HORTSCIENCE 49(10):1349–1352. 2014. ‘RW11-17’, ‘RW11-1860’, ‘RW11-2419’, ‘RW11-2560’, ‘RW11-2910’, and ‘RW11-4923’ Sweetpotato Damien Shumbusha, Jean Ndirigwe, Lydia Kankundiye, Anastasie Musabyemungu, Daphrose Gahakwa, and Phanuel S. Ndayemeye Rwanda Agriculture Board (RAB), P.O. Box 5016, Kigali, Rwanda Robert O.M. Mwanga1 International Potato Center (CIP), Box 22274, Naguru Hill, Ntinda II Road, Plot 47, Kampala, Uganda Additional index words. Alternaria bataticola blight, dry matter yield, dual-purpose, Ipomoea batatas, sweetpotato virus disease zones of Rwanda (Table 1). All the 60 parents were used in the polycross as sources of one or a combination of genes controlling important desirable traits. During the evaluation, the six clones were coded as follows: abbreviation for Rwanda, the last two digits of the year (2011) the genotype was initially selected (11), and the genotype selection number. The codes of these cultivars became the official names at cultivar release. All the six cultivars were respectively, the progenies of the following female parents: ‘Ejumula’, an OFSP landrace introduced from Uganda; ‘2000-203’, a RAB breeding line; ’97-062’, also, known as Gihingamukungu, orange-fleshed, released in 2004; ‘Mugande’, bred and released by RAB in 2004; ‘SPK004’, an OFSP landrace introduced from Kenya; and ‘Ukerewe’, a yellow-fleshed cultivar from Tanzania. Description and Performance Six dual-purpose sweetpotato [Ipomoea batatas L. (Lam.)] cultivars, RW1117, RW111860, RW112419, RW112560, RW112910, and RW114923, were approved for release by the Plant Variety Release Committee of Rwanda in Feb. 2013 (RAB, Rwanda Agriculture Board, 2013). Sweetpotato forms a major part of the diet of both rural and urban communities in Rwanda. Moreover, the crop is expected to become more important with time as farmers engaged in mixed crop–livestock systems increasingly use vines as animal feed. Its use for both food and feed makes it attractive in areas where land availability is a constraint. Moreover, the implementation of the Rwandese government policy, which encourages use of zero grazing practice to mitigate soil erosion, emphasizes the use of sweetpotato as an alternative source of animal forage (MINAGRI, 2013). The six released cultivars have relatively high dry matter content (30%) and have good to high consumer acceptance. The cultivars also have moderate to high levels of field resistance to sweetpotato virus disease (SPVD) and Alternaria bataticola blight and yield higher (8.3 to 22.8 t·ha–1) than the average storage root yield of 6.0 t·ha–1 [FAOSTAT, 2011; International Potato Center (CIP), 1999]. Two of the released cultivars, RW11-2910 and RW11-2560, are orange-fleshed sweetpotato (OFSP), providing consumers with moderate to high beta-carotene (provitamin A) with potential to alleviate vitamin A deficiency. Thus, the official release of these dual-purpose sweetpotato cultivars for both food and animal feed, developed through on-station evaluation and farmer participatory selection, to augment the food and farming systems in Rwanda is reported. Received for publication 2 June 2014. Accepted for publication 19 Aug. 2014. This work was supported, in part, by a grant from the Alliance for a Green Revolution in Africa (AGRA), through a breeding project, grant reference 2009 PASS 028. 1 To whom reprint requests should be addressed; e-mail r.mwanga@cgiar.org; rmwanga7@gmail.com. HORTSCIENCE VOL. 49(10) OCTOBER 2014 Origin The six sweetpotato cultivars, RW11-17, RW11-1860, RW11-2419, RW11-2560, RW11-2910, and RW11-4923, are field seedling selections from the sweetpotato program of the Rwanda Agriculture Board (RAB, Rwanda Agriculture Board, 2013). The cultivars were selected from bulked seed from an open-pollinated polycross nursery of 60 parents established in 2010; their male pedigrees are unknown. The 60 parents in the polycross comprised 30 introductions and 30 landraces collected from different major agroecological The International