Browsing by Author "Mabhaudhi, Tafadzwanashe."

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Application and evaluation of aquacrop, dssat and simple model in modelling yield water use of selected underutilised cereal crops.
(2021) Nzimande, Thembelihle Nkosingiphile Millicent.; Mabhaudhi, Tafadzwanashe.; Chimonyo, Vimbayi Grace Petrova.
The study compared yield, biomass, and water use (WU) for maize, sorghum, and millet simulated using three crop models of varying complexity: AquaCrop, DSSAT and the SIMPLE model. The hypothesis was that there is no significant difference between simple and complex models of estimating yield, biomass and WU. A standard set of crop parameters was used to develop crop files for all three models. Similar soil, climate and management descriptions attained from the Ukulinga Research Farm were used across the models. Six general circulation models (GCMs) were used as climate input data to model past, present, mid-, and late-century climate change impacts on cereal crops. The effect of irrigation (as a management practice) on yield and water use was assessed using the mid-century projections. The performance of the three models was observed to be statistically different. Based on the mean bias error, all models overestimated yield, but the lowest overestimation was with AquaCrop (0.22 t/ha) followed by DSSAT (0.24 t/ha) and the SIMPLE model (0.69 t/ha). Other statistical indicators, viz., RMSE and R2, illustrate that the simulation of yield and WP in AquaCrop was more satisfactory than DSSAT and the SIMPLE model. Across all the time scales, it was observed that AquaCrop simulated the highest yield and biomass, and the SIMPLE model simulated the lowest yield across the GCMs, which were inconsistent. Applying a higher amount of irrigation at more frequent intervals resulted in higher yield, biomass and WP. AquaCrop showed the highest simulated mean yield for maize (8.34 t/ha), millet (6.86 t/ha) and sorghum (5.28 t/ha). Highest WP was observed under AquaCrop for maize (21 kg/ha/mm) and millet (15.10 kg/ha/mm), the SIMPLE model for sorghum (13.37 kg/ha/mm). The study confirms that DSSAT requires relatively more input data but does not always perform more satisfactorily. The SIMPLE model requires fewer input requirements than AquaCrop and DSSAT; however, it is less sensitive to management changes. AquaCrop had relatively incomparable results to DSSAT and the SIMPLE model and was observed as the most suitable model for simulating yield, biomass, and WU of the selected cereal NUS under climate change and irrigation management scenarios. Before their application, it is essential to calibrate crop growth parameters for local conditions or use parameters from local field studies when applying complex crop models such as DSSAT specifically for marginal environments, such as South Africa. On the other hand, AquaCrop performed reasonably well with minimal input requirements, confirming its application in datalimited and marginal environments. However, it is recommended that there must be calibration for all the models using inputs specific to locations.
Assessing climate change impacts on productivity of sugarbeet and sugarcane using aquacrop.
(2018) Mokonoto, Ofentse.; Kunz, Richard Peter.; Mabhaudhi, Tafadzwanashe.
Globally, the use of biofuels has grown over the years and their importance in helping to reduce a) dependency on fossil-based fuels and b) greenhouse emissions has been widely recognised. Various feedstocks are used for biofuels, viz. sugar-based crops for bioethanol production and oil from vegetable crops for biodiesel production. The research presented in this study focused on sugar crops such as sugarcane and sugarbeet. The sugarcane industry is widely established in South Africa, whereas sugarbeet is still a new crop and hence, there is little information on its water use efficiency (WUE) and potential yields under South African growing conditions. Overall, there is a need to better understand the agricultural potential and water use requirements of these feedstocks, in order to grow the biofuels industry in South Africa in a sustainable manner. Furthermore, climate change poses a threat to global food security as well as to biofuel feedstock production. There are uncertainties regarding the potential impacts of climate change on the yield and WUE of agricultural crops. One of the main objectives of this study was to calibrate the AquaCrop crop model for sugarcane and sugarbeet using experimental datasets. This study then followed a modelling approach to estimate dry yields and WUEs of these two sugar feedstocks to add to the existing knowledge base for potential biofuel production in South Africa. Sugarbeet was planted at the Ukulinga research farm and field equipment was used to collect data for the calibration of the crop model to better estimate attainable yield and WUE. Growth and yield datasets were provided by the South African Sugarcane Research Institute to calibrate the model for sugarcane, as well as validate AquaCrop for both feedstocks. The performance of the crop model was tested using various statistical methods. The model’s performance was satisfactory after calibrating it for sugarcane. However, the calibration process was compromised by the lack of sufficient leaf area index data. For sugarbeet, AquaCrop simulated the canopy cover, yield and WUE well, but tended to over-estimate observations. For the validation process, simulations closely matched the observed yields for both feedstocks. However, the model’s ability to simulate soil water content at Ukulinga was considered unsatisfactory. The calibrated AquaCrop model was used for long term assessments of yield and WUE. Baseline simulations were undertaken using 50 and 30 years of climate data and the results indicated that the 30 years of data could adequately estimate the long-term attainable productivity of sugarcane and sugarbeet. According to the literature, an ensemble approach to climate change modelling reduces uncertainty in long-term assessments. Hence, climate projections from several global climate models (GCMs), that were downscaled using dynamical and statistical approaches, were obtained and used to assess the potential impacts of climate change on yield and WUE of the selected feedstocks. An increase in yield and WUE of both feedstocks is projected in the distant future. The statistically downscaled GCMs projected higher increases compared to the dynamically downscaled GCMs. Increases in future WUE are much higher compared to yields projections. The so-called “CO2 fertilisation” effect largely benefits C3 crops (sugarbeet) with regards to yield improvements. However, the results also show that C4 crops (sugarcane) also benefit from improved WUE. Both sugarcane and sugarbeet will benefit from the anticipated climate change when planted in February and May, respectively. However, it is recommended that other planting dates should be studied for sugarcane.
Assessing the water productivity of sweet potato (Ipomoea batatas (L.) Lam.)
(2022) Mthembu, Thando Lwandile.; Kunz, Richard Peters.; Mabhaudhi, Tafadzwanashe.
In water-stressed countries like South Africa, the reliable quantification of actual crop evapotranspiration (ETA) and yield across a wide range of environments is important for improved agricultural water management. In addition, researchers are shifting their primary focus from well-studied major crops to neglected and underutilised crops. Orange-fleshed sweet potato (Ipomoea batatas (L). Lam.) remains an underutilised root and tuber crop (RTC) in South Africa, despite its potential as being nutrient-dense, high yielding and water use efficient, as reported in local literature. When compared to conventional crops, knowledge is limited on the water use and yield of RTCs under rainfed and precision agricultural production in South Africa. It is therefore important to further investigate whether the water use of orangefleshed sweet potato (OFSP) will hinder its production at the commercial scale. This study attempted to contribute towards the limited research on the crop water productivity (CWP) of OFSP. A rainfed field trial with optimum fertilisation was conducted at Fountainhill Estate (KwaZulu-Natal, South Africa) to estimate seasonal ETA, yield and CWP. The soil water balance method was used to determine ETA accumulated over the growing season from 14 December 2021 to 11 April 2022. Total ETA for OFSP was estimated at 468.13 mm, which was used to calculate fresh and dry CWP values of 7.45 and 2.59 kg m-3 , based on final fresh and dry tuber yields of 34.89 and 12.12 t ha-1 , respectively. Harvested tuber and above-ground biomass samples were sent to a laboratory to analyse nutrient content (NC). The nutritional water productivity (NWP) was determined as the product of CWP and NC, highlighting the potential of OFSP to alleviate malnutrition, especially if grown in rural communities. Field observations were used to partially calibrate the Soil Water Balance (SWB) and AquaCrop models. These models were used to simulate ETA, yield and biomass accumulation, from which CWP and NWP were calculated. Compared to observations, AquaCrop provided a better estimate of CWP (2.55 kg m-3 ) relative to the SWB model (1.16 kg m-3 ). However, AquaCrop simulated higher soil water content relative to measurements from volumetric soil water content sensors. This study showed that under suitable management practices, OFSP has the potential to be grown commercially, since the crop can produce high yields and nutrient contents under rainfed agricultural production. However, to improve production, future studies need to conduct research to improve tuber yield and biomass accumulation. Furthermore, the AquaCrop and SWB models should be calibrated and validated across different agroecological zones in South Africa.
