| dc.description.abstract | Edible yams are widely cultivated staple food crops in the tropics, but their production is constrained by low multiplication ratio, which results in short supply of Seed Yam Tubers (SYT). The use of High-ratio Propagation Technologies (HrPT) could enhance quality and quantity of SYT. However, limited information is available on the use of HrPT and the amenability of yam varieties to HrPT for SYT production. In this study, the uses of some HrPT for quality SYT production in Dioscorea alata and Dioscorea rotundata were investigated. Three HrPTs: Conventional Tissue Culture (CTC), Aeroponics System (AS) and field-based Yam Minisetts Technique (YMT) were evaluated for yam propagation using standard procedures. Five yam varieties (TDr9519177, TDr9518544, TDr8902665, TDa291 and TDa9801176) cultured in six growth media [4.43 g/L Murashige and Skoog (MS) basal medium and 7.0 g of agar-agar supplemented with each of 30 g/L sucrose-M1, 60 g/L sucrose-M2, 0.1mg/L Jasmonic Acid (JA)+30 g/L sucrose-M3, 0.1 mg/L JA+60 g/L sucrose-M4, 1mg/L-Naphthalene Acetic Acid (NAA)+30 g/L sucrose-M5 and 0.1 mg/L NAA+60 g/L sucrose-M6] using three light types [blue-Light Emitting Diode (LED), red-LED and white-LED] in CTC experiment were evaluated for Number of Nodes-NN, Number of Vines-NV and Vine Length-VL (cm). Explants from Acclimatised Tissue Cultured Plants-ATCP, Direct Vine Cuttings-DVC and Rooted Vine Cuttings-RVC of the five yam varieties were grown in AS and evaluated for Plant Survival-PS, Number of Tubers-NT and Fresh Tuber Weight-FTW (g). Using the YMT, four D. alata and 12 D. rotundata varieties were evaluated on the field using five Sett Weights-SW (10, 20, 30, 40 and 50 g). Data on Plant Emergence-PE (%), NT, SYT (%) and Fresh Tuber Yield-FTY (t/ha) were analysed using descriptive statistics and ANOVA at α 0.05. Across varieties, NN, NV and VL differed significantly among media and light types. The NN, NV and VL ranged from 3.3±0.9 (M6, red-LED) to 15.9±1.1 (M3, white-LED), 1.2±0.3 (M2, Blue-LED) to 3.2±0.8 (M4, white-LED) and 4.3±0.9 (M6, red-LED) to 10.5±1.0 (M6, red-LED), respectively. The PS, NT and FTW varied significantly among yam varieties and explant sources. The PS across varieties was in the order: ATCP (52.0±14.5)>DVC (35.4±11.6)>RVC (28.3±16.0). The NT ranged from 12.3±0.6 (TDa9801176, DVC) to no tuber (TDa291, RVC). The FTW obtained from ATCP, DVC and RVC ranged from 6.2±15.1 (TDa291) to 257.8±3.2 (TDr9518544), 0.0 (TDr8902665) to 157.0±3.5 (TDr9518544) and 0.0 (TDa291) to 147.8±3.3 (TDa9801176), respectively. Effects of variety, SW and variety×SW interaction in YMT were significant on PE, NT and FTY. Across SW, PE declined from 97.7±9.5 (TDa9801176) to 40.5±7.6 (Danacha). Across varieties, NT ranged from 13.1±1.3 (10 g SW) to 20.3±3.8 (50 g SW), while FTY ranged from 8.6±2.6 (10 g SW) to 20.7±4.3 (50 g SW). The proportion of SYT was highest (66.9±6.0) in 20 g SW and lowest (55.1±13.1) in 50 g SW. Jasmonic acid supplemented medium, white light emitting diode, tissue culture plants, sett weights of 20 g and varietal effect enhanced propagation and seed yam tuber production in Dioscorea alata and Dioscorea rotundata. |
| cg.contributor.acknowledgements | All glory and honour to God, the immortal, the invisible, the only wise; by whose infinite grace and mercy I have my being and progress.
I would like to express my profound gratitude to my supervisor and mentor, Prof. M.O. Akoroda of the Department of Crop and Horticultural Sciences, formally Department of Agronomy, University of Ibadan. Sir, I am forever grateful to him for accepting to supervise me despite the heavy demand of his office as the Executive Director of Cocoa Research Institute of Nigeria (CRIN), Ibadan, Nigeria. The Anthem "see all, read all, edit all," which he taught me since the M.Sc. days, kept resonating as I prepared this thesis, line by line, word for word. I appreciate my co-Supervisor, Dr. N. G. Maroya, Project Leader, Yam Improvement for Income and Food Security in West Africa (YIIFSWA), International Institute of Tropical Agriculture for the Scholarship offered me his immense support and patience throughout the period of this study.
I am also highly grateful to Prof. Bola. A. Olaniyan of the Department of Crop and Horticultural Sciences, University of Ibadan and Dr. Morufat. O. Balogun of the Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, for their guidance, comments, and suggestions in preparing this thesis. I thank the aforementioned for being the driving force behind this work. Professor Dr. ir. S. Werbrouck of the Department of Applied Bioscience Laboratory of Applied in vitro Plant Biotechnology, University of Ghent, Belgium, is highly appreciated for the warm reception and mentorship he offered during my visits to his Laboratory to conduct part of this study. The entire staff at this Laboratory are highly appreciated for their assistance. To all these mentors mentioned here, your painstaking efforts and contributions to the successful completion of this study will forever be in my sweet memory. Again, I thank them for believing in me and for the training I had the privilege to receive from them.
