Analysis of and recommendations for scaling cassava agribusiness seed systems models in Rwanda

The objective of this study was to analyze the scalability of the cassava seed agribusiness models that have been supported under the CASS project in Rwanda. Phone interviews with key-informants formed the basis for analyzing the agribusiness cases. The study presents general conclusions, bottlenecks and recommendations for further development and scaling of cassava agribusiness seed models in Rwanda. General conclusions The key-informant interviews allowed us to draw the following conclusions: 1. None of the seed agribusiness models are currently ready for scaling 2. Agribusiness models are not yet being used beyond the CASS project 3. Likelihood of continued agribusiness model development varies across models 4. There is a lack of strategies or plans that go beyond the CASS project 5. No major concerns regarding the responsible scaling of the agribusiness models are reported, but unclear how the models target different groups of cassava farmers 6. Public-private partnerships seem to be preferred modality for scaling cassava seed agribusiness models 7. The “what’s in it for me” needs to be clarified for key stakeholders Cross-cutting bottlenecks There are a number of sector-wide bottlenecks that could negatively affect the scaling of clean cassava seed agribusiness models in Rwanda: 1. Limited investment in developing the cassava sector 2. Incentives for investing in clean cassava seed are currently not strong enough 3. There exist key capacity gaps among cassava farmers, seed multipliers and cooperatives 4. There is a lack of clear stakeholder scaling role division and coordination 5. Limited understanding of the market for seed and roots 6. Limited information flow and demand creation amongst farmers for new varieties and clean seed Recommendations and next steps The following recommendations and next steps could be considered by the CASS project team: 1. Distinguish between scaling within the agribusiness cases, and scaling the agribusiness models 2. Develop long-term and/or exit strategies with the agribusiness case stakeholders 3. Continued investment in fine-tuning those models that seem promising 4. Deepen understanding of stakeholder willingness to pay/invest 5. Co-investment models with scaling partners to ensure ownership and sustainability The above conclusions, bottlenecks and recommendations are in line with the main objective of the CASS project which was to “develop, test and tailor different types of cassava agribusiness seed system models with and for different groups of farmers”. The nature of development, testing and tailoring implies by default that some models will show more 2 potential for sustainability and scaling than others. We would like to emphasize that this is normal and what should be expected when designing and piloting new seed system models. The scaling recommendations and bottlenecks identified in this report should therefore be interpreted as giving an early indication of how key-informants perceive the scalability potential of the various cases and models. Bottlenecks or risks should not necessarily stop agribusiness case or model development, but taken into account when making decisions on which case and model development to continue and how. What is very important is to see projects such as CASS as temporary interventions that can support capacity sharing, stakeholder collaboration or independent agribusiness seed model testing. Project teams and broader stakeholders should always think beyond the project to ensure that there is ownership, sustainability and continuity to ensure diverse groups of farmers have access to clean and affordable cassava seed. More detailed information on the conclusions, bottlenecks and recommendations can be found in Section 4