Assessment of bambara groundnut (vigna subterranean L. verdc) recombinant inbred lines (rils) for agro-morphological traits, cooking quality properties and nutritional composition.
(2022) Ruzive, Amanda.; Mabhaudhi, Tafadzwanashe.; Shayanowako, Admire Isaac Tichafa.; Govender, Laurencia.
Assessment of maize crop health and water stress based on multispectral and thermal infrared unmanned aerial vehicle phenotyping in smallholder farms.
(2021) Brewer, Kiara Raynise.; Clulow, Alistair David.; Sibanda, Mbulisi.; Mabhaudhi, Tafadzwanashe.
Abstract available in PDF.
Community perceptions of an early warning system: a case study of Swayimane, UMshwathi Local Municipality’s lightning warning system.
(2021) Ndlela, Senelisiwe.; Mabhaudhi, Tafadzwanashe.; Naidu, Uma Maheshvari.
This study attempts to understand community perceptions of a lightning warning system in the community of KwaSwayimane. The study therefore takes a detailed look at the local community’s views on and insights into the warning system, and how these are shaped by the cultural practices and beliefs embedded in indigenous/local knowledge. The study was carried out at KwaSwayimane, and adopted a mixed methodology, making it both qualitative and quantitative. It involved 100 participants who engaged in questionnaires, focus group discussions and face-to-face interviews. Social constructionism and symbolic interactionism theories were used to analyze the insights gathered during data collection. Findings revealed that the community has recommendations on how to improve their experience of the lightning warning system installed in the area (especially in the context of the dissemination of the warning messages) and these recommendations involve integrating their local/indigenous understandings for protection against lightning strikes with the existing system.
Crop suitability mapping for underutilized crops in South Africa.
(2022) Mugiyo, Hillary.; Mabhaudhi, Tafadzwanashe.; Chimonyo, Vimbayi Grace Petrova.; Kunz, Richard Peter.
Several neglected and underutilised species (NUS) provide solutions to climate change and create a Zero Hunger world, the Sustainable Development Goal 2. However, limited information describing their agronomy, water use, and evaluation of potential growing zones to improve sustainable production has previously been cited as the bottlenecks to their promotion in South Africa's (SA) marginal areas. Therefore, the thesis outlines a series of assessments aimed at fitting NUS in the dryland farming systems of SA. The study successfully mapped current and possible future suitable zones for NUS in South Africa. Initially, the study conducted a scoping review of land suitability methods. After that, South African bioclimatic zones with high rainfall variability and water scarcity were mapped. Using the analytic hierarchy process (AHP), the suitability for selected NUS sorghum (Sorghum bicolor), cowpea (Vigna unguiculata), amaranth and taro (Colocasia esculenta) was mapped. The future growing zones were used using the MaxEnt model. This was only done for KwaZulu Natal. Lastly, the study assessed management strategies such as optimum planting date, plant density, row spacing, and fertiliser inputs for sorghum. The review classified LSA methods reported in articles as traditional (26.6%) and modern (63.4%). Modern approaches, including multicriteria decision-making (MCDM) methods such as AHP (14.9%) and fuzzy methods (12.9%), crop simulation models (9.9%) and machine-learning-related methods (25.7%), are gaining popularity over traditional methods. The review provided the basis and justification for land suitability analysis (LSA) methods to map potential growing zones of NUS. The review concluded that there is no consensus on the most robust method for assessing NUS's current and future suitability. South Africa is a water-scarce country, and rainfall is undoubtedly the dominating factor determining crop production, especially in marginal areas where irrigation facilities are limited for smallholder farmers. Based on these challenges, there is a need to characterise bioclimatic zones in SA that can be qualified under water stress and with high rainfall variation. Mapping high-risk agricultural drought areas were achieved by using the Vegetation Drought Response Index (VegDRI), a hybrid drought index that integrates the Standardized Precipitation Index (SPI), Temperature Condition Index (TCI), and the Vegetation Condition Index (VCI). In NUS production, land use and land classification address questions such as “where”, “why”, and “when” a particular crop is grown within particular agroecology. The study mapped the current and future suitable zones for NUS. The current land suitability assessment was done using Analytic Hierarchy Process (AHP) using multidisciplinary factors, and the future was done through a machine learning model Maxent. The maps developed can contribute to evidence-based and site-specific recommendations for NUS and their mainstreaming. Several NUS are hypothesised to be suitable in dry regions, but the future suitability remains unknown. The future distribution of NUS was modelled based on three representative concentration pathways (RCPs 2.6, 4.5 and 8.5) for the years between 2030 and 2070 using the maximum entropy (MaxEnt) model. The analysis showed a 4.2-25% increase under S1-S3 for sorghum, cowpea, and amaranth growing areas from 2030 to 2070. Across all RCPs, taro is predicted to decrease by 0.3-18 % under S3 from 2050 to 2070 for all three RCPs. Finally, the crop model was used to integrate genotype, environment and management to develop one of the NUS-sorghum production guidelines in KwaZulu-Natal, South Africa. Best sorghum management practices were identified using the Sensitivity Analysis and generalised likelihood uncertainty estimation (GLUE) tools in DSSAT. The best sorghum management is identified by an optimisation procedure that selects the optimum sowing time and planting density-targeting 51,100, 68,200, 102,500, 205,000 and 300 000 plants ha-1 and fertiliser application rate (75 and 100 kg ha-1) with maximum long-term mean yield. The NUS are suitable for drought-prone areas, making them ideal for marginalised farming systems to enhance food and nutrition security.
Detection and early warning of lightning and extreme storm events in KwaZulu-Natal, South Africa.
(2020) Mahomed, Maqsooda.; Clulow, Alistair David.; Mabhaudhi, Tafadzwanashe.; Savage, Michael John.; Chetty, Kershani Tinisha.; Strydom, Sheldon.
Abstract available in pdf.
Developing integrated climate change adaptation strategies using the water-energy-food nexus approach: a case study of the Buffalo River catchment, South Africa.
(2023) Dlamini, Nosipho.; Senzanje, Aidan.; Mabhaudhi, Tafadzwanashe.
