Characterisation of Taro (Colocasia Esculenta (L) Scott) germplasm collections in South Africa : towards breeding an orphan crop.

Doctor of Philosophy in Plant Breeding. University of KwaZulu-Natal, Pietermaritzburg, 2017.Amadumbe (Colocasia esculenta), better known as taro, is a traditional root crop widely cultivated in the coastal areas of South Africa. Taro is showing potential for commercialisation. However, very little is known about the genetic diversity, potential and its introduction and movement in South Africa. This study was undertaken to (1) determine the genetic diversity in the ARC taro germplasm collection using agromorphological characteristics and microsatellite markers, (2) to determine if it is possible to breed with local taro germplasm and (3) to determine the effect of four different environments (Roodeplaat, Umbumbulu, Owen Sithole College of Agriculture and Nelspruit) on ten agro-morphological characteristics of 29 taro landraces Taro germplasm was collected in South Africa in order to build up a representative collection. Germplasm was also imported from Nigeria and Vanuatu. The South African taro germplasm, and selected introduced germplasm, were characterised using agromorphological descriptors and simple sequence repeat (SSR) markers. Limited variation was observed between the South African accessions when agro-morphological descriptors were used. Non-significant variations were observed for eight of the 30 agromorphological characteristics. The 86 accessions were grouped into three clusters each containing 39, 20 and 27 accessions, respectively. The tested SSR primers revealed polymorphisms for the South African germplasm collections. Primer Uq 84 was highly polymorphic. The SSR markers grouped the accessions into five clusters with 33, 6, 5, 41 and 7 accessions in each of the clusters. All the dasheen type taro accessions were clustered together. When grown under uniform conditions, a higher level of genetic diversity in the South African germplasm was observed when molecular (SSR) analysis was performed than with morphological characterisation. No correlation was detected between the different clusters and geographic distribution, since accessions from the same locality did not always cluster together. Conversely, accessions collected at different sites were grouped together. There was also no clear correlation between the clustering pattern based on agro-morphology and SSRs. Thus, in order to obtain a more complete characterisation, both molecular and morphological data should be used. Although the results indicated that there is more diversity present in the local germplasm than expected, the genetic base is still rather narrow, as reported in other African countries. Fourteen distinct taro genotypes were planted as breeding parents and grown in a glasshouse. Flowering were induced with gibberellic acid (GA3). Crosses were performed in various combinations; however, no offspring were obtained. This might be due to the triploid nature of the South African germplasm. It might be useful to pollinate diploid female parents with triploid male parents or use advanced breeding techniques, like embryo rescue or polyploidization, to obtain offspring with the South African triploid germplasm as one parent. The triploid male parents might produce balanced gametes at low percentages, which can fertilize the diploid female parents. Twenty-nine taro accessions were planted at three localities, representing different agroecological zones. These localities were Umbumbulu (South of Durban - KZN), Owen Sithole College of Agricultural (OSCA, Empangeni, KZN) and ARC - Vegetable and Ornamental Plants (Roodeplaat, Pretoria). Different growth and yield related parameters were measured. The data were subjected to analysis of variance (ANOVA) and additive main effects and multiplicative interaction (AMMI) analyses. Significant GxE was observed between locality and specific lines for mean leaf length, leaf width, leaf number, plant height, number of suckers per plant, number of cormels harvested per plant, total weight of the cormels harvested per plant and corm length. No significant interaction between the genotype and the environment was observed for the canopy diameter and corm breadth. From the AMMI model, it is clear that all the interactions are significant for leaf length, leaf width, number of leaves on a single plant, plant height, number of suckers, number of cormels harvested from a single plant and weight of cormels harvested from a single plant. The AMMI model indicated that the main effects were significant but not the interactions for canopy diameter. The AMMI model for the length and width of the corms showed that the effect of environment was highly significant. There is a strong positive correlation between the number of suckers and the number of leaves (0.908), number of cormels (0.809) and canopy diameter (0.863) as well as between the number of leaves and the canopy diameter (0.939) and between leaf width and plant height (0.816). There is not a single genotype that can be identified as “the best” genotype. This is due to the interaction between the environments and the genotypes. Amzam174 and Thandizwe43 seem to be genotypes that are often regarded as being in the top four. For the farmer, the total weight of the cormels harvested from a plant will be the most important. Thandizwe43, Mabhida and Amzam174 seem to be some of the better genotypes for the total weight and number of cormels harvested from a single plant and can be promoted under South African taro producers. The local accessions also perform better than introduced accessions. It is clear that some of the introduced accessions do have the potential to be commercialised in South Africa. The study indicate that there are genetic diversity that can be tapped into for breeding of taro in South Africa. However, hand pollination techniques should be optimized. Superior genotypes within each cluster in the dendrograms as well as Thandizwe43, Mabhida and Amzam174 (identified by the AMMI analysis as high yielding) can be identified and used as parents in a clonal selection and breeding programme. Additionally, more diploid germplasm can be imported to widen the genetic base. The choice of germplasm must be done with caution to obtain germplasm adapted to South African climate and for acceptable for the South African consumers

