Improving sweetpotatoes for larger markets in Uganda

Bernard Yada is a sweetpotato breeder with Uganda’s National Agricultural Research Organization (NARO). In this interview, he speaks to Vivian Atakos, a communications specialist from the International Potato Center (CIP), to discuss the progress his team has made within the Sweetpotato Genetic Advances for Innovative SeedSystems (SweetGAINS) project.  

(This is an updated interview from their first discussion in in July 2020) 

Yada inspects some sweetpotato planting materials in a screenhouse in Uganda. (photo: NARO Uganda)

Q: When we last spoke, you talked about the contributions of sweetpotatoes to Uganda’s agri-food systems, the problems you are trying to solve through breeding, and some of the aspects of modernizing breeding.  

Today, let us look at another aspect of modernizing plant breeding—product profiles. What are product profiles and why are they useful? 

Yada: A product profile is a new way of planning breeding objectives. It is a breeding blue print. First, you identify your market leading variety and the good traits in it—the basic traits. Then you decide what traits you need to add into a variety under development so that the new variety (when released) can replace the market leader. So, those traits—we call them value-added traits—should give it an edge over the market leader. And, the principle is that these traits should not be too many. They should be a maximum of three. 

Q: Why? 

Yada: You are not going to be breeding for the same thing in ten years as needs change quite fast. We expect CIP to deliver a new variety within a maximum of five years for the annual crops like sweetpotatoes (which can be grown twice a year) and a maximum ten years for perennials (like bananas, which are only grown once a year). 

Q: So, who is involved in the development of product profiles? 

Yada: You involve multi-disciplinary stakeholders—a multi-functional team along the value chain right from production up to processing.  

Q: Now at two years into SweetGAINS, what progress has been made with product profiles in Uganda?  

Yada: We already developed a product profile for Uganda under the guidance of the CGIAR Excellence in Breeding platform. We started from 2018 before SweetGAINS came on board and by 2019 we already had a product profile. It took about one year.  

Q: Which is the market leading variety in Uganda and what traits are you looking to add into it? 

Yada: We have three pipelines we are focusing on: white to cream, orange-fleshed and purple-fleshed. Cream varieties are mainly consumed as boiled, and the market value presently constitutes of over 80% of what is being marketed in Uganda. The market leader of the cream variety is NAROSPOT 1, which is also called New Dimbuka by farmers.  

Q: And what are you adding into NAROSPOT 1

Yada: We want to enhance its sweetpotato weevil and sweetpotato virus disease resistance, and to reduce oxidation because when you cut it, it tends to turn black. 

Q: And in terms of the weevil and virus resistance, how big is that problem?  

Yada: This variety has moderate weevil resistance and when left in the field for some time, weevils can cause severe damage to it. 

Q: Are these traits gender-responsive? Do they reflect needs of the women, men, and youth?  

Yada: We held a specific activity to ensure gender-related traits are factored in. We discussed aspects such as the root shapes, which affect packaging and skin smoothness among others.   

Q: Let’s move on to the orange-fleshed pipeline. 

Yada: Presently we are replacing NASPOT 8, which is moderately resistant to sweetpotato weevils and has relatively low beta-carotene content. We are, therefore, increasing its beta-carotene content to over 200 micrograms per gram on dry weight basis, and improving the storage root shapes and skin smoothness. 

Q: And what impact will this be on the mealiness? 

Yada: This work may impact the dry matter content because these two traits normally keep going in the opposite directions. We are, however, able to select some materials which normally combine both high dry matter and high beta-carotene content. We also want to improve the shapes, skin smoothness and beta carotene, especially for the orange-fleshed to meet export market needs.   

Q: What about the processing? The NASPOT 8. Is it mainly for just export? Next we move to the purple varieties.  

Yada: The processing bit comes when we improve the orange fleshed. Then for purple, presently we don’t have a formerly released variety in Uganda. We however have landraces, which farmers are producing. We want to increase the anthocyanin content in these varieties, by doing crossings with materials from other breeding programs. We are also looking at the storage root shapes as well as resistance to weevils and viruses. 

Q: Thanks. You mention something on accessing materials from other breeding programs. Which are these breeding programs and as a breeder, how do you access these materials? 

Yada: The major focus is the purple and we access these materials from North Carolina State University who have a fully functional purple pipeline.  

Q: The International Year of Plant Health ends 1 July 2021. It would be nice to hear from you any challenges you experienced in transporting these materials.  

Yada: Generally, we are dealing with vegetative materials and these can carry viruses, diseases and pests. However, we follow some stringent measures put in place by the sending and the receiving countries. The materials must be clean of all viruses, pests and diseases and confirmed. The stringent measures can at times make it difficult to access these materials. In such cases, then we go the seed route. Research has shown there is minimal transmissional of pests through seed. 

Bernard Yada, a plant breeder in Uganda, is working on three pipelines of sweetpotato in support for the SweetGAINS project in Africa. (photo: NARO Uganda)

Q: Great. I have understood a lot about your work.  Do you have anything happening on ground in Namulonge?  

Yada: One of the key things we are doing is the proof of concept for genomic selection. Currently, we have training population, which we are maintaining at the screen house and evaluating in the research fields at Namulonge, Serere and Abi (NARO research institutes).  

Q: How long will this work take? 

Yada: This is supposed run through the end of next year. Because the next thing you must do is genotyping, which is supposed to be done at North Carolina State University. After genotyping, then you get the field data and genotyping data to develop a model for predicting the next set performances of the offspring for those traits. We also have the parents in this training population planted in a crossing bloc. So, we are going to generate seed and offspring from these parents. We are going to use the prediction model that we are going to generate from the training population to predict the performance of the offspring being generated from the current crossing block. These are some of the key activities going on here. 

Q: Great work! All the best and thanks for speaking to me. 

Yada: Thank you Vivian.