Genotypey by environment interaction, genetic variability and path analysis for grain yield in elite soybean [Glycine max (L.) Merrill] lines.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.Soybean [Glycine max (L.) Merrill] is the world’s leading source of protein and vegetable oil. However, its productivity is still low in the region due to limited availability of stable and high yielding cultivars. Therefore, the objectives of this study were: (1) to determine the magnitude of genotype by environment interaction and stability of elite soybean lines for seed yield, (2) to establish trait profiles of 25 soybean genotypes and to study the associations among characters, their direct and indirect effects on grain yield and (3) to estimate genetic parameters of traits related to seed yield and to analyse genetic diversity among elite soybean lines. To achieve these objectives, 25 genotypes (20 elite soybean lines and five commercial checks) were evaluated in multi-location trials conducted in the 2017/18 rainy season using six sites in four countries viz. Zambia, Malawi, Zimbabwe and Mozambique. Both AMMI and GGE biplot analyses indicated Lusaka West as the highest yielding and most informative environment and could be useful for selecting specifically adapted genotypes. Rattray Arnold Research Station was the most ideal environment as it was both informative and highly representative. The soybean lines TGx2002-17DM, TGx2001-10DM, TGx2001-18DM, TGx2014-24FM, TGx2001-6FM and TGx2002-3DM exhibited specific adaptation. Both GGE and AMMI models showed that TGx2014-5GM was more stable than the checks and was second to the highest yielding check. The genotype by trait (GT) and correlation coefficient analyses revealed that pod number per plant and hundred seed weight were the most positively correlated traits with grain yield, while days to 50% flowering had a negative association with grain yield. Sequential path analysis, showed that the number of pods per plant and hundred seed weight had the highest positive and significant direct effects on seed yield, implying that these two traits could be used as selection criteria for seed yield in soybean. The soybean lines TGx2014-5GM and TGx2002-23DM had good combinations of high yields with large seed size and high pod number. The analysis of genetic variability showed small differences between PCV and GCV values for all the traits except for pod clearance. This implied that there were minimal effects of the environment and high contribution of the genes in the phenotypic expression of the traits, except for pod clearance, which was more affected by the environment. Moderate GCV values of 13.45% and 13.49%, high heritability values of 70% and 69% and GAM values of 23.24% and 23.04% were recorded for grain yield and number of pods per plant, respectively. Only two principal components, PC1 and PC2 accounted for the variation, with a cumulative contribution of 68.25%. All the seven traits were useful in discriminating the genotypes as they had high eigenvalues in either PC1 or PC2. The 25 soybean genotypes were grouped into two main clusters, which were further sub-divided into eight sub-clusters based on the seven morphological characters. The genotypes TGx2014-5GM, checks SC Safari and SC Squire in sub-cluster 6 had the highest means of the most desirable traits (large seed size, high pod number per plant and seed yield). The three genotypes could be used in hybridisation programmes for improvement of grain yield, seed size and number of pods of the genotypes. Overall, the study identified soybean lines that could potentially be released as cultivars in the four southern African countries or used as parents in future soybean improvement programmes. It also revealed traits that could be used for indirect selection of seed yield and high genetic diversity among the genotypes for possible exploitation in soybean breeding programmes to increase seed yield