EFFECT OF MAIZE INTERCROP PLANT DENSITIES ON YIELD AND \u3b2-CAROTENE CONTENTS OF ORANGE-FLESHED SWEETPOTATOES

Despite efforts to demonstrate the value of orange-fleshed sweetpotato (OFSP) ( Ipomoea batatas L.) and quality protein maize ( Zea mays L.) in combating vitamin A and protein malnutrition, small land holdings by rural poor farmers still limit the crops\u2019 overall production in Africa. As such, intercropping and optimum plant density in cropping systems will help farmers to improve productivity of the crop, and hence, improve household food and nutrition security. This study determined the effect of maize plant population, in a sweetpotato-maize intercrop, on yields and \u3b2-carotene content of two popular OFSP cultivars, Ejumula and NASPOT 9 O (Kabode). Each variety was intercropped with maize variety Longe 5, at three plant densities (i.e. 41,666, 55,555 and 88,888 plants ha-1), at Ngetta Zonal Agricultural Research and Development Institute in Uganda. While 55,555 plants of each OFSP cultivar were used for both sole and intercrops, the sole maize plot was 44,444 plants ha-1. Maize and sweetpotato were harvested at 120 and 135 days after planting, respectively. \u3b2-carotene content and yield in sweetpotato roots were significantly (P<0.05) reduced by high maize density. Irrespective of maize density, NASPOT 9 O produced more root yields than Ejumula. Land Equivalent Ratios of >1.2 were obtained at maize intercrop densities of 41,666 and 55,555 plants ha-1.Malgr\ue9 les efforts visant \ue0 d\ue9montrer la valeur nutritionnelle en combinaison de la patate douce \ue0 chaire orange (OFSP) ( Ipomoea batatas L.) et du ma\uefs \ue0 grande valeur proteique ( Zea mays L.) dans la lutte contre la malnutrition li\ue9e au manque de la vitamine A et de proteine, les petits producteurs Africains continuent de limiter les rendements de leur cultures. A cet effet, l\u2019association des cultures doubl\ue9e d\u2019une densit\ue9 optimale des plants dans les systems de cultures, aiderait les producteurs \ue0 am\ue9liorer les rendements de leurs cultures et par consequent am\ue9liorer la qualit\ue9 de vie dans les m\ue9nages et assurer la s\ue9curit\ue9 alimentaire. La pr\ue9sente \ue9tude a d\ue9t\ue9rmin\ue9 l\u2019effet de la densit\ue9 des plants de ma\uefs, dans une culture associ\ue9e avec la patate douce sur le rendements et la teneur en \u3b2-carotene de deux vari\ue9t\ue9s populaires de patate douce OFSP, Ejumula et NASPOT 9 O (Kabode). Chaque vari\ue9t\ue9 a \ue9t\ue9 plant\ue9e en association avec la vari\ue9t\ue9 de ma\uefs Longe 5, \ue0 trois diff\ue9rentes densit\ue9s (i.e. 41,666, 55,555 et 88,888 plants ha-1), et ceci \ue0 l\u2019Institut Zonale de Developpement et de Recherche en Agriculture de Ngetta en Ouganda. Pendant que la densit\ue9 55,555 plants de chaque vari\ue9t\ue9 de OFSP a \ue9t\ue9 utilis\ue9 dans la culture solitaire et en association, la culture solitaire de ma\uefs \ue9tait \ue0 44,444 plants ha-1. Ma\uefs et patate douce ont \ue9t\ue9 r\ue9colt\ue9s respectivement \ue0 120 et 135 jours apr\ue8s. La teneur en \u3b2-carotene et le rendement en tubercules de patate douce ont \ue9t\ue9 r\ue9duits de fa\ue7on significative (P<0.05) par une densit\ue9 forte de ma\uefs. Quelle que soit la densit\ue9 de ma\uefs, NASPOT 9 O a produit plus de tubercules qu\u2019Ejumula. Le ratio \ue9quivalent \ue9tait >1.2 pour une densit\ue9 de ma\uefs de 41,666 et 55,555 plants ha-1, en culture d\u2019association

Sweetpotato selection releases: Lessons learnt from Uganda

The National Sweetpotato Programme of the National Agricultural Research Organisation (NARO) in Uganda released 14 sweetpotato cultivars between 1994 and 2005. Of the released cultivars, six have gained importance in local Ugandan markets and in export trade to Europe and two are being used as parental sources for high drymatter (>30%), sweetpotato virus disease (SPVD) and nematode resistance in hybridization schemes, and in the genetic mapping work in joint international collaborative research. Two orange-fleshed sweetpotato (OFSP) cultivars, namely, Ejumula, and SPK004 (Kakamega), high in beta-carotene (the precursor for vitamin A) arespreading rapidly for combating widespread vitamin A deficiency in Uganda. The major steps leading to the release of Kakemega and Ejumula are used to illustrate the experience of the Ugandan sweetpotato breeding programme sustained activities for a decade, and lessons learnt are highlighted. The sustained breeding activitieshave led to a vibrant and robust program, increased international and south to south collaboration, increased partnership and alliances; shifted research focus from production to production per se and quality (nutrition), resulting into significant and relevant agricultural research. The lesson here is that it takes a long time to develop technologies, disseminate and commercialize them. It also requires commitment by the donor, government, scientists, farmers and other stakeholders for effective commercialization of the developed technologies

Characterizing cassava farmer typologies and their seed sourcing practices to explore opportunities for economically sustainable seed business models in Rwanda

