Evaluation of performance of introduced yam bean (Pachyrhizus spp.) in Rwanda.

Root and tubers crops are key staple crops for both rural and urban populations in Rwanda and supporting more than nine million people living in densely populated areas and sustained on agriculture with diverse range of cultivated species. Yam bean (Pachyrizhus spp) was introduced for both its immediate utilization as a high-yielding root crop with high sugar, considerable micronutrient concentrations and protein content for subtropical regions compared to common grown tropical root and tuber crops (cassava, potato, sweetpotato and yam).The yields of these species are up to 100 tons fresh weight per hectare, with dry matter contents of up to 25%. Recent introduction of different yam bean accessions in different agro-ecological zones of Rwanda produced high yield storage roots. Higher storage roots yield with strict pruning was produced by Erosus genotype 209018 (111.33 t/ha) and genotype 209019 (108.00 t/ha) followed by Ahipa genotype 209029 with 76.33 t/ha respectively. Dry matter was relatively low with a range of 20.84-19.14 % for all introduced genotypes. As a root crop with capacity of fixing atmospheric nitrogen and which does not require good-quality soil and resists pests and diseases which can fix yields abundantly and produces well even in area with scanty rain, it might be well indicated for Rwand

What is the consumers' perception of bakery products made with vitamin A rich sweetpotato and wheat?

Manufacturers who import agricultural commodities like wheat are facing increasing costs due to rising commodity prices. Sweetpotato can replace up to 40% of the wheat in many bakery products. This can lower firm production costs, save a country foreign exchange, and increase rural farmers' incomes. We produced bread, biscuits, queen cakes and doughnuts in a commercial bakery, using different combinations of ingredients as follows: wheat flour only; a mixture of wheat flour and orange-flesh sweetpotato (OFSP) flour; and, a mixture of wheat flour and OFSP puree. The products were then subjected to sensory testing, using 120 consumer panelists drawn from a rural primary school, an urban girls' secondary school, and a university. Each of the testers was given a sample of each product marked with a circle, diamond, or square. We used means t-tests and ordered-logit to analyze the evaluations. The results showed that bread made out of a mix of 30% OFSP puree and 70% wheat flour was preferred to that made of 100% wheat flour. Consumers showed no preference between doughnuts and queen cakes made from 100% wheat flour and those made from a mix of 60% wheat flour and 40% OFSP puree. Biscuits made of 40% OFSP puree mixed with 60% wheat flour were preferred to those made with 100% wheat flour. Therefore, sweetpotato puree can be a good substitute of some percentage of wheat for the analyzed products, helping to bring down production costs and food price

Improving farmers' access to clean planting material through partnership in the value chain.

Sweetpotato is an important food security crop in Rwanda grown mainly by women for household consumption and as a source of family income Sweetpotato production is faced with several constraints, among them the availability of clean planting of most varieties but more so of the new Vitamin A richOrange Fleshed Sweetpotato. This is limiting their potential to benefits producers, processors, and consumers as a source of food based vitamin A. Therefore an efficient sustainable seed system for multiplication and distribution of cleaning planting material to users is vital. Through a thorough need assessment, four districts were identified for OFSP promotion. Farmer based approach was used to develop an effective, rapid and sustainable chain for multiplication and to disseminate clean basic sweetpotato planting material from in vitro lab to subsequent multiplication sites. Public, research, private, development organization, and farmer group's partnership was paramount to clean, multiply, identify, organize and train farmers' groups in different modules. Most of the new varieties namely, Cacearpedo, Gihingamukungu, and Ukerewe possess preferred traits by farmers compared to their local ones. Now farmers know the importance of using clean planting cuttings as a factor to increase productivity when planted at right time. Initial comparison of harvest from two consecutive seasons, May to July 2011 and July to December 2011 the study finds an increase of yield of 27% for Cacearpedo, 22% for Ukerewe and 71% for 97-062. This can be attributed to improved technical support, adoption of better agriculture techniques, healthy vines, and on time vines availability

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

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

Evaluation of performance of introduced yam bean (Pachyrhizus spp.) in three agro-ecological zones of Rwanda

Article purchased; Published online: 25 May 2017The yam bean (Pachyrizhus spp) was recently introduced as a root crop with high-yield potential, considerable protein and micro-nutrient concentration to investigate its potential for food production in Rwanda. Except for Chuin types (Pachyrizhus tuberosus) which have high storage root dry matter (RDM) (26 to 36%), most accessions are consumed raw and are reported to have low RDM. The present study aimed to evaluate and identify adapted high yielding yam bean accessions in major agro-ecological zones of Rwanda. Field experiments with 22 accessions were conducted in 2012 at three research sites representing the major agro-ecologies of Rwanda. Strict reproductive pruning was followed to enhance fresh storage root yields. Across locations, ANOVA indicated highly significant differences (p < 0.01) for genotypes (G), locations (L), seasons (S) and G x L effects for storage root yield, vine yield and harvest index and accounted for 21.88%, 43.41%, 1.43% and 13.25% of the treatment sum of squares, respectively. The GGE bi-plot revealed that EC209018 is high yielding but unstable. However, genotypes, AC209034, AC209035 and EC209046, were outstanding in terms of adaptation and relative stability across the 3 locations, suggesting consistent root yields irrespective of location and environmental conditions. The GGE scatter plot showed that all genotypes formed one mega-environment for storage root yield (Karama, Musanze and Rubona) and two mega-environments for biomass yield (Karama and Rubona as one mega-environment and Musanze the second one). This study revealed that Karama is the most suitable environment for evaluation and selection of yam bean for yield components in Rwanda

Genetic variation and response to selection for storage root dry matter and associated traits in a population of yam bean (Pachyrhizus spp.) interspecies crosses

The goal of yam bean improvement in Africa is to develop superior high yielding and high dry matter cultivars that are preferred for adoption. In this study, the estimates of variance components, heritability and response to selection were studied in F3 yam bean families selected from interspecies crosses targeting improvement of storage root dry matter and associated traits. Breeding populations were generated using North Carolina II (NC II) mating design involving high dry matter P. tuberosus chuin cultivar, low dry matter P. ahipa and the high yielding P. erosus yam beans. The progenies were advanced through selfing from F1 to F2 population and then exposed to selection at 10% selection intensity to obtain 83 high dry matter lines. The selected lines were evaluated in an F3 trial using a randomized complete block design (RCBD) with three replications at the National Crops Resources Research Institute (NaCRRI) Namulonge, in Central Uganda. The results revealed significant (P < 0.001) genetic variation for storage root dry matter (RDM), storage root fresh yield (RFY), storage root dry yield (RDY), vine yield (VNY), fresh biomass yield (FBY), harvest index (HI), starch (STA) and protein (PRO) content. High genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were obtained for VNY, RDY, FBY, RFY, RDM and STA. Narrow sense heritability was higher than 0.5 and response to selection was 15.5 to 33.1 for RDM, RFY, RDY, VNY, FBY and STA, indicating rapid genetic progress is achievable and early generation selection would be effective to improve these traits. Significant (P < 0.01) positive genetic correlations were observed between RDM, RDY, RFY, VNY, FBY and STA ranging from 0.422 to 0.963 implying that simultaneous improvement of these traits is possible in the current yam bean populations