South Africa’s climate has high spatial and temporal variability. Literature on historical rainfall patterns shows substantial declines in rainfall across the country, except in south-western South Africa, which displays increasing trends. Under the Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios, statistically downscaled rainfall projections show different patterns across South Africa throughout the 21st century. Literature indicates that this uncertainty will majorly impact South Africa’s surface water availability as its main input variable is rainfall; hence, all possible outcomes need to be planned for. Planning should include the energy and food production sectors as they primarily depend on the water sector. The Buffalo River catchment, situated in the northern parts of KwaZulu-Natal, South Africa, is a high rainfall receiving area, with a mean annual precipitation of 802 mm. Despite its abundant rainfall, the catchment has had its fair share of droughts, significantly impacting livelihoods and socio-economic activities. Recent reports indicate that the Buffalo River catchment’s surface water storage facilities are insufficient to meet the population’s demands by 2050. A detailed water resources assessment is required to confirm and quantify the possible alterations that climate change could cause to the catchment’s hydrology before any actions can be taken, especially regarding increasing the water storage capacity of the catchment. As such, this study aims to investigate and assess the impacts of climate change on the Buffalo River catchment’s surface water availability and reliability of water resources in meeting projected water demands, with a specific focus on agricultural and energy generation water demands. Furthermore, the study aims to develop integrated water resources adaptation strategies to increase water, energy and food security within the catchment. Due to its transdisciplinary nature, the Water-Energy-Food (WEF) nexus methodology was used as an analytical tool to carry out the research’s objectives. The study was based on the null hypotheses of climate change not varying surface water availability and reliability, and that the optimized CC water management strategies will not yield any improvements in merging potential gaps between water supply and demands. Study findings indicate that the Buffalo River catchment is anticipated to receive increases in precipitation magnitude and fluctuations throughout the 21st century. However, the increases in surface water availability that result from the anticipated rainfall increases are insufficient and unreliable to meet the rise in demands for water within the catchment, more so the irrigation demands. Through investigating the catchment’s already-existing proposed climate change policy interventions for water resources management, the study found that they were centred around boosting domestic water provisions whilst only meeting <3% of projected demands by the energy and agricultural sector. As such, by optimizing these policy plans using the WEF nexus’ Climate, Land-Use and Water Strategies (CLEWS) framework’s analytical tools, integrated climate change adaptation strategies were formulated, which were modelled to significantly improve the water storage capacity of the catchment, as well as water allocations and distribution among water users. The study concluded that the Buffalo River catchment’s surface water availability is expected to increase under climate change, however, current water storage capacity is not reliable to meet water demands throughout the 21st century. Lastly, the study also concluded that the catchment does possess immense potential for improved surface water availability to merge the gap between its water supplies and demands. Thus, the null hypotheses stipulated in this research are rejected. For discussions, policymaking and general research related to these improvements in water resources management in the Buffalo River catchment, the climate change adaptation strategies established in this research are recommended. Also, based on model evaluation statistics, the WEF nexus was successful in examining the interrelations among WEF resources, and is recommended for future studies to examine long-term integrated demand-supply strategies for WEF sectors.
Development of an air quality early warning system for the eThekwini and Msunduzi municipalities.
(2023) Sithole, Siphesihle Fortunate.; Mabhaudhi, Tafadzwanashe.; Botai, Joel.
The aim of this study was to assess the source and concentration of criteria air pollutants, as conditioned by the weather and climate conditions, in the eThekwini and Msunduzi Local Municipalities, in the KwaZulu-Natal Province. The outcomes of this assessment will contribute towards the establishment of an appropriate early warning system for the two municipalities, in order to reduce the risk of exposure to air pollution and to avoid the associated health risks. For this purpose, the study adopted various methods and tools to determine the status of air pollution within the municipalities, in terms of the exceedance of particles with an aerodynamic of less, or equal to, 2.5 micrometres (PM2.5) and less than 10 micrometres (PM10) of sulphur dioxide (SO2), ozone (O3) and nitrogen dioxide (NO2). The National Ambient Air Quality Standards (NAAQS) and World Health Organisation (WHO) guidelines were used as a threshold for determining these exceedances. In addition, GIS software was used to determine the spatial distribution of the air pollutants, while the IBM SPSS Statistics Version 27 was used to determine the Pearson correlation between the meteorological parameters and the air pollutant concentration levels within the municipalities. The Openair package in R-Studio was used to determine the wind direction and wind speed within the areas, while the US EPA method was adopted to determine the Air Quality Index (AQI). The results of the exceedance study indicated that most of the air pollutants that were emitted exceeded those of the WHO and NAAQS thresholds, especially PM2.5 and PM10, mostly during the winter period, when temperature inversion is at its strongest. A positive relationship was determined between the air pollutants and meteorological conditions. It is worth noting that the meteorological conditions were not the only factors influencing the concentration levels, but the emissions from industries and vehicles, the burning of fossil fuels for domestic purposes and landfill sites were also observed to be contributing factors to the air pollutant concentration within the municipalities. The results of the proposed AQI showed that most of the people living in eThekwini, especially those living south of Durban, were exposed during winter season to high concentrations of PM10, PM2.5 and SO2, while those of the proposed AQI in the Msunduzi Municipality were, in most cases, observed to be moderate throughout the seasons. In two cases, the Pietermaritzburg CBD and at the Pietermaritzburg Airport, the AQI was recorded as hazardous during spring and summer, respectively. According to the proposed AQI, the most dominant air pollutants are NO2 and SO2. The findings of the study suggest that people living in eThekwini and Msunduzi communities may breathe air harmful to their health and well-being, especially those living near industries and national highways. The overall findings of the study showed that the constitutional right of those living within these municipalities, “to live in an environment that is not iv harmful to their health and wellbeing”, is being violated, since they are being exposed to high air pollutant concentrations.
Drought tolerance and water-use of selected South African landraces of Taro (Colocasia esculenta L. schott) and Bambara groundnut (Vigna subterranea L. Verdc)
(2012) Mabhaudhi, Tafadzwanashe.; Modi, Albert Thembinkosi.
