| dc.contributor.author | Adegboyega, T.T. |
| dc.date.accessioned | 2022-10-11T15:07:39Z |
| dc.date.available | 2022-10-11T15:07:39Z |
| dc.date.issued | 2019-07 |
| dc.identifier.citation | Adegboyega, T.T. (2019). Genetic diversity and nitrogen fixation in underutilized tropical legumes. Potchefstroom, South Africa: North-West University, (185p.). |
| dc.identifier.uri | https://hdl.handle.net/20.500.12478/7858 |
| dc.description.abstract | Legumes in some cases are underutilized and form only a relatively small proportion of human diets. In general they fix atmospheric nitrogen which may provide an economic advantage for smallholder farmers. By appropriate utilization of legumes, food security and soil fertility can be significantly achieved. During the 2016/2017 and 2017/2018 cropping seasons at the International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria, field and laboratory experiments were conducted to determine the genetic diversity and nitrogen fixation of two underutilized tropical legumes, winged bean (Psophocarpus tetragonolobus (L.) DC.) and African yam bean (Sphenostylis stenocarpa (Hoechst ex. A. Rich.) Harms). Twenty-five accessions of each crop were used for these experiments without rhizobia inoculation or N fertilization. In each season, randomized complete block design (RCBD) was used for the filed experiments in three replications. This study confirms characters that can be used to improve African yam bean germplasm include dry pod weight, number of seeds per pod, leaf rachis, terminal petiole length, and seed length. African yam bean fix N and nodulate with indigenous soil bacteria. TSs77 fixed the highest amount of N at 22.47 kg ha-1 followed by TSs30 at 20.91 kg ha-1 and TSs101 at 19.80 kg ha-1. These top three accessions can be identified for breeding programs as superior N-fixing accessions. The protein content of the accessions showed significant differences. For instance, TSs104 had the highest protein content of 25.08%; followed by TSs76 (24.82%), TSs1 (24.52%), TSs4 (24.31%), and TSs67 (24.24%) while the accession with the lowest protein contents in the processed seeds was TSs30 (22.02%). However in the unprocessed seeds, protein content ranged between TSs38 (24.93%) and TSs11 (19.13%). Other proximate analyses evaluated showed differences among the accessions; there were reductions in the unprocessed seeds for phytate and tannin contents. Evidence of the nutritional content of these crops as observed in this study implied that they can be utilized in various dishes for adults and children, to reduce malnutrition in sub-Saharan Africa. No rhizobia were isolated but other isolated root nodule-associated bacteria were analyzed using morphological, biochemical and 16S rRNA. The molecular analysis revealed the presence of Kosakonia oryzae; Enterobacter asburiae; E. cloacae; Ralstonia pickettii; Variovorax sp. and Hydrocarboniphaga effuse. The specific roles of these associated bacteria were not ascertained but previous reports suggest they may assist in plant growth and development. The δ15N signatures of the legume differed among accessions and varied from 2.52 (TSs61) to 0.24 (TSs44) in the shoots and from 2.70 (TSs98) to 0.82 (TSs16) in the roots. Significant differences were recorded among the reference plants used for estimating the percentage N derived from the atmosphere (Ndfa) of African yam bean shoots. TSs76 had the highest Ndfa of 66.73%, 51.83%, and 63.48% followed by TSs4 with 66.18%, 51.03%, and 62.87% while the lowest was TSs1 with 40.07%, 13.22% and 34.21% when Eleusine indica, Zea mays, and Tridax procumbens were used respectively for estimation. The δ13C values of shoots were much greater (i.e., less negative) while the values for the roots also varied considerably. Consequently, the δ13C values of African yam bean shoots ranged from -31.49 (TSs98) to -30.93 (TSs4) and from -31.16 (TSs68) to -30.20 (TSs4) for the roots. The observed variation indicated differences in water-use efficiency among the accessions. The carbon and N ratio (C/N) values were lower than 24 gg-1 and the reference plants had over 24 gg1. These outcomes support the opinion that photosynthetic activities in the underutilized legume were stimulated by N nutrition. TSs44 has a significantly higher number of nodules than other accessions at 169.67 while TSs23 had the lowest number at 58.42. The use of 15N natural abundance method in determining N fixation and water-use efficiency in African yam bean is the first report to the best of my knowledge.
