PhD Theses

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Browsing PhD Theses by Author "Amri, Ezekiel"

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    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.