Conservation of African Leafy Vegetables in South Africa

The nutritional and cultural importance of African Leafy Vegetables has become very important in South Africa in the past few years. Recent research has also confirmed these issues, leading to the incorporation of African Vegetables into the core business of the ARC. ARC-Roodeplaat wants to improve the distribution and conservation status of African Leafy Vegetables. Geographical collection data on Amarant, Cleome gynandra, Corchorus olitorius and Vigna inguiculata was obtained from the National Botanical Institute and the data was analyzed with DIVA and Flora map. Ecogeographical distribution maps were drawn to predict the possible distribution of the species. Germplasm of African Leafy Vegetables was collected during routine visits and the conservation status was discussed with participants in the study areas of Arthurstone in Bushbuckridge, Watershed near Ladysmith and Mars/Glenroy near Polokwane. Germplasm of various species were also collected in collaboration with the Plant Genetic Resource Centre (NPGRC) of the Department of Agriculture in Arthurstone and Watershed.The NPGRC included leafy vegetables in their mandate since this trip. Seed flow diagrams were used to discuss the Watershed community’s seed exchange systems. It was clear when discussing African leafy vegetables in communities that their conservation and utilization are declining. Also looking at the trendlines of African Vegetables availability and utilization it is clear that the use and availability of African Leafy vegetables are declining due to various reasons. Two major reasons are the negative image of the African Leafy Vegetables and the increased use of “exotic” vegetables like spinach and carrots. The active promotion, use and conservation of African Leafy Vegetables are important if we want to increase the production potential and potential contribution towards food security in South Africa. This will ensure that the status of these crops is enhanced, specifically their contributing towards sustainable nutrition as well as sustainable production. Results from promotion activities in the project (reported in another paper) indicated that the negative image of African Leafy Vegetables could be reversed and also had an affect on the roll-out of the project to other areas of research such as plant protection, nutritional analysis and food safety, crop science and indigenous knowledge systems.Key Words: Ecogeographical, Conservation, Leafy vegetable  

Effects of different penning conditions, feeding regimens and season on growth and carcass attributes of boars of a selected genetic line

The study tested the performance of intact male pigs from a selected genetic line subjected to differing feeding regimens and penning conditions. The trial was a 2 x 3 x 2 x 3 factorial design, consisting of winter and summer periods, three sire lines, two diets and three feeding regimens. The pigs were intact males grown over three phases, starter (25 to 50 kg); grower (51 to 80 kg) and finisher (81 to 105 kg).The pigs were randomly allocated to three feeding regimens, a controlled single feeding, ad libitum single feeding and ad libitum group feeding, with six animals per ad libitum group. This resulted in 96 pigs in six treatments with six replicates. The diets were high (HF) and low (LF) nutrient dense feeds, where the LF was 95% of the HF. Season affected growth; the winter animals had a significantly greater growth response, end-mass and average daily gain (ADG). The HF diet resulted in significant improved ADG, feed conversion ratio and protein deposition rate, especially during summer. However, end-mass, ADG and average protein deposition rates of controlled-fed pigs were significantly lower compared to the ad libitum group and single-fed animals. The hypothesis was affirmed that high-performing intact male pigs are sensitive to and affected by feeding regimens and penning conditions that will affect their production.http://www.sasas.co.za/nf201

Re-Creating Awareness of Traditional Leafy Vegetables in Communities

ABSTRACT Research and extension in South Africa has been labelling traditional leafy vegetables as weeds since the 1960s when they started encouraging households to produce food seen in the shops. This negative perception has led to an unwillingness to use and conserve these 'poverty foods', as many community members have labelled them. The status of these crops needed to be improved to help people realise the importance of these crops in their daily diet. Awareness activities in six communities made use of production training sessions in seven schools and eight community gardens, discussion groups, garden competitions, cooking competitions, recipe collection, awareness days, local resource collection activities, participatory selection and a radio talk. Discussions about use and conservation status of these crops during the data collection phase stimulated discussions on various aspects of these crops and caused an increased awareness about the poor conservation status within the communities, leading to the appointment of keepers of specific seed. The local resource collection efforts and gene bank actions caused community members to appreciate their natural resources more and emphasised the vulnerability of the crops, and their important role in keeping the biodiversity available for them and for future generations. In an effort to create awareness of the traditional plants at all levels within the community, schools (where possible) and community gardens were targeted during the training and awareness campaigns. The awareness campaigns culminated in a school garden and community garden competition, as well as a cooking competition. Participatory selection was used to expose the community members to new crops and to variations in the crops that they know. Community evaluation of these crops created a better understanding for researchers and community members, leading to improved cooperation. A noticeable increase in demand for seed and training on production methods was the result of the awareness activities within the communities