The winged bean accessions evaluated possessed the potential to fix nitrogen and also nodulated with indigenous soil bacteria. GCV were high for pod length, dry pod weight, estimated number of seeds per pod, total number of seeds and seed weight. The high GCV suggests that these characters can easily be selected for improvement. In the processed seeds, Tpt17 had the highest protein content of 40.30%, followed by Tpt11 (39.72%), Tpt43 (39.35%), Tpt15-4 (39.21%), and Tpt4 (38.88 %); the lowest was recorded in Tpt48 (34.18%). In the unprocessed seeds, Tpt17 also recorded the highest crude protein content at 31.13%, followed by Tpt4 (31.02%), Tpt15-4 (30.84%), and Tpt42 (30.62%) while the lowest was contained in Tpt125 (28.43%). Other proximate composition analyses suggested that winged bean could serve as a complementary item in human diets and animal feed. In the swollen roots (tubers) and seeds, processing was observed to lower the levels of anti-nutrients. The δ15N values of winged bean showed great differences among the accessions and varied from 3.34 (Tpt18) to 0.86 (Tpt3-B) in the shoots and from 3.07 (Tpt15) to 0.49 (Tpt32) for roots. Among the reference plants used for estimation the percentage Ndfa of winged bean shoots also varied significantly between 66.12% (Tpt3-B) and 24.3% (Tpt18). Differences were seen in the estimation of the roots. The amount of nitrogen fixed differed significantly (p ≤ 0.05) among accessions. The amount fixed (kgN ha-1) in the shoots varied among the accessions with Tpt32 fixing 27.16 kg ha-1, followed by Tpt15-4 at 25.66 kg ha-1 and the accession fixing least was Tpt30 that measured 9.02 kg ha-1 with a considerably lower amount fixed in the root. Variation exists in the carbon and N ratio among the winged bean accessions studied when compared with other parameters analyzed. Overall, the C/N ratio for the shoots ranged from 15.87 (Tpt51) to 11.97 (Tpt32) and from 18.33 (Tpt12) to 17.83 (Tpt53) for the roots. The δ13C values of winged bean shoots ranged from -30.60 (Tpt48) to -29.62 (Tpt19) and from -30.17 (Tpt53) to -19.19 (Tpt6) for the roots. The values obtained showed these accessions were generally stable in their expression of water-use efficiency. Winged bean root nodule-associated bacteria isolated from winged bean roots were Enterobacter asburiae; E. bugandensis; E. cloacae; Enterobacter sp; Enterobacteriaceae bacterium; Pseudomonas cremoricolorata and P. fluorescens. Others are P. montellii; P. putida; Kosakonia oryzae; Ralstonia sp; and an uncultured bacterium clone. Rhizobia recovered from winged bean nodules include Rhizobium mayense, R. multihospitium, R. pusense, and several other rhizobia sp. The rhizobia isolated have been previously confirmed as playing key roles in nodulation and N fixation. This outcome reveals the importance of incorporating legumes in tropical agriculture for crop intensification. Finally, the study provides evidence that African yam bean and winged bean accessions can be improved in a pre-breeding program with respect to the following traits; N-fixing potential, nodulation capacity, proximate and anti-nutritional composition, and diversity in bacteria nodulating the roots. |