Open Access Article; Published online: 30 Nov 2021The overdependency on local cassava varieties and informal seed sources by farmers in Rwanda has contributed to the spread of cassava viral diseases. The use of improved planting materials made available through formal seed sources, that assure seed quality, is one way to prevent future disease outbreaks. In order to increase the availability of, and farmers access to, such materials there is increasing interest to develop seed business models. This study aims to understand seed sourcing practices of different farm typologies to inform the development of tailored seed business models. A total of 390 farmers were interviewed and the collected data was analyzed into clusters, resulting in seven farm typologies. Seed sourcing strategies, seed replacement dynamics and purchasing behavior of these typologies were explored via a seed tracing study. We find that more commercial oriented farmers have better access to formal seed sources. Nevertheless, the majority of farmers in all typologies accessed new varieties and quality cassava seed via informal channels. At both formal and informal sources, cash investments in seed were mainly made by the categories of better-off farmers, and were one-time investments to acquire a new variety. Based on farmers current seed sourcing practices, clarifications on the differences between farmers and their willingness-to-pay, the roles of seed degeneration, cost-benefit analysis, value propositions and profit formulas seem important requirements for the further development of viable cassava seed business models. We conclude that tailoring seed business models can have a high potential as it acknowledges differences among farmers, but that careful coordination is needed to ensure that one approach or intervention does not contrast with and/or undermine the others

Genetic diversity of local and introduced cassava germplasm in Burundi using DArTseq molecular analyses

Open Access Journal; Published online: 24 Jan 2022In Burundi most small-scale farmers still grow traditional cassava landraces that are adapted to local conditions and have been selected for consumer preferred attributes. They tend to be susceptible, in varying degrees, to devastating cassava viral diseases such as Cassava Brown Streak Disease (CBSD) and Cassava Mosaic Disease (CMD) with annual production losses of US$1 billion. For long term resistance to the disease, several breeding strategies have been proposed. A sound basis for a breeding program is to understand the genetic diversity of both landraces and elite introduced breeding cultivars. This will also assist in efforts to conserve landraces ahead of the broad distribution of improved varieties which have the possibility of replacing landraces. Our study aimed at determining the genetic diversity and relationships within and between local landraces and introduced elite germplasm using morphological and single nucleotide polymorphism (SNP) markers. A total of 118 cultivars were characterized for morphological trait variation based on leaf, stem and root traits, and genetic variation using SNP markers. Results of morphological characterization based on Ward’s Method revealed three main clusters and five accessions sharing similar characteristics. Molecular characterization identified over 18,000 SNPs and six main clusters and three pairs of duplicates which should be pooled together as one cultivar to avoid redundancy. Results of population genetic analysis showed low genetic distance between populations and between local landraces and elite germplasm. Accessions that shared similar morphological traits were divergent at the molecular level indicating that clustering using morphological traits was inconsistent. Despite the variabilities found within the collection, it was observed that cassava germplasm in Burundi have a narrow genetic base

Genetic variability and gain for storage root yield and yield components in yam beans