Potato Center (CIP), Asian Vegetable Research and Development Center, and International Board for Plant Genetic Resources (1991) descriptors were used to describe the six sweetpotato cultivars released in Rwanda (Table 2). ‘RW11-17’, ‘RW11-1860’, ‘RW11-2910’, and ‘RW11-4923’ are spreading, whereas ‘RW11-2560’ and ‘RW11-2910’ are semierect with either short or very short internodes. Apart from ‘RW11-2910’ and ‘RW11-2910’, which have vines that are predominantly green with purple pigmentation, the others have green vines. Mature leaf shape is triangular in ‘RW11-17’ and ‘RW11-2419’, Table 1. Origin and main attributes of sweetpotato parents used in the 2009–10 polycross nursery at Rubona, Rwanda.z Serial no./ Skin Flesh Serial no./ Skin Flesh cultivar name Origin color color cultivar name Origin color color 1 2000-040 IB Red O 31 NASPOT 8 NU PR O 2 2000-203 IB White W 32 Silik Omuyaka NU C W 3 2000-179 IB Red W 33 Otada NU C C 4 2000-024 IB Red Y 34 Porosita CN PR C 5 6-468 I Red W 35 Tedolokeren NU C C 6 Mugande I Red W 36 Dimbuka NU C C 7 Karebe I Red W 37 Kyabafuruki NU C W 8 2002-154 I Red W 38 New Kawogo NU PR W 9 440034 CN White O 39 NASPOT 10 NU PR DO 10 440164 CN Red W 40 SPK00/6/6-1 NU PR DO 11 8-1038 I Red W 41 LUW1274 NU C O 12 Kwezikumwe I Yellow Y 42 Zapallo CN C O 13 SPK-004 CN Red LO 43 Magabari NU C C 14 Cacearpedo I Yellow O 44 Bunduguza NU PR DO 15 Chair orange I Red P 45 Carrot C CN C DO 16 Naspot A NU White W 46 Tanzania NU C LY 17 Ukerewe CN Red O 47 Nsasagatebo IB R C 18 Mayai CN Red O 48 NASPOT 2 NU PR C 19 Carrote CN Red O 49 NASPOT 3 NU C C 20 Zambezi CN White O 50 NASPOT 6 NU C W 21 Naspot 1 NU White Y 51 Rushakashaka NU R W 22 Ejumula NU Cream O 52 Rukocoka I R C 23 2005-179 NU White W 53 44-0165 I R W 24 Gihingamukungu L Red W 54 Rwaserinda I R W 25 Seruruseke I Red Y 55 Gishefu I R W 26 Anyumeli NU O C 56 Giteke I W W 27 Calomex CN C O 57 Melesiyana I W W 28 Araka white NU C W 58 Saturisi I R W 29 Luw NU R C 59 Rwabakungu I R W 30 KM161 NU W W 60 Nyiragasimbuka I W W z Codes used in table—origin: IB = ISAR bred; I = ISAR; CN = CIP/Nairobi; NU = NARO/Uganda; L = landrace; skin color: C = cream; LY = light yellow; DO = dark orange; PR = purple–red; flesh color: O = orange; W = white; Y = yellow; LO = light orange; P = purple; LY = light yellow; DO = dark orange. 1349 Table 2. Morphological descriptors of seven sweetpotato cultivars released in Rwanda in Feb. 2013.z Descriptor RW11-17 Plant type Spreading Spreading Length Diameter Short Very thin Short Intermediate Predominant color Secondary color Green Green with purple Green with purple Dark purple Cultivar RW11-2560 Plant type Semi-erect Semi-erect Vine internode Short Short Very thin Thin Vine pigmentation Green Green RW11-1860 RW11-2419 Green Triangular Very slight 1 Triangular Green Mature leaf shape Lobed Deep 5 Hastate General outline Lobe type Lobe number Shape of central lobe Triangular Very slight 1 Triangular Hestate Moderate 3 Triangular Mature leaf Purple Green Abaxial leaf vein Immature leaf Petiole pigmentation Purple Green Green Purple Green Green Foliage color Green with purple Green veins Green with purple Green edge Green Green Green Green Habit Stigma exertion Sparse Exerted Sparse Slightly exerted None Exerted Seed set Sparse Profuse Stalk Formation Shape Short Dispersed Long elliptical Surface defects Alligator like skin Short Dispersed Long irregular or curved Veins Flowering Sparse Sparse Capsule Sparse Sparse Storage root Intermediate Short Very dispersed Closed cluster Long elliptical Long elliptical Alligator like skin Skin color Predominant Red White White Cream Intensity Dark Dark Dark Intermediate Secondary Absent Cream Absent Absent Flesh color Predominant Cream Pale yellow White Deep orange Secondary Yellow Cream Absent Absent z Selected descriptors according to International Potato Center, Asian Vegetable Research and Genetic Resources (1991). hestate in ‘RW11-1860’ and ‘RW11-2910’, or lobed in ‘RW11-2910’ and ‘RW11-4923’. Flowering is sparse in all the cultivars, whereas seed set is sparse in ‘RW11-17’, ‘RW11-2419’, and ‘RW11-2560’; moderate in ‘RW11-2910’ and ‘RW11-4923, but profuse in ‘RW11-1860’. The skin color of the storage root is red in ‘RW11-17’ and ‘RW11-2910’, white in ‘RW11-1860’ and ‘RW11-2419’, cream in ‘RW11-2560’, and purple–red in ‘RW11-4923’. Their flesh color is white in ‘RW11-2419’, pale yellow in ‘RW11-1860’, light orange in ‘RW11-2560’, intermediate orange in ‘RW11-4923’, and deep orange in ‘RW11-2910’. Dual-purpose sweetpotato cultivars were developed through farmer participatory selection using the accelerated breeding scheme (Gr€uneberg et al., 2009). A total of 8000 true seeds from the polycross described in the subsection, origin, were scarified in concentrated sulfuric acid, germinated in a screenhouse, and vine cuttings from the seedlings were used to establish a seedling nursery at Rubona in Rwanda. In total, 5380 well-established genotypes were selected 1350 Alligator-like skin RW11-2910 RW11-4923 Kwezikumwe Spreading Spreading Semi-erect Short Very thin Very short Very thin Very short Very thin Green with purple Green Green Green with purple Purple tip Absent Hestate Moderate 3 Triangular Lobed Deep 5 Hastate Lobed Deep 5 Hastate Green Green Green Purple Green Green Green Slightly purple Green Green Green Green Sparse Exerted Sparse Exerted Profuse Inserted Moderate Moderate Moderate Short Closed cluster Long elliptical Short Dispersed Long oblong Short Open cluster Long elliptical longitudinal grooves Alligator-like skin Alligator-like skin Red Dark Purple–red Purple–red Intermediate Red Cream Intermediate Absent Light orange Intermediate orange Cream Absent Yellow Absent Development Center, and the International Board for Plant from the seedling nursery. Five vine cuttings of each genotype were planted on ridges 0.8 m apart and 0.3 m between plants in an observation trial at Rubona, Karama, and Ngoma in a randomized complete block design with two replications during the 2011B season (second rainy season). The six released cultivars were evaluated for four seasons from 2011 to 2013 on-station at Rubona, Karama, and Ngoma in three major agroecologies, which are the major sweetpotato-producing areas of Rwanda. Rubona is in the midaltitude agroecology, 1650 m above sea level (masl), characterized by low SPVD pressure. Karama is in the low-altitude zone, 1420 masl, characterized by moderate to high SPVD pressure, whereas Ngoma is in the semiarid agroecological zone, 1400 masl, characterized by medium SPVD pressure (Ndirigwe, 2006; RAB, Rwanda Agriculture Board, 2000, 2013). Farmers selected promising clones in preliminary trials (two rows, 15 plants, two replications, 2012A season, the first rainy season), advanced trial (four rows, 17 plants, two replications, 2012B season), national performance trial (four rows, 17 plants, two replications, 2013A), and on-farm trials (14 farmers in each of three major agroecologies, each farm was considered a replication, 2012B and 2013A season). The planting distance, 0.3 m · 0.8 m, was used in all trials except the seedling nursery. During evaluation, both SPVD and Alternaria bataticola blight were scored according to Gr€ uneberg et al. (2010) on a scale of 1 to 9, where 1 = no disease symptoms, 2 = unclear disease symptoms, 3 = clear disease symptoms at one plant per plot, 4 = clear disease symptoms at two to three plants per plot, 5 = clear disease symptoms at 5% to 10% of plants, 6 = clear disease symptoms at 10% to 25% of plants, 7 = clear disease symptoms at 25% to 50% of plants, 8 = clear disease symptoms at nearly all plant per plot, and 9 = clear disease symptoms with clearly reduced growth in all plants. Data were collected on storage root weight, marketable roots (root diameter greater than 25 mm), vine weight, and biomass. To assess dry matter (DM) of storage roots and vines, 200 g from each HORTSCIENCE VOL. 49(10) OCTOBER 2014 Table 3. Performance of the six sweetpotato