Dry and starchy orange-fleshed sweetpotato farmer varieties: Implications for fighting vitamin A defiency in East and Central Africa.

Sweetpotato is a major staple and co-staple root crop for millions of the rural people in Africa. Recently, it has been demonstrated to be of human health importance by combating vitamin A deficiency. This paper is a summary review of recent findings on the orange-fleshed sweetpotato (OFSP) farmer varieties (FV) from East Africa (EA) and their potential contribution to combat vitamin A deficiency (VAD) in Africa. Between 2000 and 2006, scientists from East and Central Africa collected several OFSP varieties from farmers' fields together with the white- and creamfleshed sweetpotato (WFSP) farmer varieties. Subsequent characterization studies using selected EA and exotic germplasm revealed critical findings for the future use of OFSP FV in Africa. Overall, molecular characterization showed that EA germplasm is distinct from non-African germplasm. It also showed that OFSP FV and WFSP FV from EA are very closely related. The two findings address suspicions that OFSP FV are of exotic origin. The OFSP FV differed from exotic OFSP on root dry matter (DM), starch and sucrose properties. Whereas the exotic OFSP are characteristically 'sweet and moist' (DM ≈ 25.0%, starch ≈50.0% and sucrose ≈ 10.3%), OFSP FV had characteristically high DM (≈33.0%), high starch (≈ 65.0%) and similar to the WFSP FV. It is these qualities that make sweetpotato a staple crop in Africa. However, root â-carotene content (BC) of some OFSP FV ['Ejumula', 240pmm; 'Carrot C', 259 ppm; 'Mayai', 264 ppm; and 'Zambezi', 233 ppm] nearly equaled that of 'Resisto' (271ppm), one of the popular OFSP cultivars in USA. These were shown to meet ≥400% of recommended daily allowance (RDA) with 250 g serving to a 5-8 year old child Other light orange-fleshed FV like 'ARA244 Shinyanga', 'K-118', 'K-134', 'K-46', 'PAL161', 'Sowola6', 'SRT52', and 'Sudan' had lower root BC than 'Resisto' and were shown to meet between 50-90% RDA of the child. In conclusion, OFSP FV from EA might show similar adaptation to sub- Sahara African environments as their sister WFSP and have a big potential to alleviate VAD. Also, breeding for acceptable high DM and high starch OFSP varieties for African consumers seems possibl

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

Stability of sweet potato cultivars to Alternaria leaf and stem blight disease

Alternaria leaf petiole and stem blight is an economically important disease of sweet potato (Ipomoea batatus L.) in tropical and sub-tropical environments. Published research on cultivar resistance to the sweet potato disease is limited. To evaluate cultivar reaction and stability to the disease, multi-location and replicated experiments were established in 12 environments in Uganda. Disease severity (area under disease progress curves - AUDPC), and cultivar root yield were also assessed. Significant differences (P<0.001) in AUDPC were detected among cultivars. Mean AUDPC ranged from 46.3 (Araka Red) to 78.4 (New Kawogo) across locations and seasons and the genotypes Araka Red and Tanzania had the lowest disease values. The location and season effects accounted for 67.1% and 7.5% of the total variance of AUDPC recorded among cultivars. The ranking of cultivars based on predicted AUDPC from Additive Main Effect and Multiplicative Interactive model (AMMI) showed that the NASPOT 1, the susceptible check, and New Kawogo were most susceptible to the disease in 11 of the 12 environments. Low and stable disease was consistently recorded and predicted on NASPOT 3 and the landrace cultivars Tanzania, Dimbuca, and Araka Red across environments. These results suggest that landrace cultivars had relative stability to the disease and wide adaptation across environments. These results suggest that AMMI statistical model and other multivariate techniques can be utilized for prediction of Alternaria disease stability in these locations

Uneven ground? Intersectional gender inequalities in the commercialized cassava seed system in Tanzania

Open Access JournalCassava (Manihot esculenta Crantz) is an important crop in Africa, especially to women who rely on it as a household staple food and source of income. In Tanzania, a recent move toward commercializing the cassava seed system resulted in significantly fewer women than men farmers, known as Cassava Seed Entrepreneurs (CSEs), producing improved seed for sale to fellow farmers. To document the barriers and constraints that create gender inequalities in the seed system to better understand women’s low representation and experiences in commercialized cassava seed production, we carried out a mixed-methods study in the Southern, Eastern, and Lake Zones of Tanzania in 2021. The quantitative analysis found differences in key individual and household characteristics between CSEs and farmers who aspired to be but did not participate as CSEs (or A-CSEs) as well as between women CSEs and women A-CSEs. After running a logistic regression, results indicated that sex of the farmer (being male) was a statistically significant predictor of participating as a CSE (p < 0.05), along with having a secondary education (p < 0.05) and owning a bank account (p < 0.01). The qualitative analysis highlighted challenges women CSEs face. They spoke about having lower access to and control over prerequisite resources, which are shaped by other intersecting social identities such as marital status and age. Gender stereotypes about their capacities to manage their seed businesses can demotivate them from carrying out their work as well as experiences dealing with discriminatory gender norms that limit their travel to attend trainings outside their communities. Despite these barriers, some women CSEs expressed positive outcomes that have accrued from their participation in commercialized seed production, including enhanced social status and improved living standards. For the commercialized cassava seed system to be more socially inclusive and sustainable, we argue that there is need to adopt gender-aware approaches to address the underlying barriers and biases that exclude women and other social groups. Development efforts should consider combining social change innovations with seed system interventions to address the inequitable norms and power relations that create unique constraints for women to operate effectively as seed entrepreneurs

Soil N, P, and land use efficiency under cassava/sweet potato intercropping system in Tanzania

Cassava sweet potato intercropping experiments were carried out at Ukiriguru (semiarid zone), Tanzania during the period from 1989-91. Four cassava varieties used were, Msitu Zanzibar, Alpim valenca, Mzimbirala and Liongo control. The second experiment tested four cassava planting densities, 6666, 10000, 13333 and 20000 plants per hectare. In the two trials, cassava was planted with single or double rows of sweet potato on the same ridge. Basal dressing of inorganic fertilizers at the rate of 60 N, 30 P, and 30 K kg/ha was applied to one half while other half was left unfertilized. Results showed that cassava and sweet potato can be successfully and profitably intercropped since they have different growth durations that allowed for yield gains through better utilization of space and time. A sound fertilization practice in cassava/ sweet potato associations was deemed necessary to ensure soil fertility maintenance. Although nutrient use was a limiting factor for increased productivity, other potential agronomic practices such as the use of organic matter, crop residues, farmyard manure and integration of leguminous crops, to improve soil texture and nutrients may be additional attractive options for farmers. Some of the other aspects that need more research are, adjusting cutting length of cassava to avoid early shading of the intercrop, better rooting cultivar use, and type of seedbed used for sweet potato cuttings. Further studies are also warranted to know specific nutrient requirements in this intercrop and critical nutrient demand times of the individual crops in this association