Issues surrounding water scarcity will become topical in future as global fresh water resources become more limited thus threaten crop production. Predicted climate change and increasing population growth will place more pressure on agriculture to produce more food using less water. As such, efforts have now shifted to identifying previously neglected underutilised species (NUS) as possible crops that could be used to bridge the food gap in future. Taro (Colocasia esculenta L. Schott) and bambara groundnut (Vigna subterranea L. Verdc) currently occupy low levels of utilisation in South Africa. Both crops are cultivated using landraces with no improved varieties available. Information describing their agronomy and water–use is limited and remains a bottleneck to their promotion. The aim of this study was to determine the drought tolerance and water–use of selected landraces of taro and bambara groundnut from KwaZulu-Natal, South Africa. In order to meet the specific objectives for taro and bambara groundnut management, an approach involving conventional and modelling techniques was used. Three taro landraces [Dumbe Lomfula (DL), KwaNgwanase (KW) and Umbumbulu (UM)] were collected from the North Coast and midlands of KwaZulu-Natal, South Africa, in 2010. The UM landrace was classified as Eddoe type taro (C. esculenta var. antiquorum) characterised by a central corm and edible side cormels. The DL and KW landraces were classified as Dasheen (C. esculenta var. esculenta), characterised by a large edible main corm and smaller side cormels. A bambara groundnut landrace was collected from Jozini, KwaZulu- Natal, and characterised into three selections (‘Red’, ‘Light-brown’ and ‘Brown’) based on seed coat colour. Seed colour was hypothesised to have an effect on seed quality. Field and rainshelter experiments were conducted for both taro and bambara landraces at Roodeplaat in Pretoria and Ukulinga Research Farm in Pietermaritzburg, over two growing seasons (2010/11 and 2011/12). The objective of the field trials for taro and bambara groundnut was to determine mechanisms associated with drought tolerance in taro and bambara groundnut landraces. Experiments were laid out in a split-plot design where irrigation [fully irrigated (FI) and rainfed (RF)] was the main factor and landraces (3 landraces of either taro or bambara groundnut) were sub-factors. Treatments were arranged in a randomised complete block design (RCBD), replicated three times. Rainfed trials were established with irrigation to allow for maximum crop stand. Thereafter, irrigation was withdrawn. Whilst experimental designs and layouts for taro and bambara groundnut were similar, differences existed with regards to plot sizes and plant spacing. Trials were planted on a total land area of 500 m2 and 144 m2, for taro and bambara groundnut, respectively. Plant spacing was 1 m x 1 m for taro and 0.3 m x 0.3 m for bambara groundnut. Irrigation scheduling in the FI treatment was based on ETo and Kc and was applied using sprinkler irrigation system. Separate rainshelter experiments were conducted for taro and bambara groundnut landraces at Roodeplaat, to evaluate growth, yield and water-use of taro and bambara groundnut landraces under a range of water regimes. The experimental design was similar for both crops, a RCBD with two treatment factors: irrigation level [30, 60 and 100% crop water requirement (ETa)] and landrace (3 landraces), replicated three times. Irrigation water was applied using drip irrigation system based on ETo and Kc. Data collection in field and rainshelter trials included time to emergence, plant height, leaf number, leaf area index (LAI), stomatal conductance and chlorophyll content index (CCI). For taro field trials, vegetative growth index (VGI) was also determined. Yield and yield components (harvest index, biomass, corm number and mass) as well as water–use efficiency (WUE) were determined at harvest. Intercropping of taro and bambara groundnut was evaluated under dryland conditions using farmers’ fields at Umbumbulu, KwaZulu–Natal, South Africa. The experimental design was a RCBD replicated three times. Intercrop combinations included taro and bambara groundnut sole crops, a 1:1 (one row taro to one row bambara groundnut) and 1:2 intercrop combinations. The taro UM landrace and ‘Red’ bambara groundnut landrace selection were used in the intercropping study. Lastly, data collected from field and rainshelter experiments were used to develop crop parameters to calibrate and validate the FAO’s AquaCrop model for taro and bambara groundnut landraces. The UM landrace was used for taro while the ‘Red’ landrace selection was used for bambara groundnut. AquaCrop was calibrated using observed data from optimum (FI) experiments conducted during 2010/11. Model validation was done using observations from field and rainshelter experiments conducted during 2011/12 as well as independent data. Results showed that all taro landraces were slow to emerge (≈ 49 days after planting). Stomatal conductance declined under conditions of limited water availability (RF, 60% and 30% ETa). The UM landrace showed better stomatal regulation compared with KW and DL landraces under conditions of limited water availability. Plant growth (plant height, leaf number, LAI and CCI) of taro landraces was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The UM landrace showed moderate reductions in growth compared with the DL and KW landraces, suggesting greater adaptability to water limited conditions. The VGI showed a large reduction in growth under RF conditions and confirmed the UM landrace’s adaptability to limited water availability. Limited water availability (RF, 60% and 30% ETa) resulted in lower biomass, HI, and final yield in taro landraces relative to optimum conditions (FI and 100% ETa). For all trials, the DL landrace failed to produce any yield. WUE of taro landraces was consistent for the three irrigation levels (30, 60 and 100% ETa); however, on average, the UM landrace was shown to have a higher WUE than the KW landrace. Bambara groundnut landraces were slow to emerge (up to 35 days after planting). ‘Red’ and ‘Brown’ landrace selections emerged better than the ‘Light-brown’ landrace selection, confirming the effect of seed colour on early establishment performance. Plant growth (stomatal conductance, CCI, plant height, leaf number, LAI and biomass accumulation) was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The ‘Red’ landrace selection showed better adaptation to stress. Limited water availability resulted in early flowering and reduced flowering duration as well as early senescence and maturity of bambara groundnut landrace selections. The ‘Red’ landrace selection showed delayed leaf senescence under conditions of limited water availability. Yield reductions of up to 50% were observed under water limited conditions (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). Water use efficiency increased at 60% and 30% ETa, respectively, relative to 100% ETa, implying adaptability to limited water availability. The ‘Red’ landrace selection showed better yield stability and WUE compared with the ‘Brown’ and ‘Light-brown’ landrace selections suggesting that seed colour may be used as a selection criterion for drought tolerance in bambara groundnut landraces. The intercropping study showed that intercropping, as an alternative cropping system, had more potential than monocropping. Evaluation of growth parameters showed that taro plant height was generally unaffected by intercropping but lower leaf number was observed as compared with the sole crop. Bambara groundnut plants were taller and had more leaves under intercropping relative to the sole crop. Although not statistically significant, yield was generally lower in the intercrops compared with the sole crops. Evaluation of intercrop productivity using the land equivalent ratio (LER) showed that intercropping taro and bambara groundnut at a ratio of 1:1 was more productive (LER = 1.53) than intercropping at a ratio of 1:2 (LER = 1.23). The FAO’s AquaCrop model was then calibrated for the taro UM landrace and ‘Red’ bambara groundnut landrace selection. This was based on observations from previous experiments that suggested them to be drought tolerant and stable. Calibration results for taro and bambara groundnut landraces showed an excellent fit between predicted and observed parameters for canopy cover (CC), biomass and yield. Model validation for bambara groundnut showed good model performance under field (FI and RF) conditions. Model performance was satisfactory for rainshelters. Validation results for taro showed good model performance under all conditions (field and rainshelters), although the model over-estimated CC for the declining stage of canopy growth under RF conditions. Model verification using independent data for taro showed equally good model performance. In conclusion, the taro UM landrace and ‘Red’ bambara groundnut landrace selection were shown to be drought tolerant and adapted to low levels of water–use. The mechanisms responsible for drought tolerance in the taro UM landrace and ‘Red’ bambara groundnut landrace selection were described as drought avoidance and escape. The taro UM landrace and ‘Red’ bambara groundnut landraces avoided stress through stomatal regulation, energy dissipation (loss of chlorophyll) as well as reducing canopy size (plant height, leaf number and LAI), which translates to minimised transpirational water losses. This indicated landrace adaptability to low levels of water–use. The ‘Red’ bambara groundnut landrace selection showed phenological plasticity and escaped drought by flowering early, delaying leaf senescence, and maturing early under conditions of limited water availability. Performance of the ‘Red’ landrace selection lends credence to the use of seed coat colour as a possible selection criterion for drought tolerance in bambara groundnut, and possibly for other landraces with variegated seed. The taro UM landrace escaped drought by maturing early under conditions of limited water availability. The FAO’s AquaCrop model was successfully calibrated and validated for taro UM and ‘Red’ bambara groundnut landraces. The calibration and validation of AquaCrop for taro is the first such attempt and represents progress in the modelling of neglected underutilised crops. The calibration and validation of AquaCrop for taro requires further fine-tuning while that for bambara groundnut still needs to be tested for more diverse landraces.