Nutrient content of eight African leafy vegetables and their potential contribution to dietary reference intakes

Nutrient content and potential contribution of one average portion towards nutritional requirements (recommended dietary allowance; RDA) of eight African leafy vegetables (ALVs) was determined. Compared to dark-green leafy vegetables (DGLVs) as sub-group, calcium and magnesium content were similar or considerably higher, vitamin C content was considerably lower, while pigweed had higher potassium content and spider flower similar folate content. All ALVs, except Chinese cabbage, had higher iron content. Black nightshade, pigweed, cowpea and spider flower leaves had higher b-carotene content than DGLVs. For children, pigweed and cowpea leaves emerged as good sources of vitamin A (>75% RDA), followed by spider flower, black nightshade, tsamma melon, Jew’s mallow and pumpkin leaves (50–75% RDA). For iron, pumpkin leaves provided 50–75% RDA. Black nightshade, tsamma melon, pigweed and cowpea leaves contributed 25–50% RDA, with Jew’s mallow, spider flower and Chinese cabbage providing <25% RDA. The ALVs were not a good source of zinc. Most ALVs were nutritionally similar to DGLVs. For most nutrients Chinese cabbage had considerably lower values than the other ALVs. Most of the ALVs can considerably contribute to requirements of vitamin A and, to a lesser extent, iron, both critical nutrients for developing countries.http://www.elsevier.com/locate/jfcahb201

The development of a SCAR marker for the identification of the potato cultivars Astrid and Mnandi

M.Sc.Mnandi and Astrid are two commercially important potato cultivars in South Africa. These two cultivars are closely related and are morphological virtually identical. It is, however, necessary to be able to distinguish between these two cultivars, because each of these cultivars has certain desirable characteristics. It was decided to use DNA markers, since DNA markers are not influenced by the environment and the polymerase chain reaction (PCR) based DNA markers are relatively easy, cheap and fast. It was decided to develop a sequenced characterized amplified region (SCAR) due to the problems with the reproducibility of random amplified polymorphic DNA (RAPDs). SCARs are derived from RAPD fragments by using the sequence of a RAPD derived fragment to design a set of new longer primers (usually 20-24mer) which are less sensitive to PCR conditions. Ten commercial potato cultivars (Astrid, Mnandi. BP,, Buffelspoort, VanderPlank, Up-to-Date, Hoevelder, Hertha, Pimpernel and Agria) were used in this study. Commercially available RAPD primers (102) were evaluated to seek a polymorphism unique to either Mnandi or Astrid. Thirtyseven polymorphisms between Astrid and Mnandi were identified but only three were unique. The polymorphism obtained with OPH-15 was however, not reproducible. The polymorphisms obtained with UBC 509 and 582, corresponding to the presence in Mnandi of a 300 and 900 by fragment respectively, were reproducible. These two fragments, UBC 509 3" and UBC 582900, were cloned into the pMosBlue TA cloning vector and sequenced. The identity if the inserts in the recombinant plasmids were verified with PCR and Southern blotting. The sequences were used to develop two sets of SCAR primers, SCAR UBC 509 3" and SCAR UBC 582900 . The two SCAR primer pairs were then used in PCR reactions. The SCAR UBC 509 300 primer pair amplified a fragment of 230 by in both Astrid and Mnandi and a fragment of 260 by in Mnandi. The polymorphism is thus retained and SCAR UBC 509 3" can be used to distinguish between Astrid and Mnandi. The SCAR UBC 582' primer pair amplify a fragment of 500 by in both Astrid and Mnandi as well as some other longer fragments. It was not possible to regain a polymorphism by either elevating the annealing temperature or by digesting the amplification products with restriction enzymes. SCAR UBC 582' could thus not be used to distinguish between Astrid and Mnandi

Agronomic evaluation and identification of potential cowpea (Vigna unguiculata L. Walp) genotypes in South Africa

