SILVICULTURAL AND CONSERVATION TECHNIQUES FOR Khaya grandifoliola C. DC. IN SOUTHERN NIGERIA

Khaya grandifoliola, an important economic hardwood species, has been severely depleted by overexploitation. This necessitates its ex-situ conservation and requires in-depth knowledge of nursery handlings, seed storage, in-vitro and ex-vitro propagation on which information is sparse. Therefore, silvicultural requirements for conservation and sustainable use of K. grandifoliola in some parts of southern Nigeria were investigated in this study. Seeds of K. grandifoliola were purposively sourced from forested areas of Cross River (Boki and Kutia), Ondo (Ayegunle-Akoko, Oba-Akoko and Owo) and Oyo [National Centre for Genetic Resources and Biotechnology (NACGRAB), Ibadan] states and assessed for length, width and weight. Freshly collected (Control) seeds (n=100) were tested for viability using standard procedure. Seeds (n=100) from each of the sources were planted and 30 competitive seedlings were assessed for growth characters. Seeds (n=2000) were selected and 500 each were stored for 20 weeks at Ambient Room Temperature (ART: 28.0±2.0o C), Short Term genebank (ShT: 24.0 o C), Freezer (FrZ: - 6.0 o C) and Long Term genebank (LgT: -17.0 o C). Monthly, seeds (n=100) were randomly selected from the four storage conditions and sowed in sterilised river sand for viability test. Single node cuttings treated with Indole Butyric Acid (IBA), Napthalene Acetic Acid (NAA) and Indole Acetic Acid (IAA) at (0, 25, 50, 150 and 200 mg/L) using sand, sawdust and 1:1 sand-sawdust were assessed for macropropagation. In-vitro culture of embryo on Murashige and Skoog (MS) medium + Benzyl Amino Purine (BAP) + NAA + Adenine Sulphate (ADS) was studied. Deoxyribonucleic Acid (DNA) samples were collected from juvenile leaves of K. grandifoliola from the 30 competitive seedlings and tested for molecular genetic diversity using six Random Amplified Polymorphic DNA (RAPD) (OPD-08, OPD-11, OPD-13, OPA-18, OPD-18, and OPD-20) primers. All experiments were laid out in completely randomised design. Data were analysed using descriptive statistics and ANOVA at α0.05.