Drought tolerance and water-use of selected South African landraces of Taro (Colocasia esculenta L. schott) and Bambara groundnut (Vigna subterranea L. Verdc)
(2012) Mabhaudhi, Tafadzwanashe.; Modi, Albert Thembinkosi.
Issues surrounding water scarcity will become topical in future as global fresh water resources become more limited thus threaten crop production. Predicted climate change and increasing population growth will place more pressure on agriculture to produce more food using less water. As such, efforts have now shifted to identifying previously neglected underutilised species (NUS) as possible crops that could be used to bridge the food gap in future. Taro (Colocasia esculenta L. Schott) and bambara groundnut (Vigna subterranea L. Verdc) currently occupy low levels of utilisation in South Africa. Both crops are cultivated using landraces with no improved varieties available. Information describing their agronomy and water–use is limited and remains a bottleneck to their promotion. The aim of this study was to determine the drought tolerance and water–use of selected landraces of taro and bambara groundnut from KwaZulu-Natal, South Africa. In order to meet the specific objectives for taro and bambara groundnut management, an approach involving conventional and modelling techniques was used. Three taro landraces [Dumbe Lomfula (DL), KwaNgwanase (KW) and Umbumbulu (UM)] were collected from the North Coast and midlands of KwaZulu-Natal, South Africa, in 2010. The UM landrace was classified as Eddoe type taro (C. esculenta var. antiquorum) characterised by a central corm and edible side cormels. The DL and KW landraces were classified as Dasheen (C. esculenta var. esculenta), characterised by a large edible main corm and smaller side cormels. A bambara groundnut landrace was collected from Jozini, KwaZulu- Natal, and characterised into three selections (‘Red’, ‘Light-brown’ and ‘Brown’) based on seed coat colour. Seed colour was hypothesised to have an effect on seed quality. Field and rainshelter experiments were conducted for both taro and bambara landraces at Roodeplaat in Pretoria and Ukulinga Research Farm in Pietermaritzburg, over two growing seasons (2010/11 and 2011/12). The objective of the field trials for taro and bambara groundnut was to determine mechanisms associated with drought tolerance in taro and bambara groundnut landraces. Experiments were laid out in a split-plot design where irrigation [fully irrigated (FI) and rainfed (RF)] was the main factor and landraces (3 landraces of either taro or bambara groundnut) were sub-factors. Treatments were arranged in a randomised complete block design (RCBD), replicated three times. Rainfed trials were established with irrigation to allow for maximum crop stand. Thereafter, irrigation was withdrawn. Whilst experimental designs and layouts for taro and bambara groundnut were similar, differences existed with regards to plot sizes and plant spacing. Trials were planted on a total land area of 500 m2 and 144 m2, for taro and bambara groundnut, respectively. Plant spacing was 1 m x 1 m for taro and 0.3 m x 0.3 m for bambara groundnut. Irrigation scheduling in the FI treatment was based on ETo and Kc and was applied using sprinkler irrigation system. Separate rainshelter experiments were conducted for taro and bambara groundnut landraces at Roodeplaat, to evaluate growth, yield and water-use of taro and bambara groundnut landraces under a range of water regimes. The experimental design was similar for both crops, a RCBD with two treatment factors: irrigation level [30, 60 and 100% crop water requirement (ETa)] and landrace (3 landraces), replicated three times. Irrigation water was applied using drip irrigation system based on ETo and Kc. Data collection in field and rainshelter trials included time to emergence, plant height, leaf number, leaf area index (LAI), stomatal conductance and chlorophyll content index (CCI). For taro field trials, vegetative growth index (VGI) was also determined. Yield and yield components (harvest index, biomass, corm number and mass) as well as water–use efficiency (WUE) were determined at harvest.Intercropping of taro and bambara groundnut was evaluated under dryland conditions using farmers’ fields at Umbumbulu, KwaZulu–Natal, South Africa. The experimental design was a RCBD replicated three times. Intercrop combinations included taro and bambara groundnut sole crops, a 1:1 (one row taro to one row bambara groundnut) and 1:2 intercrop combinations. The taro UM landrace and ‘Red’ bambara groundnut landrace selection were used in the intercropping study. Lastly, data collected from field and rainshelter experiments were used to develop crop parameters to calibrate and validate the FAO’s AquaCrop model for taro and bambara groundnut landraces. The UM landrace was used for taro while the ‘Red’ landrace selection was used for bambara groundnut. AquaCrop was calibrated using observed data from optimum (FI) experiments conducted during 2010/11. Model validation was done using observations from field and rainshelter experiments conducted during 2011/12 as well as independent data. Results showed that all taro landraces were slow to emerge (≈ 49 days after planting). Stomatal conductance declined under conditions of limited water availability (RF, 60% and 30% ETa). The UM landrace showed better stomatal regulation compared with KW and DL landraces under conditions of limited water availability. Plant growth (plant height, leaf number, LAI and CCI) of taro landraces was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The UM landrace showed moderate reductions in growth compared with the DL and KW landraces, suggesting greater adaptability to water limited conditions. The VGI showed a large reduction in growth under RF conditions and confirmed the UM landrace’s adaptability to limited water availability. Limited water availability (RF, 60% and 30% ETa) resulted in lower biomass, HI, and final yield in taro landraces relative to optimum conditions (FI and 100% ETa). For all trials, the DL landrace failed to produce any yield. WUE of taro landraces was consistent for the three irrigation levels (30, 60 and 100% ETa); however, on average, the UM landrace was shown to have a higher WUE than the KW landrace. Bambara groundnut landraces were slow to emerge (up to 35 days after planting). ‘Red’ and ‘Brown’ landrace selections emerged better than the ‘Light-brown’ landrace selection, confirming the effect of seed colour on early establishment performance. Plant growth (stomatal conductance, CCI, plant height, leaf number, LAI and biomass accumulation) was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The ‘Red’ landrace selection showed better adaptation to stress. Limited water availability resulted in early flowering and reduced flowering duration as well as early senescence and maturity of bambara groundnut landrace selections. The ‘Red’ landrace selection showed delayed leaf senescence under conditions of limited water availability. Yield reductions of up to 50% were observed under water limited conditions (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). Water use efficiency increased at 60% and 30% ETa, respectively, relative to 100% ETa, implying adaptabilityto limited water availability. The ‘Red’ landrace selection showed better yield stability and WUE compared with the ‘Brown’ and ‘Light-brown’ landrace selections suggesting that seed colour may be used as a selection criterion for drought tolerance in bambara groundnut landraces. The intercropping study showed that intercropping, as an alternative cropping system, had more potential than monocropping. Evaluation of growth parameters showed that taro plant height was generally unaffected by intercropping but lower leaf number was observed as compared with the sole crop. Bambara groundnut plants were taller and had more leaves under intercropping relative to the sole crop. Although not statistically significant, yield was generally lower in the intercrops compared with the sole crops. Evaluation of intercrop productivity using the land equivalent ratio (LER) showed that intercropping taro and bambara groundnut at a ratio of 1:1 was more productive (LER = 1.53) than intercropping at a ratio of 1:2 (LER = 1.23). The FAO’s AquaCrop model was then calibrated for the taro UM landrace and ‘Red’ bambara groundnut landrace selection. This was based on observations from previous experiments that suggested them to be drought tolerant and stable. Calibration results for taro and bambara groundnut landraces showed an excellent fit between predicted and observed parameters for canopy cover (CC), biomass and yield. Model validation for bambara groundnut showed good model performance under field (FI and RF) conditions. Model performance was satisfactory for rainshelters. Validation results for taro showed good model performance under all conditions (field and rainshelters), although the model over-estimated CC for the declining stage of canopy growth under RF conditions. Model verification using independent data for taro showed equally good model performance. In conclusion, the taro UM landrace and ‘Red’ bambara groundnut landrace selection were shown to be drought tolerant and adapted to low levels of water–use. The mechanisms responsible for drought tolerance in the taro UM landrace and ‘Red’ bambara groundnut landrace selection were described as drought avoidance and escape. The taro UM landrace and ‘Red’ bambara groundnut landraces avoided stress through stomatal regulation, energy dissipation (loss of chlorophyll) as well as reducing canopy size (plant height, leaf number and LAI), which translates to minimised transpirational water losses. This indicated landrace viii adaptability to low levels of water–use. The ‘Red’ bambara groundnut landrace selection showed phenological plasticity and escaped drought by flowering early, delaying leaf senescence, and maturing early under conditions of limited water availability. Performance of the ‘Red’ landrace selection lends credence to the use of seed coat colour as a possible selection criterion for drought tolerance in bambara groundnut, and possibly for other landraces with variegated seed. The taro UM landrace escaped drought by maturing early under conditions of limited water availability. The FAO’s AquaCrop model was successfully calibrated and validated for taro UM and ‘Red’ bambara groundnut landraces. The calibration and validation of AquaCrop for taro is the first such attempt and represents progress in the modelling of neglected underutilised crops. The calibration and validation of AquaCrop for taro requires further fine-tuning while that for bambara groundnut still needs to be tested for more diverse landraces.