There is limited information on the genetic parameters and genetic gain of yam bean ( Pachyrhizus species) accessions introduced to Rwanda. No comprehensive literature exists on the inheritance of yield and yield components, on segregating populations. This study investigated variability, heritability and genetic advance in F2 yam bean genotypes. Seven F2 yam bean hybrids were evaluated at the Rubona Research Station located in Southern Province of Rwanda, during growing season 2014B. Results revealed significant (P<0.01) genetic variability in plant vigour (PV), pod weight (WOP), plant height (PHT), 100 seed weight (100SW), total biomass yield (TBY), storage root yield (SRY), dry matter content (DMC), and starch content (STA). High genetic (\u3c32g) and phenotypic (\u3c32p) variances, and genotypic coefficients of variation (GCV> 25%) were observed for WOP, PHT, 100SW, TBY, DMC and STA. Estimates of heritability (H2) were high (greater than 50%) for all traits, except for seed yield, number of roots and number of pods. The GA and genetic advance, as percentage of the mean (GAM%), were high for PV, WOP, PHT, 100SW, TBY and DMC. There were positive and significant (P<0.05) associations between PV and PHT, protein content (PRO), 100SW, TBY, SRY, and DMC. Dry matter content also had positive and significant (P<0.01) correlations with STA. These results indicate presence of high genetic variability, heritability and expected genetic gain suggesting potential for genetic improvement of plant vigour, weight of pods, plant height, 100 seed weight, total biomass yield, storage root fresh yield, dry matter content and starch content of yam beans in Rwanda.Il existe peu d\u2019informations sur les param\ue8tres g\ue9n\ue9tiques et le gain g\ue9n\ue9tique des accessions de haricot-igname (esp\ue8ce Pachyrhizus ) introduites au Rwanda. Il n\u2019existe pas de litt\ue9rature compl\ue8te sur l\u2019h\ue9r\ue9dit\ue9 du rendement et des composantes du rendement, sur la s\ue9gr\ue9gation des populations. Cette \ue9tude a \ue9tudi\ue9 la variabilit\ue9, l\u2019h\ue9ritabilit\ue9 et l\u2019avanc\ue9e g\ue9n\ue9tique des g\ue9notypes de haricot-igname F2. Sept hybrides de haricot-igname F2 ont \ue9t\ue9 \ue9valu\ue9s \ue0 la Station de Recherche de Rubona situ\ue9e dans la Province M\ue9ridionale du Rwanda, pendant la saison agricole 2014B. Les r\ue9sultats ont r\ue9v\ue9l\ue9 une variabilit\ue9 g\ue9n\ue9tique significative (P <0,01) de la vigueur de la plante (PV), du poids de la gousse (WOP), de la hauteur de la plante (PHT), du poids de 100 graines (100SW), du rendement total en biomasse (TBY), du rendement des racines de stockage (SRY), teneur en mati\ue8re s\ue8che (DMC) et teneur en amidon (STA). Des variances g\ue9n\ue9tiques (\u3c32g) et ph\ue9notypiques (\u3c32p) \ue9lev\ue9es et des coefficients de variation g\ue9notypiques (GCV> 25%) ont \ue9t\ue9 observ\ue9s pour WOP, PHT, 100SW, TBY, DMC et STA. Les estimations de l\u2019h\ue9ritabilit\ue9 (H2) \ue9taient \ue9lev\ue9es (sup\ue9rieures \ue0 50%) pour tous les caract\ue8res, \ue0 l\u2019exception du rendement en graines, du nombre de racines et du nombre de gousses. Le GA et l\u2019avance g\ue9n\ue9tique, en pourcentage de la moyenne (GAM%), \ue9taient \ue9lev\ue9s pour PV, WOP, PHT, 100SW, TBY et DMC. Il y avait des associations positives et significatives (P <0,05) entre PV et PHT, la teneur en prot\ue9ines (PRO), 100SW, TBY, SRY et DMC. La teneur en mati\ue8re s\ue8che avait \ue9galement des corr\ue9lations positives et significatives (P <0,01) avec le STA. Ces r\ue9sultats indiquent la pr\ue9sence d\u2019une variabilit\ue9 g\ue9n\ue9tique, d\u2019une h\ue9ritabilit\ue9 et d\u2019un gain g\ue9n\ue9tique attendus \ue9lev\ue9s sugg\ue9rant un potentiel d\u2019am\ue9lioration g\ue9n\ue9tique de la vigueur des plantes, du poids des gousses, de la hauteur des plantes, du poids de 100 graines, du rendement total en biomasse, du rendement en racines fra\ueeches de stockage, de la teneur en mati\ue8re s\ue8che et en amidon de haricot-ignames au Rwanda

