Browsing by Author "Amri, Ezekiel"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Investigation on the propagation potential of dalbergia melanoxylon guill & per. (African Blackwood) provenances and their genetic diversity from selected areas of Tanzania
    (University of Dar es Salaam, 2009) Amri, Ezekiel
    The objective of this study was to investigate means of optimizing both vegetative and seed propagation techniques and evaluation of genetic diversity of Dalbergia melanoxylon Guill. & Perr. (African Blackwood) provenance from the Eastern part of Tanzania. The effect of cutting position, age of donor plant, rooting media and provenance were investigated. The effect of timing of seed collection on seed germination was also investigated. Randomly amplified polymorphic DNA (RAPD) analysis was used to determine the genetic diversity of D. melamoxylon populations. Significantly (p˂ 0.05) high rooting ability 71.11% was achieved for basal cutting position from juvenile donor plant treated with IBA at 300 ppm. River sand was significantly (P˂ 0.05) ranked the best rooting media for stem cuttings. Germination capacity and germination were significantly high for seeds collected 12 and 16 weeks after maturity. Significant variation in rooting ability and seed germination were revealed among the provenances of D. melanoxylon. RAPD primers amplified 87 scored bands which revealed 73.6% polymorphism and cluster analysis using UPGMA formed four major clusters. The genetic diversity within populations was 63.6% and among population was 36.4%. it was concluded that basal position cuttings of the juvenile donor plants and river sand rooting media should be used for vegetative propagation. Timing of seed collection in D. melamoxylon should be from 12th to 16th week maturity to obtain seeds with high viability and germination capacity. Genetic diversity revealed in D. melanoxylon is still high, therefore domestication and sustainable utilization was recommended for preservation of genetic diversity of this economically important tree.
  • No Thumbnail Available
    Item
    Propagation studies of economically important plants: dalbergia melanoxylon, Swantzia Madagascariensis (Papilionaceae) and prunus Africana (Rosacea)
    (University of Dar es Salaam, 2002) Amri, Ezekiel
    Dalbergia melanoxylon and Swartzia madagascariensis are in danger of commercial extinction due to over exploitation. Few efforts have been reported on enhancing propagation of these threatened plants. This research was an effort to evaluate easy, mass propagation techniques through seeds and rooting of stem cuttings for conservation use. Seed germination experiments for Dalbergia melanoxylon and Swartzia madagascariensis were conducted under laboratory conditions. Both species germinated best at temperature between 25°C and 30°C. Seeds were treated with boiling water for 1 min, 5 min, 10 min and 15 minutes. The best germination results (85%) were obtained from seeds of Swartzia madcrgascariensis immersed in boiling water for 5 and 10 minutes. Mechanical scarification, dry heat scarification at 80°C for 30 minutes, 100°C for 15 minutes and sulphuric acid treatment for 10 minutes also enhanced germination from 56% up to 78% in Swartzia madagascariensis. Less favourable results were obtained for Dalbergia melanoxylon for all scarfication treatments. Seed stratification for two weeks significantly increased germination in Dalbergia melanoxylon, Stratification treatment was completely ineffective in Swartzia madagascariensis. Root initiation on stem cuttings by exogenous applications of growth hormones (IBA, NAA) was studied. IBA at 300 ppm yielded higher rooting percentage for D. melanoxylon and S. madagascariensis. For Prunus africana IBA 500 ppm was effective in increasing rooting percentage and the number of roots per cutting. Seasonal rooting of stem cuttings was significantly higher in dry season than in rainy season for D. melanoxylon and S. madagascariensis. Long stem cuttings (20 cm) produced significantly more roots compared to the short stem cuttings (10 cm) in all three species. These results have significant implications for conservation of these threatened plants.