I am so grateful to Dr. R. Asiedu, the IITA Yam Community of Practice and IITA-BMGF/YIIFSWA project, for the scholarship offered to pursue this study. I also thank Dr. H. Kikuno, who was my first Instructor at IITA Ibadan, Nigeria, for the training and exposure I had under his watch when I joined IITA as an Industrial Trainee and later as a fresh graduate and as an M.Sc. fellow. Teachers are gods. Gratitude and appreciation to eminent scholars from whose fountains of knowledge I drank to gain knowledge and rectitude are a demand of my present academic status. I appreciate Prof. J. A. Fagbayide, the Head of the Department of Crop Science and Horticulture University of Ibadan, Ibadan, Nigeria, for his commitment to completing this Ph.D. study. I thank Professor V. O. Adetimirin for recommending my admission to the graduate college while serving as the Head of the Department of Agronomy, which is now split into the Departments of Crop and Horticultural Sciences and the Department of Soil Resources Management. I will forever be grateful to him for the privilege to pursue my postgraduate study at this prestigious University. I wish I could find enough words to appreciate Dr. S. O. Osunsanya for his immense sacrifices in registering my abstract and this thesis from the Department up till Postgraduate College. I thank him for being the driving force behind the registration of this thesis at the postgraduate college University of Ibadan, Nigeria.
My sincere appreciation goes to the Departmental lecturers: Professors M. E. Aken'Ova of blessed memory, G. O. Adeoye (retired), A. O. Ogunkunle (retired), H. Tijani-Eniola, E. A. Aiyelari, G. E. Akinbola, O. Fagbola, K. O. Oluwasemire, as well as Drs. O. O. Adeoluwa, A. Abe, B. Olasanmi, J. R., Orimoloye, E. Y. Thomas, O. W. Olaniyi, Akinrinola and Engr O. A. Sadiku for their tremendous support. The Non-Academic Staff and others who have contributed to the success of this academic journey are well appreciated.
The supports given by Messrs M. Oyetayo and J. Taiwo in the field, Aeroponics and Temporary Immersion Bioreactor Systems experiments is highly appreciated. I express my gratitude to Drs A. Paterne, M. G. Akinwale, N. A. Adetoro, and O. Alabi for the motivation and encouragement received. I thank Messrs T. Ayankanmi and O. Azeez for their tremendous assistance. Also appreciated for their supports are Messrs Adeosun Tunde, A. Kabiru, A. Edumodu, T. Olusola, I. Adejumobi, Y. Kolombia, and the entire membership of the Yam Barn at IITA.
Also worthy of appreciation are my colleagues in the Agronomy Club, University of Ibadan, the International Association of Research Scholars and Fellows (IARSAF-IITA). A. A. Bello and E. Oketade are well appreciated for their immense contribution towards the success of this work while drinking together from the well of knowledge of our supervisor (Prof. M. O. Akoroda).
I express my profound appreciation to Reverend S. I Ajetomobi, Pastor (Dr) S. Ajayi, other Pastors and brethren of the Redemption Faith Church Ibadan for their prayers and encouragement. I cannot but recognize the immense contributions of my good friends, A. Oluwamuye, S. Ogidan, O. Amusa, B. Odewumi O. Ajayi, O. Akanbi and O. O. Fayemi, towards the successful completion of this program. To all who have supported me in one way or the other in the course of this program, I pray God in his infinite mercies to bring great helpers your ways. I thanked Dr. S. Adeleke, Elders J. Uponi, P. Igboba, W. Odianarewo, Dr. E. Parkes, I. Odey, O. Akinboade, B. A. Ojelade, C. Okoruwa and all other members of the IITA Bible Study Group for their prayers and words of encouragement.
May I now register my heartfelt thanks to my wife, Abosede Esther Pelemo, for her companionship, love, and support throughout the course of my study. Masters Ayoola Cornelius, Erastus Oladipupo, and my girl Eniola Emmanuella are all appreciated for enduring my absence during my research trips to the University of Gent, Belgium. I am greatly indebted to them all. I am eternally grateful to my parents, Late Most Senior Apostle Prophet Andrew Tolorunloju Pelemo and Beatrice Pelemo. They denied themselves the comfort and pleasure of this World to raise my siblings and me. Their prayers, counsels, and sacrifices were inestimable. The unflinching supports received from my siblings: Mr. M. A. Pelemo, Ms. Olayinka A. Andrew, Architect S. O. Andrew, Mr. O. J. Andrew, Mrs. Olabimpe. A. Adeyeri, Mr. A. O. Andrew, Ms. Oluranti Andrew, and Mrs. Olufisayo. O. Babanola were instrumental to the psychological strength and vigour that fuelled and sustained this academic pursuit. I thank my cousin: Ogunsakin Oluwasesan, for being there for me always especially at crucial times.I am most grateful to them all. I am also thankful to uncle Jimola Pelemo who was a source of encouragement to me in my academic pursuit. |