Estimating water use and yield of soybean (glycine max) under mulch and fertilizer in rainfed conditions in KwaZulu-Natal.
(2017) Lembede, Lungile Phumelele.; Kunz, Richard Peter.; Mabhaudhi, Tafadzwanashe.
South Africa is classified as a semi-arid country characterized by low and erratic rainfall. This poses major limitations to crop productivity, especially for smallholder farmers who rely on rainfed agriculture. This is worsened by lack of knowledge regarding best management practices that can improve crop yields attained by smallholder farmers. In addition, smallholder farmers lack access to markets and do not participate in the agricultural value chain. The Biofuel Regulatory Framework (DoE, 2014) seeks to include smallholder farmers in the biofuel feedstock value chain. However, a prerequisite to their meaningful participation in the value chain would be to increase their current levels of crop and water productivity. The main aim of this study was to estimate the yield and water use of soybean (Glycine max L.) under rainfed and smallholder farming conditions using the AquaCrop model. Secondary to this, the effect of mulch and fertilizer on soybean water use efficiency was assessed. Lastly, the Soil Water Balance model (SWB) was used to compare simulations made by AquaCrop for the non-mulched, full fertilizer treatment. Thereafter, the water use efficiency of soybean was calculated from crop water use and the final yield. The soybean trial was carried out at Swayimane, KwaZulu-Natal. The model simulations of crop water use and reference crop evapotranspiration were also used to calculate crop coefficients under non-standard conditions. Crop growth and yield parameters were measured to calibrate and evaluate model performance. Soil water content was monitored using Watermark sensors, along with climatic variables. An analysis of variance (ANOVA) was used to detect significant interactions between treatments, while statistical indicators were used to evaluate model performance of AquaCrop and the SWB model. Mulching improved soil water content and reduced soil water evaporation, although the final yield and total water use efficiency was reduced. It is believed the yield reduction in mulched plots was mostly affected by nitrogen immobilization as a result of decaying straw mulch. Increasing soil fertility improved crop yield and water use efficiency in both mulched and non-mulched treatments. The AquaCrop model simulated the final yield and biomass fairly well, except in mulched treatments. The model simulated the highest yield in the mulched, fully fertilized plots, which is contrary to what was observed. This is because the model only accounts for improved soil water content and does not account for the complex interactions between the soil and mulch residue that resulted in nitrogen deficiency. The SWB model simulated fairly similar crop water use and yield to AquaCrop. The water use efficiencies obtained in this study were compared to that derived by Mengistu et al. (2014) for the same cultivar grown in a commercial farming environment at Baynesfield, KwaZulu-Natal. In comparison to commercial farmers, smallholder farmers tend to produce lower water use efficiencies. The modelled water use efficiency reported for Baynesfield was 1.277 kg m-3, compared to 0.359 kg m-3 obtained in this study for the non-mulched, full fertilizer treatment. According to AquaCrop, the mulched, full fertilizer treatment had a water use efficiency of 0.485 kg m-3. It is believed that the latter water use efficiency could have been achieved had enough nitrogen been available to the crop. In conclusion, implementing best management practices can help narrow the yield gap between smallholder and commercial farmers. It was evident from this study and others that agronomic practices have a significant impact on crop yield and ultimately, water use efficiency.
Estimation of water use efficiency of soybean (glycine max) for biodiesel production in KwaZulu-Natal.
(2020) Reddy, Kyle Trent Cameron.; Kunz, Richard Peter.; Mabhaudhi, Tafadzwanashe.
Abstract available in pdf.
An evaluation of the factors that influence households’ participation and perceptions of the tree and ecological restoration in the eThekwini District, South Africa.
(2022) Soni, Siphelele Goodenough.; Mudhara, Maxwell.; Mabhaudhi, Tafadzwanashe.
Ecological restoration, described as the method of assisting the regeneration of an ecosystem that has been degraded, weakened, or lost is an important tool for achieving conservation objectives. Concern for the environment is expanding as a result of increased environmental damage brought on by human activity. Without knowing how people perceive the environment, effective environmental management cannot be achieved. Interactions between people and nature are frequently influenced by their beliefs, perceptions, and environmental concerns. The effectiveness of ecological restoration is seen as being largely dependent on community participation. Understanding factors influencing households’ perceptions and participation in restoration assists restoration managers in creating ecological restoration programs that encourage community participation. Hence this study evaluated socioeconomic and demographic factors influencing household perceptions and participation in the tree and ecological restoration in eThekwini Districts, South Africa. Primary data were collected from 160 randomly selected household heads. Multinomial logistic regression was utilized to evaluate the factors influencing households’ decision to participate in the tree and ecological restoration. The results showed that socioeconomic and demographic factors such as age (p<0.000), gender (p<0.030), years of education (p<0.000), and total monthly income (p<0.077) statistically significantly influence participation positively, whereas household tenure (p<0.012) affects negatively. Ordinal logistic regression was utilized to determine the socioeconomic factors and household demographic characteristics influencing households’ perceptions towards trees in their environment. The results showed that socioeconomic factors and household demographic characteristics such as age (p<0.000), gender (p<0.020), marital status (p<0.023) and dwelling type (p<0.007) were significant predictors of households’ perceptions towards trees in their environment. Principal component analysis (PCA) was used to generate composite indices representing perceived income from the ecological restoration projects. Ordinary Least Squares was then employed to determine the factors influencing such valuation of the ecological restoration project. The model showed that socioeconomic and demographic factors such as age (p<0.000), gender (p<0.060), total monthly income (p<0.039), years of education (p<0.001), household size (p<0.073) and access to forest resources (p<0.032) influence obtained income from the restoration project. The study concludes that socioeconomic and demographic elements, which were very important in the research area, should be incorporated into the government policy framework on ecological restoration projects. These factors could encourage local people's involvement in ecological restoration projects if they are thoughtfully incorporated into policy formulation. Keywords: Ecological restoration, socioeconomic factors, demographic factors, community participation, environmental concerns, household perceptions.