| dc.description.sponsorship | International Institute of Tropical Agriculture |
| dc.description.sponsorship | North-West University |
| dc.format.extent | 185p. |
| dc.language.iso | en |
| dc.publisher | North-West University |
| dc.subject | Genetic Variation |
| dc.subject | Nitrogen Fixation |
| dc.subject | Food Security |
| dc.subject | Smallholders |
| dc.subject | Farmers |
| dc.subject | Soil Fertility |
| dc.subject | Legumes |
| dc.subject | Economics |
| dc.subject | Germplasm |
| dc.subject | Seeds |
| dc.subject | Breeding Programmes |
| dc.subject | Proteins |
| dc.subject | Nutrition |
| dc.title | Genetic diversity and nitrogen fixation in underutilized tropical legumes |
| dc.type | Thesis |
| cg.contributor.affiliation | North-West University, South Africa |
| cg.coverage.region | Africa |
| cg.coverage.region | West Africa |
| cg.coverage.country | Nigeria |
| cg.coverage.hub | Headquarters and Western Africa Hub |
| cg.identifier.bibtexciteid | ADEGBOYEGA:2019a |
| cg.authorship.types | CGIAR and developing country institute |
| cg.iitasubject | Agronomy |
| cg.iitasubject | Food Security |
| cg.iitasubject | Food Systems |
| cg.iitasubject | Genetic Improvement |
| cg.iitasubject | Grain Legumes |
| cg.iitasubject | Plant Breeding |
| cg.iitasubject | Plant Genetic Resources |
| cg.iitasubject | Plant Production |
| cg.iitasubject | Smallholder Farmers |
| cg.iitasubject | Socioeconomy |
| cg.iitasubject | Soil Fertility |
| cg.notes | IITA supervisors: Drs. Abberton, M. & Dianda, M. |
| cg.publicationplace | Potchefstroom, South Africa |
| cg.accessibilitystatus | Limited Access |
| cg.reviewstatus | Peer Review |
| cg.usagerightslicense | Copyrighted; all rights reserved |
| cg.targetaudience | Scientists |
| cg.iitaauthor.identifier | Adegboyega Taofeek Tope: 0000-0002-3486-614X |
| cg.futureupdate.required | No |
| cg.contributor.acknowledgements | I give all glory, honour, and adoration to Almighty God for his mercies and abundant grace in
my life. The work presented in this thesis has been possible only through the contribution of
many. I would like to express appreciation to management and staff of the Genetic Resources
Center-IITA through the provision of a graduate research scholarship and North-West
University for Institutional Bursary awards. Many good people at Genetic Resources Center
contributed to my work in many ways, but special thanks are due to Dr Olaniyi Oyatomi for
continuous interest, encouragement, and valuable discussions.
I thank my supervisors, Prof. Babalola, Prof. Abberton, Dr Aziz, and Dr Dianda, from whom
I have garnered a wealth of knowledge. Your enthusiasm, insight, criticism, and
encouragement were invaluable throughout my PhD journey. The roles played by Prof.
Babalola during the fellowship application cannot be overemphasized. She provided the link
for me to study in IITA. Prof. Babalola also provided all the needed financial, moral, and
emotional support by visiting the field and laboratories to monitor the research activities in
Nigeria. I shall be eternally grateful for your constant engagement. I cannot thank Prof.