The prevalence of intermittent water supply in Southern Africa

Thesis (MEng)--Stellenbosch University, 2019.ENGLISH ABSTRACT: The ability to supply potable water by water utilities in Southern Africa is being threatened by several factors including increased population and urbanisation, increased demand, water scarcity, inconsistent sources of energy and deteriorating infrastructure. In this regard, many water utilities in this region have resorted to intermittent water supply (IWS) as a management strategy, in an attempt to meet consumers’ basic needs as well as preserve the integrity of the already deteriorated infrastructure. This, over the years, has had a significant impact on the quality and quantity of water distributed. Although most water utilities report improved service delivery, only a statistical demonstration of trends over a period can demonstrate, as well as justify or dispute these performance reports. This research set out to determine three aspects relating to IWS in 11 countries across Southern Africa over a period of 10 years, between 2008 and 2017. The aspects included the variation in the hours of supply, the leading causes of IWS and the extent of IWS in a Southern African country using the case study of South Africa. Furthermore, the research was based on statistics and incorporated secondary water supply data for Angola, Botswana, Swaziland (Eswatini), Lesotho, Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia and Zimbabwe. An attempt was made to gather primary data from 252 water utilities across the 11 countries using an emailed questionnaire, but the response rate was only 0.8%. The secondary data used was gathered from annual reports and online databases, and was analysed using Microsoft Excel and mapped using ArcGIS software packages. The results demonstrate an increase in the population in Southern Africa with access to piped water connections, which was further highlighted by the reduction in the regional connection ratio, which reduced from 53.6 to 40.5 people per connection over the 10 years. The weighted average hours of supply for the region decreased from 21.5 to 18.4 per day between 2008 and 2017, while that for non-revenue water for the region increased from 36.5% to 41.7%. The results also revealed that there are three dominant causes of IWS among water utilities in Southern Africa, which includes maintenance/bursts/failed infrastructure, increased demand and urbanisation, as well as inadequate water resources. In the case study of South Africa, it was estimated that 39.3% of the South African population is affected by some form of intermittency, with 9.2 million of the affected people being from Gauteng and KwaZulu-Natal provinces. It was also found that of the 54 municipalities that practise IWS, 29 of them probably practise permanent IWS. The results further revealed that the leading causes of permanent IWS in South Africa are increased demand, inadequate pressure/high water loss and vandalism to infrastructure. The results of this research can be referred to by management teams, policy makers and funding institutions to assist in the allocation of resources. The results can also be used to compare country performances against others in the region.ENGLISH ABSTRACT: Die vermoë om drinkwater deur watervoorsieners in Suider-Afrika te voorsien, word bedreig deur verskeie faktore, waaronder toenemende bevolkingsgetalle en verstedeliking, 'n groter aanvraag, waterskaarste, onbetroubare energiebronne en verswakkende infrastruktuur. Baie watervoorsieners in die streek begin gebruik maak van onderbroke watervoorsiening (OWV) as 'n bestuurstrategie, in 'n poging om in die basiese behoeftes van die verbruiker te voorsien en om die integriteit van die reeds verswakte infrastruktuur te bewaar. Dit het deur die jare 'n beduidende invloed gehad op die kwaliteit van en hoeveelheid water wat versprei word. Alhoewel die meeste watervoorsieners verbeterde dienslewering rapporteer, kan slegs 'n statistiese demonstrasie van tendense oor 'n periode hierdie prestasieverslae regverdig of betwis. Hierdie navorsing het ten doel gehad om drie aspekte rakende OWV in 11 lande in Suidelike Afrika oor 'n periode van tien jaar, tussen 2008 en 2017, vas te stel. Die aspekte sluit in die wisseling in die ure van watervoorsiening, die grootste oorsake van OWV en die omvang van OWV in 'n land in Suider-Afrika, met behulp van die gevallestudie van Suid-Afrika. Die navorsing is verder gebaseer op statistiese en sekondêre watervoorsieningsdata vir Angola, Botswana, Swaziland (Eswatini), Lesotho, Malawi, Mosambiek, Namibië, Suid-Afrika, Tanzanië, Zambië en Zimbabwe. Daar is gepoog om primêre data van 252 watervoorsieners in die 11 lande in te samel, met behulp van 'n e-posvraelys, maar die respons was slegs 0,8%. Die sekondêre data wat gebruik is, is versamel uit jaarverslae en aanlyn-databasisse en is geanaliseer met behulp van Microsoft Excel en gekarteer met behulp van ArcGIS-sagtewarepakkette. Die resultate toon 'n toename in die bevolking in Suider-Afrika met toegang tot waterkonneksies, wat bewys word deur die streekswaterkonneksieverhouding, wat gedurende die tien jaar van 53.6 tot 40.5 mense per konneksie verminder het. Die geweegde gemiddelde ure van waterlewering vir die streek het tussen 2008 en 2017 van 21.5 tot 18.4 afgeneem, terwyl nie-inkomsgewende waterverbruik (onder andere as gevolg van lekkasies), van 36.5% tot 41.7% gestyg het. Die resultate het ook aan die lig gebring dat daar drie hoofoorsake van OWV in Suider-Afrika is, insluitend instandhouding/pypbreuke/faling van infrastruktuur, verhoogde aanvraag en verstedeliking, asook onvoldoende waterbronne. In die gevallestudie van Suid-Afrika word beraam dat 39.3% van die Suid-Afrikaanse bevolking geraak word deur een of ander vorm van onderbroke watervoorsiening, met 9.2 miljoen van die geïmpakteerde bevolking afkomstig uit Gauteng en KwaZulu-Natal provinsies. Daar is ook gevind dat van die 54 munisipaliteite wat OWV beoefen, 29 waarskynlik permanente OWV toepas as ‘n formele watervoorsieningstrategie. Die resultate het verder aan die lig gebring dat die mees algemene oorsake van permanente OWV in Suid-Afrika verhoogde aanvraag, onvoldoende druk gekoppel aan verhoogde waterverliese en vandalisme van infrastruktuur is. Die resultate van hierdie navorsing kan deur bestuurspanne, beleidmakers en finansieringsinstansies gebruik word vir die toewysing van waterhulpbronne en –infrastruktuur. Die resultate kan ook gebruik word om watervoorsieningstrategieë van lande in die streek met ander in die streek te vergelyk.Master

Intermittent water supply: a South African perspective

The prevalence of intermittent water supply in South Africa was investigated in this research study. Data on intermittent water supply in South Africa was collated by considering the following four sources: a targeted water services provider survey; published databases and related reports; open-access publications, such as online media articles; and field visits by the project team to selected areas. The data were spatially and temporally analysed to determine the prevalence of intermittent water supply. The population affected by intermittent water supply increased by ~26% between 2008 and 2017, which exceeds the population increase of ~12% over the same period. Moreover, 22 million people in South Africa were affected by intermittent water supply in 2017. Results from this study confirm an increased prevalence of intermittent water supply over time and show that 65 of the 231 municipalities in South Africa supplied water intermittently, 32 had continuous water supply and 134 had no data. Fundamentally, the outcomes highlight the widespread occurrence of intermittent water supply in South Africa, which is in line with the poor state of water services delivery in South Africa, as portrayed in the 2018 National Water and Sanitation Master Plan by the national Department of Water and Sanitation