) years since the last population study and population density was conducted and seventeen (17) years since last inventory study was taken. Today studies on propagation, tissue culture, population and harvesting activities of the species have brought new information to be noted. Recent research on this species' propagation methods has piqued the interest of researchers, who are now looking forward to how they can save the species from becoming threatened or extinct, which can be caused by its low regenerative ability in natural environments. It was now a proper time to add new information to the literature of D. melanoxylon from various recent findings covering about thirteen (13) years from the last review of the literature of the species from 2000-2014 and now is (20) years ago from 2000. This literature review was written to provide useful information for researchers looking into advanced propagation strategies for this species, such as tissue culture and mycorrhiza association, as well as recent studies on the species. This review has also exposed the threats of the species, recent population status of the species in Tanzania, recently recommended research to be taken in consideration, ethnobotanical and ecological literatures as previous and early findings were not able to take botanists to the advanced propagation techniques which have been reported recently and finally Biology and silviculture of Dalbergia melanoxylon.
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    Toxicity Assessment of the Crude Ethanolic Pod Extract of Swartzia madagascariensis Desv. in Rats
    (College of Natural and Applied Sciences, University of Dar es Salaam, 2022, 2022-06-15) Washa B., Washa
    This study assessed toxicity of the crude ethanolic pod extracts of Swartzia madagascariensis Desv in Wistar rats. Forty (40) Wistar rats aged 8–10 weeks were orally administered with crude extracts from pods of S. madagascariensis. Chemical analysis of serum and histopathology of liver and kidney from test animals were performed to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine in serum. In addition, serum albumin levels were also determined. The levels of ALT, AST and creatinine were found to be high in groups treated with crude extracts compared to the control group, suggesting some damage in liver cells and kidney of treated groups of Wistar rats. The albumin levels in serum samples of crude extract treated groups were found to be low compared to control group, suggesting some leakage to the urine due to damage in the kidney. Histopathological analyses revealed damages in the liver and kidney treated with 1000 mg/kg of crude ethanolic pod extracts of Swartzia madagascariensis (CEPES) at days 2 and 14, corresponding to what was observed in the biochemical variables. The findings revealed that Swartzia madagascariensis pods are toxic once taken in large quantities (1000 mg/kg).