released cultivars on-station across three locations, Rubona, Karama, and Ngoma in 2013A.z Storage root yield (t·ha–1) Vine yield SPVD Alternaria Cultivar blight Total Marketable (t·ha–1) RW11-17 21.9 14.5 31.6 1.3 1.0 RW11-1860 20.8 14.3 25.6 2.2 1.3 RW11-2419 20.7 15.1 31.5 2.8 1.3 RW11-2560 22.8 17.9 26.3 2.2 1.0 RW11-2910 20.0 13.1 28.2 2.5 2.0 RW11-4923 19.0 11.8 28.4 2.0 1.0 Kwezikumwe 14.1 11.3 30.6 1.7 1.0 Mean 19.9 14 28.9 2.4 1.3 LSD0.05 6.0 6.9 6.7 1.7 1.0 CV (%) 16.1 19.2 32.0 35.6 36.3 z Rubona, situated 2.59 S and 29.73 E is in the midaltitude agroecology, 1650 m above sea level (masl), with 1050 to 1200 mm rainfall, 18.7 C, low sweetpotato virus disease (SPVD) pressure, and light gravel soil texture; Karama, situated 1.94 S, 30.06 E is in the low-altitude, semiarid agroecology, 1400 masl, with 700 to 900 annual rainfall, 20.8 C mean annual temperature, high SPVD pressure, in the semiarid, drought-prone zone; Ngoma, situated 2.16 S, 30.55 E is in the low-altitude agroecology, 1420 masl, with 850 to 1000 mm rainfall, 20.3 C, medium SPVD pressure, and clay soil. LSD = least significant difference. in seven districts, namely, Huye, Nyamagabe, Ruhango, Muhanga in the southwest, Kamonyi in central, Bugesera in the south, and Ngoma in the southeast. Dissemination was mainly through farmer-to-farmer exchange or sale of planting material. Most seed companies do not disseminate sweetpotato planting material. Sweetpotato planting material reached farmers in the mentioned districts through RAB projects and various development partners such as Catholic Relief Services, Young Women Christian Association, the farmers’ federation (Imbaraga Syndicate), World Vision, and Africare. Availability The released cultivars are currently maintained in the open field of RAB at Rubona, Rwanda. Requests for planting material Table 4. Yield quality attributes and reaction to pests and diseases on-farm of six sweetpotato cultivars released in Rwanda in Feb. 2014. Local control Attribute RW11-17 RW11-1860 RW11-2419 RW11-2560 RW11-2910 RW11-4923 (Kwezikumwe) 12.9 9.8 11.8 13.4 8.3 9.1 6.9 Mean storage root (SR) yield (t·ha–1) Mean SR yield (% of local control) 186.9 142.0 171.0 194.2 120.4 131.8 100.0 Dry matter (DM) content of SR (%) 30.8 37.8 24.9 21.0 31.1 37.3 30.0 DM content (%) of vines 17.0 20.7 17.6 20.6 18.3 19.2 18.0 4.0 3.7 2.9 2.8 2.6 3.4 2.1 DM yield of roots (t·ha–1) 4.1 4.8 3.4 2.7 3.9 4.4 2.6 DM yield of vines (t·ha–1) Fresh weight root to vine ratio 2.0 1.9 1.9 2.0 2.0 2.0 2.1 Maturity (days) 135–150 120–135 135–150 120–135 120–135 135–150 120–135 Excellent Excellent Good Good Good Very good Very good Taste test rank (n = 32; 19 female, 13 male)z Field reaction to SPVDy MR MR MR MR MR MR MR Field reaction to Alternaria stem blight MR MR MR MR MR MR MR Field reaction to weevils MR MR MR MR MR MR MR z Taste test rank was based on aggregate pairwise comparison by the panel (farmers) evaluating taste, flavor, flesh color, skin color, and general acceptability. y SPVD = sweetpotato virus disease; MR = moderately resistant, moderate damage resulting from disease or moderate numbers of insects present or moderate damage (in case of insect damage). Classifications of the resistance were based on field evaluation in Rwanda. clone was oven-dried at 65 C to constant weight, and DM was computed as a percentage of the fresh weight. Selection of dual-purpose clones was based on the ratio of roots to vines in terms of dry matter yield, where a clone with a ratio of 1.5 to 2.0 was classified as dual purpose (Claessens et al., 2009). The data were analyzed using the GenStat 12th edition statistical software (GenStat, 2009). Following the accelerated breeding scheme of Gr€uneberg et al. (2009), the six released cultivars performed as well as the local control in on-station tests for marketable storage root yield, vine yield, SPVD, and Alternaria blight resistance. ‘RW11-2910’ and ‘RW11-4923’ had similar total and marketable storage root yields to the