Abberton enough for guidance and ideas, also for always having ‘regular meetings’ for me
even at the busiest times. Dr Aziz left mid-way for the United States but served as mentor
and field assistant by helping with all field related activities including conveying us from the
field to the office and providing office space and a desktop computer for me in the Soil
Microbiology lab. I greatly benefited from his selfless research activism. Dr Dianda
facilitated the field meeting with Prof. Ken Giller (author of the famous book on Nitrogen
fixation in tropical cropping systems) and offered useful insights towards the improvements
of the study. It was great pleasure to work with you all.During my PhD journey, I learnt so
much from different individuals. Mr Ben Faloye (Field bank Manager) and Mr Sam Korie
taught me experimental field design, mapping, and layout. Mr Ofodile taught me statistical
5
package using SAS and was also ready to help when I ran into confusion. Mr Adebowale and
Mr Adekunle provided implementation support during the two years of field study with the
kind assistance of the GRC screen house team. I would also like to thank Mr Eniola, Mr
Williams, Ms Olaoluwa, Mr Nwachukwu, and Mr Innocent for teaching me how to analyze
soil samples and conduct plant sample analysis and other microbiology related activities. At
the Food and Nutrition Science Laboratory, Dr Maziya-Dizon, Mr Adesokan, Mrs Olaniyan,
and Mr Akin provided useful assistance and technical expertise. At the Bioscience Center, Dr
Andreas (IITA Bioinformatician) and Mrs Iwu taught me bioinformatics and molecular
biology techniques. The brilliant people I was privileged to call my colleagues included
Tesleem, Adenike, Moses, Sani, Khomotso, Comfort, Darkwa Kwabena, and Cobes. Special
thanks to Dr and Dr (Mrs) Aremu for friendship, advice, and good homor and to Dr
Olayiwola for their technical inputs into Chapters 4 and 7. Prof. Steven Bouillon of the
Division of Soil and Water Management, KU Leuven provided training support on the use of
15N natural abundance technique in his laboratory. The staff at the Knowledge Center was
very useful as well (Mr Louis, Mr Austin, and Mrs Ayinla) for providing regular space and
other necessary assistance. I also appreciate the research support provided by the
Communications Unit led by K. Lopez and her team including Mr Juba. Rev. (Dr) and Mrs
Abiodun Aina provided decent accommodation in Akingbile, Ibadan, when I was in Nigeria.
I appreciate the immense support provided by the Deputy-Director General, IITA, Dr MayGuri Saethre, Prof. Olawoye, and Mrs Badejo to the graduate fellowship program and by
extension to the association I led.
Many people outside IITA helped me along the way. I would like to say a big thank you to
peers in the Microbial Biotechnology Laboratory as well as to all the members and staff of
the Department of Microbiology, the past and the present HODs, Prof. Emmanuel Mukvepho
and Prof. Collins Ateba as well as all faculty and staff members of the Faculty of Natural and
6
Agricultural Sciences, North West University, for their immense support. My gratitude goes
to my family in North West University, for their encouragement. Special appreciation is due
to Dr Mobolaji Adegboye, (University of Waterloo, Canada), Dr Bernard Ojuederie (NWU,
South Africa) and Dr Omotola Fashola (LASU, Nigeria) for reviewing the literature review
and for other technical assistance. My thanks go also to Musanchi, Pule Pule, Sandra Horn,
and Tedy for help with registration and bursary clearance among other things. My past and
present teachers at the Olabisi Onabanjo University Ago-Iwoye and University of Lagos
Nigeria were very supportive of my plans to study abroad. I thank Prof. Odunaike (Dean of
Science, OOU), Prof. Adebajo, Prof. Efuntoye, and Dr Agunbiade who provided with visa
support. Comrade Egberongbe (SSANU Chairman) and Dr Egberongbe also provided
relocation assistance. Dr and Dr (Mrs) Gboyega Ilusanya; and Dr Adesetan provided
additional Naira and Rand for use at the airport. The supportive roles provided by Prof. Sade
Ogunsola (Deputy Vice-Chancellor) and Dr Tenny Eqwuatu at the University of Lagos
cannot be overemphasized. The exemplary academic mentorship support provided from the
high school to university days by the Academic Excellence Initiative (AEI) is worthy of
mention. Mr Ayilara, Prof. Adedeji (Uganda), Dr G. Olumuyiwa (Abuja), Engr. Faheed, Dr
Bello (USA), Mr Tijani, Pharm. Bakare and Pharm. Abideen. Last, I salute the cooperation of
my family during my study, and my Dad, Engr. Olasunkanmi for his constant inspirational
pieces of advice. Emotional support was provided by Fehintoluwa, Modupeoluwa, Toyyibah,
Imam Nasir, Tunde, Isiwat and other siblings from the Adegboyega, Akanni, and Adelani
families for always being there for me. I specially appreciate my wonderful treasure Omolola
during my long absence from home and kind assistance to keep the priorities straight and
maintain a proper perspective. I owe you all big time. |
