African Journal of Tropical Agriculture

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 7 (12), pp. 001-011, December, 2019. © International Scholars Journals

Full Length Research Paper

A pilot survey on retail fish marketing in Juba, South Sudan: Perceptions on motivation and challenges

John K.B Alosias

Department of Fisheries, School of Natural Resources & Environmental Studies, University of Juba, P. O. Box 82, Juba, South Sudan. E-mail: [email protected]. Tel: +211925377037.

Accepted 05 November, 2019

Abstract

Globally, fish marketing is an important income generating activity and a source of livelihood in many communities. In South Sudan, a newborn nation which attained its independence in 2011, no studies have been conducted in this area. This pilot study assessed retailers’ motivation towards fish marketing and the impact of some common major challenges affecting their growth. Using non-probability sampling method, 40 fish retailers in Konyokonyo and Custom markets in Juba were interviewed. Responses collected were analyzed using descriptive statistics and theoretical thematic analysis. Almost all retail fish sellers rely on fish marketing as their only source of income and livelihood. In spite of this dependency, the impacts of some major challenges were noted. Chief among them were fish spoilage due to improper handling and high cost of transportation. Alternative solutions and the need for a more thorough investigation have been suggested.

Keywords: Fish marketing, retailers, motivation, challenges, Konyokonyo market, Custom market, Juba, South Sudan.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 7 (12), pp. 001-006, December, 2019. © International Scholars Journals

Full Length Research Paper

Assessment of the genetic diversity in five generations of a commercial broodstock line of Litopenaeus vannamei shrimp

Patrícia Domingues de Freitas and Pedro Manoel Galetti Jnr.

Departamento de Genética e Evolução, Universidade Federal de São Carlos, Caixa Postal 676, 13565-905 - São Carlos, SP, Brazil (correspondence to P.D.F.)

Accepted 12 August, 2019

Abstract

Genetic variation among and within five generations of an inbred commercial captive line of Litopenaeus vannamei and genetic distance among them were evaluated by random amplified polymorphic DNA (RAPD), using descriptive and genetic similarity analyses for dominant markers at single- and multi-populational level. One hundred individuals were analyzed and 56 polymorphic loci were identified with a set of six primers screened in a painel of 38 decamer primers tested. The values obtained for F₅, F₆, F ₇, F ₈ and F₉ generations revealed a progressive increasing of genetic similarity throughout the five stocks, confirmed by Nei genetic diversity analysis, which values decreased from 0.27 to 0.22 at F₅ and F₉, respectively. Significant allele frequency differences were observed at most analyzed loci. Strong correlation (R² = 0.9845) was observed between genetic similarity and generation time, and genetic similarity could reach closer to 100% at 18-19 generation of this line.

Key words: Litopenaeus vannamei, genetic diversity, genetic drift, inbreeding, RAPD.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 7 (12), pp. 001-007, December, 2019. © International Scholars Journals

Full Length Research Paper

Genetic studies and a search for molecular markers that are linked to Striga asiatica resistance in sorghum

Mutengwa, C. S.¹*, Tongoona, P. B.² and Sithole-Niang, I.³

¹African Centre for Fertilizer Development, Hatcliff Estate, P.O. Box A469, Avondale, Harare, Zimbabwe.

²University of Natal, Pietermaritzburg Campus, African Centre For Crop Improvement, P. Bag X01, Scottsville, Pietermaritzburg 3209, South Africa.

³University of Zimbabwe, Department of Biochemistry, Faculty of Science. P.O. Box MP167 Mount Pleasant, Harare, Zimbabwe.

Accepted 14 October, 2019

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is important both as a food and feed crop in Zimbabwe. Its yield losses can be up to 100% when the crop is heavily infested by witchweeds [Striga asiatica (L.) Kuntze]. Witchweed resistant cultivars offer the most practical control option under smallholder (SH) farmer conditions and could become part of a sustainable integrated control strategy. Development of S. asiatica resistant cultivars by conventional breeding is slow and has been hampered by the lack of efficient and reliable screening techniques in breeding programs. Molecular markers that are linked to witchweed resistance can expedite the development of resistant cultivars through adoption of appropriate marker-assisted selection (MAS) strategies. The objectives of this investigation were to study the inheritance or low germination stimulant (lgs) production in cultivar SAR 29 and to identify molecular markers that are linked to this trait. Low germination stimulant production is one of the recognised mechanisms of witchweed resistance. A segregating F2 population derived from crosses between cultivars SV-1 (high germination stimulant producer, Striga-susceptible) and SAR 29 (low germination stimulant producer, Striga-resistant) was used for this purpose. Parental and F2 genotypes were screened for lgs production using the agar gel technique (AGT). Maximum germination distance (MGD) was used as the index of resistance. Deoxyribonucleic acid was extracted from agar gel-screened F2s, and DNA bulks were created from 16 resistant (MGD<10 mm) and 25 extremely susceptible (MGD>25 mm) progeny. Bulked segregant analysis (BSA) was done using random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers. Ninety-nine of the primers that were polymorphic between parent genotypes (10 SSR and 89 RAPD) were then used to screen a total of 77 segregating F2 progeny. Linkage analysis was performed using the computer software MAPMAKER 3.0b. Segregation ratios of high to low F2 stimulant producers did not differ significantly (P³0.05) from the expected ratio of 3:1. It was therefore deduced that a single recessive gene controlled lgs production in cultivar SAR 29. No molecular marker was found to be linked to the lgs locus. Instead, linkage analysis resulted in the construction of a molecular marker linkage map consisting of 45 markers that were distributed over 13 linkage groups (LGs). The other fifty-four loci, including the locus for lgs production, were completely unlinked and could not be assigned to any linkage group. The LGs consisted of 2-8 markers, identified at a LOD grouping threshold of 4.0. The map spanned a total distance of 494.5 cM, Haldane.

Key Words: Witchweed, Striga asiatica, bulked segregant analysis (BSA), Linkage map, marker assisted selection (MAS).

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 7 (12), pp. 001-005, December, 2019. © International Scholars Journals

Full Length Research Paper

Variation in diosgenin level in seed kernels among different provenances of Balanites aegyptiaca Del (Zygophyllaceae) and its correlation with oil content

Bishnu Chapagain and Zeev Wiesman*

Phyto-Lipid Biotechnology Laboratory, Department of Biotechnology Engineering, The Institutes for Applied Research, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105, ISRAEL

Accepted 15 September, 2019

Abstract

Balanites aegyptiaca (Zygopyllaceae) is a widely grown desert plant with multi-use potential. It is found in most of the African continent, the Middle East, and South Asia; however, this plant remains one of the most neglected plant species. Its seed kernel is used for oil extraction and the oil is used for human consumption and cosmetics. However, the oil cake is regarded as unsuitable for feeding because of the presence of many toxic substances. In this study, a spectrophotometric determination of diosgenin level and subsequent oil percentage analyses were carried out using the seed kernels of B. aegyptiaca collected from five Israeli provenances (Bet -Shean, Ein -gedi, Sapir, Samar, and Eilat) and five international locations (Burkina Faso, Senegal, Mali, Niger, and India). The results suggested that the sample from the Bet Shean Valley, which is considered the northern- most latitude where B. aegyptiaca naturally grows, contained the highest level of diosgenin as well as oil percentage; the Indian sample contained the lowest levels of both diosgenin and oil. The result also showed that there is a strong positive correlation (R² = 0.849) between diosgenin level and oil percentage in the B. aegyptiaca seed kernel.

Key words: Balanites aegyptiaca, provenances, kernel cake, diosgenin, oil content.