local control, whereas the other four cultivars had significantly higher storage root yields than the control (Table 3). Compared with the local control (‘Kwezikumwe’), cultivar RW11-2560 had higher mean total storage root yields across the three locations as well as in on-farm trials, 22.8 t·ha–1 and 13.4 t·ha–1, respectively (Tables 3 and 4) . Yields reported here are higher than yields reported by DONATA (2012), FAOSTAT (2011), and RAB, Rwanda Agriculture Board (2013) survey where the storage root yield average was 6 to 7 t·ha–1. Based on the field evaluations, the HORTSCIENCE VOL. 49(10) OCTOBER 2014 six released cultivars had a root-to-vine ratio more than 1.5 and therefore are suitable for dual-purpose use in the mixed farming systems of Rwanda. Apart from ‘RW11-2419’ and ‘RW11-2560’ with 24.9% and 21.0% DM, respectively, the other four cultivars had high storage root DM of greater than 30% (Table 4), fitting well with Rwandan starch and sugar level preferences in sweetpotato (Ndirigwe, 2006). Cultivars RW11-2560 and RW11-2910 are orange-fleshed with potential to contribute to reduction of vitamin A deficiency if consumed by the communities in Rwanda (DONATA, 2012). In general, all cultivars showed moderate resistance to SPVD, Alternaria stem blight, and sweetpotato weevil attack. Based on taste tests by a total of 32 farmers, aggregate pairwise comparison of taste, flavor, flesh color, skin color, and general acceptability, the farmers ranked ‘RW11-2419’, ‘RW11-2560’, and ‘RW11-2910’ as good; ‘RW11-4923’ and the local control, ‘Kwezikumwe’ as very good, whereas ‘RW11-17’ and ‘RW11-1860’ were ranked as excellent. Diffusion of Cultivars Of a total of 30 districts in Rwanda, the released cultivars have been disseminated should be addressed to: Sweetpotato Program, RAB, P.O. Box 5016 Kigali, Rwanda. Literature Cited Claessens, L., J.J. Stoolvogel, and J.M. Antle. 2009. Ex ante assessment of dual-purpose sweet potato in the crop-livestock systems of western Kenya: A minimum-data approach. Agric. Syst. 99:13–22. DONATA. 2012. Dissemination of new agriculture technology in Africa. Project report, Rwanda. FAOSTAT. 2011. Roots, tubers, sweetpotato production. Food and Agriculture Organization of the United Nations, Rome, Italy. Feb. 2014. <http://faostat.fao.org/site/339/default.aspx/>. GenStat. 2009. GenStat Release 12.1 for PC/ Windows XP. VSN International Ltd. Gr€uneberg, W.J., R. Eyzaguirre, J. Espinoza, R.O.M. Mwanga, M. Andrade, H. Dapaah, S. Tumwegamire, S. Agili, F.P. Ndingo-Chipungu, S. Attaluri, R. Kapinga, T. Nguyen, X. Kaiyung, K. Tjintokohadi, T. Carey, and J. Low. 2010. Procedures for the evaluation and analysis of sweetpotato trials. International Potato Center, Lima, Peru. Gr€uneberg, W.J., R.O.M. Mwanga, M. Andrade, and J. Espinoza. 2009. Selection methods. Part 5: Breeding clonally propagated crops. In: S. Ceccarelli, E.P. Guimarães, and E. Weltzien (eds.). Plant breeding and farmer participation. FAO, Rome, Italy. 1351 International Potato Center (CIP). 1999. CIP sweetpotato facts: Production, consumption, feed use. CIP, Lima, Peru. Jan. 2014. <http://www.cipotato. org/sweetpotato/facts/>. International Potato Center, Asian Vegetable Research and Development Center, and the International Board for Plant Genetic Resources. 1991. Descriptors for sweetpotato. In: Huaman, 1352 Z. (ed.). International Board for Plant Genetic Resources, Rome, Italy. MINAGRI. 2013. Final report. Republic of Rwanda, Ministry of Agriculture and Animal Resources (MINAGRI), National Dairy Strategy, Kigali, Rwanda. Ndirigwe, J. 2006. Adaptability and acceptability of orange and yellow-fleshed sweet potato genotypes in Rwanda. MSc thesis, Makerere University, Kampala, Uganda. RAB, Rwanda Agriculture Board. 2013. Submission of new sweetpotato varieties to the variety release committee. RAB, Kigali, Rwanda. RAB, Rwanda Agriculture Board. 2000. Rwanda agriculture board sweetpotato annual report. RAB, Huye, Rwanda. HORTSCIENCE VOL. 49(10) OCTOBER 2014