From niche to mainstream: creating a policy environment for the proliferation of non-staple whole grains in South Africa.
(2023) Ndebele, Thalente.; Ngidi, Mjabuliseni Simon Cloapas.; Mabhaudhi, Tafadzwanashe.; Walton, Stephanie.
Over the centuries, non-staple agricultural commodities have been produced in limited quantities and are generally neglected yet bear a significant untapped potential. Preoccupation with staple grains has constrained the production of non-staple whole grains, and it remains fascinating to explore the barriers, and reluctance to shift toward non-staple crops. Admissibly, the contribution of these grains (sorghum, millet, oats, barley, and other wheat varieties) to the gross value of agriculture is hardly ever known. The nutritional and environmental benefits and other uses remain unexplored. To an extent, they are now mainly used for non-food purposes (brewery and industrial uses) contrary to being used as a source of food for human beings. The study assesses the functioning of the value chain of the non-staple wholegrains in South Africa. The study used both primary and secondary data to understand the functioning of the non-staple value chain. A qualitative method was employed to collect data from the provinces of the Western Cape (Overberg, West Coast), Gauteng (Johannesburg, Pretoria), and North West (Taung). For primary data, a snowballing sampling procedure was used to select 25 respondents involved in the non-staple grain value chain. These participants included smallholder farmers, processors/traders (silo-owners), private/public extension and information organisations, policy organisations, landowners, input suppliers and financers (insurers). While Semistructured questionnaires were used to conduct interviews. Desktop analysis was used to retrieve and analyse food policies relating to non-staple grains. A diagnostic research design was employed for analysis. Extension carousel, influence diagram, graph theory, policy map and Venn diagram were employed to analyse data, locate the leverage points, and track stakeholders’ influence on each other which inevitably affects the production scale of nonstaple wholegrains. Three specific objectives were explored in this study. The first specific objective was to assess the extent to which emerging farmers in the wholegrain economies are pressured or incentivised by policies and other actors in the network. The second was to determine points of tension within grains networks where the potential for the proliferation of emerging wholegrains economies is curtailed. The third specific objective3 was to identify the policies that can enable the proliferation of new wholegrain economies and their ability to successfully increase production and access to ensure environmental, nutritional and equity objectives are met. Results from the extension carousel demonstrated that the farmers’ participation in the type of grains they are involved in is influenced by the commodity supply and demand. Since market information is mainly about staple grains, this automatically create bias towards participation in the staple grain than non-staple grains. The results revealed that access to land is a challenge for the smallholder, previously disadvantaged farmers who are given a smallsized land for grain production. The respondents indicated this is because the preference is given to livestock farmers and profit-orientated commodity growers. Some factors contributing to an unconducive environment for non-staple grain farmers include ever-increasing high input costs; lack of comprehensive support systems like incentives and subsidies to protect farmers from price fluctuations, and input unavailability due to domestic transportation difficulties and input shortages. Additionally, while there is a commitment to help farmers purchase or lease machinery and other technological equipment, it is either delivered late or unavailable from international suppliers. Other challenges that cause difficulties for non-staple wholegrain farmers and set them back are finance-related policies, grain pricing, and limited markets. Results illustrated that smallholder farmer’s access to finance is a challenge not only because they lack collateral to secure loans due to eligibility criteria, interest rates, and repayment plans (terms/ conditions). Findings also showed that grains like oats have a limited market (fewer buyers), whereas barley is climatically risky, which also causes farmers to be reluctant to produce non-staple grains. Results also revealed that stakeholders’ relationships maintain the status quo of being biased toward staple grains. This includes market agents sensitizing farmers to determine grain choice, production quantities, and market choice. Shortage of input (fertilisers, machinery) influence farmers to deprioritize conservation measures. Landowners influence grain farmers not to continue growing non-staple wholegrain and shift to staple export orientated commodities. Investors influence the developmental financers’ approach and conditions. The study concludes that landowners, investors, market agents, and financers influence farmers’ decision to grow non-staple wholegrain. The bottlenecks in the non-staple whole grain value chain were lack of support for non-staple grain farmers, limited market access, unfavourable terms and conditions of available funding opportunities, limited access to land, ill-structured coordination, communication, and transformation. Some policies that could strengthen the participation of non-staple whole grain farmers in the value include land policy, farm subsidy policy, tax incentive policy, funding framework, and equity policy. There is a need to realign and synergize the goals of the different actors to favour all grains equally. More attention needs to be given to neglected non-staple grains. Food-related policies need to be reviewed to reflect the importance of non-staple wholegrain.
Identification of cowpea (vigna unguiculata (L) (walp) genotypes and genetic improvement for enhanced yield and nutritional quality.
(2023) Gumede, Mbali Thembi.; Mabhaudhi, Tafadzwanashe.; Gerrano, Abe Shegro.
Cowpea (Vigna unguiculata (L.) Walp) is a staple legume crop with potential to address food insecurity and malnutrition in the Sub-Saharan Africa (SSA). It is also among the neglected underutilized legume crop species in the region. The crop’s yield production has never met the potential yields of the crop in the SSA. In addition, given its nutritional value, ability to withstand extreme environmental conditions, nitrogen fixation ability and its greater potential to address nutrient deficiencies and food insecurity in the SSA. These attributes make cowpea an ideal crop to sustainable future for the people and environment. There is a need to develop cowpea varieties that are high yielding with high nutritional values to combat food insecurity. Therefore, the objectives of the study were: (1) to assess the genotype by environment interaction effect and select cowpea genotypes with high grain yield and adaptation across selected cowpea growing environments in South Africa, (2) to assess the phenotypic variability and correlation analysis in cowpea based on yield and yield related traits, (3) to evaluate the variations of nutritional content and phytochemical compositions among cowpea genotypes under diverse environments, (4) to assess the genetic diversity among cowpea genotypes using single nucleotide polymorphism (SNP) markers, and to select distinct and complementary genotypes for developing improved cultivars and (5) to determine the combining ability effects and gene action controlling the yield and yield-related traits among selected cowpea parental genotypes and their progenies. The first study assessed the extent of genotype by environment interaction (GEI) of cowpea genotype to the influence of genotype (G), environment (E) and their interaction (GEI) effects on grain yield in cowpea and to assess the stability of cowpea genotypes to identify stable and high-yielding genotypes for broad or narrow adaptation to improve cowpea productivity in South Africa and identify the identical agro-ecologies using analysis of variance (ANOVA), additive main effects and multiplicative interaction (AMMI) and the genotype-by-environment interaction (GGE) biplot analyses. The AMMI ANOVA showed the significant GEI effect which accounted for 57% variation, whereas genotype and environment main effects accounted for 29% and 13% variation, respectively. The AMMI stability values (ASV) analysis identified genotype Acc-Cowp44 as the most stable genotype recording the lowest ASV of 0.03. The biplot depicted eight sectors and environments were clustered into three of the eight sector whereby E4 (Brits 