Diversity assessment of sweetpotato germplasm collections for yield and yield-related traits in western Tanzania

ABSTRACT

The experimental system: Sweetpotato (Ipomoea batatas [L.] Lam.) is an important food crop widely grown under low input production systems and harsh growing environments. It is a relatively drought tolerant crop attaining higher biomass production per unit area. Genetic diversity present in breeding populations is a raw material for selection of parental genotypes with desirable and complementary traits. The objective of this study was to determine the genetic diversity present among Tanzania grown sweetpotato germplasm to select promising breeding parents with enhanced yield and yield-related traits and dry matter content. Procedures: Seventy six sweetpotato accessions collected from Tanzania and 20 sweetpotato accessions received from International Potato Centre (CIP) in Lima/Peru were characterized in two seasons. The study was conducted using a 16 x 6 triple lattice design. The data collected included 16 morphological traits using CIPs standard descriptors. Data were analysed using multivariate procedure including cluster analysis and principle component analysis. Results and conclusions: The tested sweetpotato collections differed significantly for storage root yield, dry matter content (DMC) and number of roots per plot. Genotypes New Kawogo, Kiti cha Nyerere and Kisu cha Masai had the highest root yields whereas genotypes Ngw’anangusa, Rugomoka and Secondary had significantly higher mean DMC. Traits considered in the study revealed positive and significant correlations. The first four principal components accounted for 69.33% of the variations present in the tested sweetpotato genotypes. Cluster analysis grouped the studied genotypes into two major classes with genetic diversity of 0.54. The selected genotypes can be recommended for future breeding programs to bolster yield and dry matter content of sweetpotato under western Tanzania conditions.

KEYWORDS:

• Dry matter content
• genetic diversity
• morphological traits
• sweetpotato
• western Tanzania

Acknowledgements

Gratitude is due to the International Potato Center (CIP) and Ukiriguru Agricultural Research Institute (ARI Ukiriguru) for sharing sweetpotato germplasm. The first author is grateful to the Tanzanian Ministry of Agriculture, Livestock and Fisheries through Tumbi Agricultural Research Institute (ARI-Tumbi) for providing leave of absence and research support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Mr. Filson Mbezi Kagimbo is currently working with Tanzania Ministry of Agriculture, Livestock and Fisheries at a position of “Senior Agricultural Research Officer” since 2006 to present. He is under the department of Research and Development in Root and tuber crops sub-program. His main duties include generation and dissemination of different agricultural technologies to agricultural stakeholders; conducting seminars and other training to agricultural stake holders; conducting agricultural research work, data collection, analysis and technical report writing. Mr. Kagimbo is currently undertaking his postgraduate studies (PhD) in Plant breeding in his final year at the University of KwaZulu-Natal in South Africa. The course started in January 2014 and the main focus is breeding sweetpotato varieties with resistance to sweetpotato weevils. This course is funded by the Alliance for a Green Revolution in Africa (AGRA) through African Centre for Crop Improvement. Previously, Mr. Kagimbo graduated with MSc. in Agricultural Science in 2011 at the University of Melbourne in Australia. Mr. Kagimbo also graduated with BSc. in Agronomy in 2005 at Sokoine University of Agriculture.

Professor Hussein Shimelis (Ph.D.) is a Crop Scientist with a specialization in Plant Breeding. He is Chair of Crop Science, Associate Professor of Plant Breeding and Deputy Director of the African Center for Crop Improvement (ACCI) at the University of KwaZulu-Natal, South Africa.

Dr Julia Sibiya is a Senior Lecturer in Plant Breeding, SAEES, University of KwaZulu-Natal (UKZN) in Pietermaritzburg (from 2015 to current). She received her BSc. Honours degree in Crop Science from the University of Zimbabwe, MSc in Plant Pathology from the Ohio State University, USA and PhD degree in Plant Breeding from the University of KwaZulu-Natal (UKZN), South Africa. Dr Sibiya spent 10 years as a lecturer in Plant Pathology at the University of Zimbabwe before joining UKZN’s African Centre for Crop Improvement (ACCI) in 2005 as a PhD student (Plant Breeding), and then as a lecturer from 2011 to July 2015. Dr Sibiya lectures modules in Plant Breeding including Biotechnology in Crop Improvement and Plant Breeding Design and Management. She also supervises PhD students from different African countries in the ACCI. Her research focus is on breeding for biotic stresses such as diseases in various crops, particularly foliar diseases of maize and development of unique maize source germplasm, as well as sterile sorghum lines to be used in breeding for sorghum hybrids. Dr Sibiya is also the project manager of a MSc in Plant Breeding for Africa project (Improved Masters in Cultivar Development in Africa – IMCDA) funded by the Alliance for a Green Revolution in Africa (AGRA). The MSc program focuses on training industry-ready, middle-level, graduates from the Southern African Development Community (SADC) and is a joint project with Iowa State University (ISU) (curriculum development) and African partner universities – Makerere University and Kwame Nkrumah University of Science and Technology responsible for training for East and West Africa, respectively. She is also the local coordinator of the Intra Africa Academic Mobility – Mobreed project funded by the EU which focuses on training PhD and MSc students in breeding of orphan or under-utilized crops.

Additional information

Funding

This work was financed by the ‘Alliance for a Green Revolution in Africa (AGRA)’ through the ‘African Centre for Crop Improvement (ACCI)’; ‘[PhD funding]’.