HERITABILITY, COMBINING ABILITY AND INHERITANCE OF STORAGE ROOT DRY MATTER IN YAM BEANS

Storage root dry matter content (RDM) is central to the improvement of consumer and industrial attributes of root crops. Yam bean ( Pachyrhizus species) is a legume root crop newly introduced in Uganda, but its adoption may be constrained by low RDM. The objective of this study was to investigate the magnitude of variance for general combining ability (GCA) and specific combining ability (SCA) effects, heritability estimates and inheritance of RDM in yam beans. Progenies of sixteen crosses, generated using the North Carolina (NCII) mating scheme, were evaluated in F1 and F2 field experiments, with three replications at the National Crops Resources Research Institute (NaCRRI), Namulonge in Central Uganda, during the first cropping seasons of April, 2013 and 2014, respectively. Significant (p<0.001) mean squares for general combining ability (GCA), and specific combining ability (SCA) were observed in F1 and F2 generations, demonstrating additive and non-additive genetic inheritance of RDM. High Baker\u2019s ratio in F1 (0.76) and F2 (0.78), and large \u3c32GCA/ \u3c32SCA (3.13) indicate predominance of additive gene effects. Narrow sense heritability was high in both F1 (0.74) and F2 (0.75), implying that RDM can be improved in yam beans through selection. The results provide a basis for selection of suitable parents for hybridisation and breeding programmes to develop high dry matter yam bean varieties in Uganda.La teneur en mati\ue8res \ue8che du stock racinaire (MSR) est essentiel en terme d\u2019am\ue9lioration des qualit\ue9s des cultures racinaires pour les consommateurs et d\u2019industriels. Le haricot-igname (esp\ue8ce Pachyrhizus ) est une culture racinaire l\ue9gumineuse nouvellement introduite en Ouganda, mais son adoption pourrait \ueatre handicap\ue9e par sateneur basse en mati\ue8res \ue8che racinaire. Cette \ue9tude avait pour objectif d\u2019\ue9tudier le niveau de la variance pour les effets de la capacit\ue9 de combinaison g\ue9n\ue9rale et la capacit\ue9 de combinaison sp\ue9cifique, estimations de l\u2019h\ue9ritabilit\ue9 et l\u2019h\ue9ritage de MSR dans les haricots ignames. Les prog\ue9nies de seize croisements g\ue9n\ue9r\ue9s \ue0 l\u2019aide du syst\ue8me de croisement de la Caroline du Nord (NCII), ont \ue9t\ue9 \ue9valu\ue9s dans des essais en champs de F1 et F2 avec trois r\ue9p\ue9titions \ue0 l\u2019Institut National de Recherche sur les Ressources V\ue9g\ue9tales (NaCRRI), Namulonge en Ouganda, pendant les premi\ue8res saisons culturalesd\u2019 Avril 2013 et 2014, respectivement. Les carr\ue9s moyens significatifs (P<0,001) de capacit\ue9 g\ue9n\ue9ralede combinaison et capacit\ue9 sp\ue9cifique de combinaison \ue9taient observ\ue9s dans les g\ue9n\ue9rations F1 et F2 d\ue9montrant ainsi un heritage g\ue9n\ue9tique additif et non additive de MSR. Le rapport \ue9lev\ue9 de Baker en F1 (0,76) et F2 (0,78), et \u3c32GCA/ \u3c32SCA (3.13) large indiquent la pr\ue9dominance des effets de g\ue8nes additifs. Une \ue9troite h\ue9ritabilit\ue9 d\u2019ordre de F1 (0.74) et F2 (0.75) \ue9tait observ\ue9e, ce qui implique que MSR peut \ueatre am\ue9lior\ue9 dans le haricot-igname par voie de s\ue9lection. Les r\ue9sultats constituent une base pour la s\ue9lection des parents appropri\ue9s pour les programmes d\u2019hybridation et d\u2019am\ue9lioration g\ue9n\ue9tique pour d\ue9velopper des vari\ue9t\ue9s de haricot-ignames \ue0 haute teneur en mati\ue8res\ue8 che en Ouganda

Genotype by environment cultivar evaluation for cassava brown streak disease resistance in Tanzania

Open Access Article; Published online: 24 May 2020Cassava brown steak disease (CBSD), caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), is the most important biotic constraint to cassava production in East and Central Africa. Concerted efforts are required to prevent further spread into West Africa as well as to reduce losses in areas already affected. The study reported here was part of a five-country (Kenya, Malawi, Mozambique, Tanzania and Uganda) programme that aimed to identify superior cassava cultivars resistant to CBSD and to disseminate them widely in the region. Seventeen tissue-cultured and virus-tested cultivars were evaluated in Tanzania across nine sites with diverse CBSD inoculum conditions. Experiments were planted using an alpha-lattice design and assessments were made of surrounding inoculum pressure, CBSD foliar and root incidence and root yield at harvest. There were large differences in CBSD infection between sites, with greatest spread recorded from the north-western Lake (Victoria) zone. Differences were driven by Bemisia tabaci whitefly vector abundance and CBSD inoculum pressure. Both CBSV and UCBSV were almost equally represented in cassava fields surrounding experimental plots, although CBSV predominated in the north-west whilst UCBSV was more frequent in coastal and southern sites. However, the incidence of CBSV was much greater than that of UCBSV in initially virus-free experimental plots, suggesting that CBSV is more virulent. Cultivars could be categorised into three groups based on the degree of CBSD symptom expression in shoots and roots. The seven cultivars (F10_30R2, Eyope, Mkumba, Mkuranga1, Narocass1, Nase3 and Orera) in the most resistant category each had shoot and root incidences of less than 20%. Fresh root yield differed between sites and cultivars, but there was no genotype by environment interaction for this trait, probably attributable to the large fertility and soil moisture differences between sites. Susceptible cultivars and the local check performed well in the absence of CBSD pressure, highlighting the importance of exploiting quality and yield traits of local landraces in breeding programmes. Overall, our results emphasized the importance of applying a balanced strategy for CBSD management. This should use both improved and local germplasm resources to generate high yielding cultivars for specific end-user traits, and combine the deployment of improved cultivars with phytosanitary control measures including the use of healthy planting material and planting during periods of reduced CBSD infection