Cultivar development of cowpea with increased grain yield depends on evaluation and selection of genetically unique and complementary breeding lines. The objective of this study was to evaluate cowpea collections using agronomic traits to select promising parents to develop breeding population. Twenty-two cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. Analysis of variance revealed significant genotypic (G) and locations (L) differences for all agronomic traits evaluated. Significant differences were also observed for most of the traits due to G X L, G X Year (Y), L X Y and G X L X Y interactions effects. The genotypes tested at two locations showed considerable genetic variation for the following agronomic traits that varied for number of leaves (NL) (20.08–179.78), leaf length (LL) (12.36–67.72 cm), leaf width (LW) (4.78–22.02 cm), number of branches (NB) (6.81–13.85), number of pods per plant (NPPP) (14.33–54.04), number of seeds per pod (NSPP) (11.7286.28), pod diameter (PD) (5.75–22.73 mm), plant height (PH) (6.57–233.71 cm), pod length (PL) (3.94–100.92 mm), hundred seed weight (HSWt) (8.11–49.52 g) and grain yield (GY) (0.10-1.48 t ha−1). Grain yield was significant and positively correlated with all of the traits except leaf length. The principal component analysis (PCA) identified four principal components (PCs) contributing to 73.62% of the total explained variation amongst the tested genotypes. The selected cowpea genotypes for most of agronomic characteristics are useful and candidate genetic resources for the development of breeding population in cowpea breeding and enhanced production and productivity for food and nutrition in the country

Re-Creating Awareness Of Traditional Leafy Vegetables In Communities

Research and extension in South Africa has been labelling traditional leafy vegetables as weeds since the 1960s when they started encouraging households to produce food seen in the shops. This negative perception has led to an unwillingness to use and conserve these &apos;poverty foods&apos;, as many community members have labelled them. The status of these crops needed to be improved to help people realise the importance of these crops in their daily diet. Awareness activities in six communities made use of production training sessions in seven schools and eight community gardens, discussion groups, garden competitions, cooking competitions, recipe collection, awareness days, local resource collection activities, participatory selection and a radio talk. Discussions about use and conservation status of these crops during the data collection phase stimulated discussions on various aspects of these crops and caused an increased awareness about the poor conservation status within the communities, leading to the appointment of keepers of specific seed. The local resource collection efforts and gene bank actions caused community members to appreciate their natural resources more and emphasised the vulnerability of the crops, and their important role in keeping the biodiversity available for them and for future generations. In an effort to create awareness of the traditional plants at all levels within the community, schools (where possible) and community gardens were targeted during the training and awareness campaigns. The awareness campaigns culminated in a school garden and community garden competition, as well as a cooking competition. Participatory selection was used to expose the community members to new crops and to variations in the crops that they know. Community evaluation of these crops created a better understanding for researchers and community members, leading to improved cooperation. A noticeable increase in demand for seed and training on production methods was the result of the awareness activities within the communities

Conservation Of African Leafy Vegetables In South Africa

The nutritional and cultural importance of African Leafy Vegetables has become very important in South Africa in the past few years. Recent research has also confirmed these issues, leading to the incorporation of African Vegetables into the core business of the ARC. ARC-Roodeplaat wants to improve the distribution and conservation status of African Leafy Vegetables. Geographical collection data on Amarant, Cleome gynandra, Corchorus olitorius and Vigna inguiculata was obtained from the National Botanical Institute and the data was analyzed with DIVA and Flora map. Ecogeographical distribution maps were drawn to predict the possible distribution of the species. Germplasm of African Leafy Vegetables was collected during routine visits and the conservation status was discussed with participants in the study areas of Arthurstone in Bushbuckridge, Watershed near Ladysmith and Mars/Glenroy near Polokwane. Germplasm of various species were also collected in collaboration with the Plant Genetic Resource Centre (NPGRC) of the Department of Agriculture in Arthurstone and Watershed. The NPGRC included leafy vegetables in their mandate since this trip. Seed flow diagrams were used to discuss the Watershed community&apos;s seed exchange systems. It was clear when discussing African leafy vegetables in communities that their conservation and utilization are declining. Also looking at the trendlines of African Vegetables availability and utilization it is clear that the use and availability of African Leafy vegetables are declining due to various reasons. Two major reasons are the negative image of the African Leafy Vegetables and the increased use of &apos;exotic&apos; vegetables like spinach and carrots. The active promotion, use and conservation of African Leafy Vegetables are important if we want to increase the production potential and potential contribution towards food security in South Africa. This will ensure that the status of these crops is enhanced, specifically their contributing towards sustainable nutrition as well as sustainable production. Results from promotion activities in the project (reported in another paper) indicated that the negative image of African Leafy Vegetables could be reversed and also had an affect on the roll-out of the project to other areas of research such as plant protection, nutritional analysis and food safety, crop science and indigenous knowledge systems