2020/2021), E5 (Loskop 2020/2021), E6 (Mafikeng 2020/2021) and E7 (Polokwane 2020/2021) which formed a mega-environment and the second sector which involved environments E1 (Brits 2019/2020), E2 (Loskop 2019/2020) and E3 (Roodeplaat 2019/2020) formed one mega-environment. The cowpea genotypes Acc-Cowp38, Acc-Cowp2, Acc-Cowp9, Acc-Cowp5 and Acc-Cowp39 were identified as ideal for grain yield, in that order. These genotypes are recommended for production in South Africa or in similar agroecologies, and for incorporation in future breeding programs targeting genetic improvement for grain yield. The second study assessed 50 cowpea genotypes using yield and yield components to determine the phenotypic correlations among them and selection of best performing genotypes among tested genotypes for enhanced cultivar development. The study revealed the significant differences at 5% and 1% level of probability among the assessed grain yield and yield component traits. The study further indicates that number of pods per plant (NPP), pod length (PL), number of seeds per pod (NSP) and hundred seed weight (HSW) had significant and positive correlations with grain yield, therefore these traits can be used as a proxy trait for increased grain yield. Similarly, the principal component analysis (PCA) biplot identified number of branches (NB), number of pods per plant (NPP), pod length (PL), pod width (PW), number of seeds per pod (NSP), and hundred seed weight (HSW) as the important traits in the production of grain yield. Genotypes Acc-Cowp2, 98K_5301, Acc-Cowp4, Acc-Cowp17 and Acc-Cowp9 were grouped together based on their high exhibition of NPP, PW, NSP, PL, HSW and grain yield (GY). The selected genotypes could be considered as potential sources of gene to improve these traits and could serve as parental genotypes in breeding programs targeting enhanced high-yielding varieties. The third study assessed the nutritional and phytochemical traits among the 50 cowpea genotypes to select superior lines with high nutritional compositions for cultivar development for nutritional quality. The study highlighted the significant effects for all nutritional and phytochemical traits for genotype, environment, and genotype by environment interaction evaluated except for flavonoids and fat content. Genotypes Acc-Cowp6, Acc-Cowp17, Acc- Cowp14, 98K_5301, Acc-Cowp9, Acc-Cowp32, Acc-Cowp9, Acc-Cowp4, Acc-Cowp16 and Acc-Cowp21 were selected based on high concentration of Ca, Mg, P, Na and Zn. Genotype Acc-Cowp31 and Acc-Cowp13 were highly associated with protein content while genotype Acc-Cowp39 were in close association with fat content. Further, genotypes Acc-Cowp34, Acc- Cowp18, Acc-Cowp48, Acc-Cowp22, Acc-Cowp26, Acc-Cowp49 and Acc-Cowp28 had low concentrations of total phenolic, flavonoids and condensed tannins. The fourth study used 90 genetically diverse cowpea to assess the magnitude of the genetic diversity and population structure among cowpea genotypes using single nucleotide polymorphisms (SNP) markers. The study revealed that 49% of the selected SNP markers were highly polymorphic and efficiently discriminate the tested cowpea accessions. The low heterozygosity and the high inbreeding coefficients observed among cowpea varieties indicate that the accessions reached an acceptable level of homozygosity. The model-based (structure analysis) and distance-based (UPGM) clustering approaches were used in this study. The model-based analysis revealed the presence of four subpopulations at K = 4 whereas the distance-based cluster analysis classified the cowpea accessions into three distinct clusters. The subpopulations identified exhibited a high level of genetic diversity and were moderately differentiated. This result suggests that the accessions studied are unique and have greater potential to contribute to new varieties for breeding programs in South Africa. The fifth study determined the combining ability effects and gene action controlling the yield and its related traits among 10 selected parental genotypes and 45 crosses using the half diallel mating design. There were significant genotypic, environmental and their interaction effects for almost all traits except leaf length (LL) and number of seeds per pod (NSP) exhibited by both parental genotypes and their progenies. The GCA effects were significant for LW, PL, NSP and HSW whereas the SCA effects were significant for pod width (PW) only. The GCA x environmental interaction effects were highly significant for all traits while the SCA x environmental interaction effects were significant for all the traits except plant height (PH) and LL. The parents Acc-cowp17, Acc-cowp31, Acc-cowp9, Acc-cowp5, Acc-cowp38 and Acccowp19 were identified as good combiners for grain yield and its associated traits productivity. The newly developed progenies Acc-Cowp31 x Acc-Cowp5, Acc-Cowp38 x Acc-Cowp19, Acc-Cowp9 x Acc-Cowp2, Acc-Cowp47 x Acc-Cowp9, Acc-Cowp31 x Acc-Cowp9, Acc- Cowp32 x Acc-Cowp9, Acc-Cowp47 x Acc-Cowp38, and Acc-Cowp17 x Acc-Cowp38 were found to be the best performing due to their desirable SCA effects for enhanced grain yield. The study revealed that trait expression was controlled by both additive and non-additive effect with the additive gene action shown to be the important in controlling traits including NB, LW, NPP, NSP and HSW.
Impact of crop productivity and market participation on rural households’ food and nutrition security status: the case of Mpumalanga and Limpopo provinces, South Africa.
(2022) Hlatshwayo, Simphiwe Innocentia.; Ngidi, Mjabuliseni Simon Cloapas.; Modi, Albert Thembinkosi.; Temitope, Olumuyiwa Ojo.; Mabhaudhi, Tafadzwanashe.
The agricultural sector has proven to be the backbone of improving rural households’ food security and livelihoods in developing countries. However, the sector faces numerous challenges, such as insufficient access to technology, institutional difficulties, inappropriate policies, poor infrastructure, and unsuccessful links to the markets, making it difficult for smallholder farmers to participate in the formal market sector. Smallholder farmers in South Africa are still trapped in low-productivity traditional technologies that have a negative impact on output and livelihoods. Low agricultural productivity and lack of market access threaten the efforts of alleviating poverty and improving food security. The study's main objective is to analyse the impact of crop productivity and market participation on rural households’ food and nutrition. The specific objectives were to assess the determinants and intensity of market participation among smallholder farmers; estimate the impact of market participation on the food and nutrition security status of the smallholder farmers; analyse the factors affecting crop productivity among smallholder farmers, and evaluate the effect of crop productivity on household food and nutrition security status in the study area. The study used secondary data, which was collected from a total of 1520 respondents who were selected through stratified random sampling. The study focused on two provinces (Mpumalanga and Limpopo) in South Africa, based on the predominance of smallholder farmers. While assessing the determinants and intensity of market participation among smallholder farmers, the results of the DH estimation model show that the gender of the household head, family member working on the farm, wealth index, and agricultural assistance, age of household head and family member with HIV were statistically significant factors influencing market participation. The result from the second hurdle showed that the perceived intensity of market participation was influenced by marital status, educational level of the household head, wealth index, access to agricultural assistance, household size, household age, and family member with HIV. The study also analysed the effect of market participation on the food security of smallholder farmers. The household food insecurity access scale (HFIAS) results revealed that out of the total sample size, 85% of the households were food insecure while 15% were food secure. The gender of the household head, receiving social grants, wealth index, and having a family member with HIV significantly influenced farmers’ market participation. The results of the extended ordered probit regression model showed that household size, having a family member with HIV, agricultural assistance, educational level of household head, ownership of livestock, age of household head, gender of household head, and having access to social grants variables were statistically influencing the food insecurity situation of smallholder farmers. The Household Dietary Diversity Score (HDDS) showed that in the overall sampled population, 57% of smallholder farmers had the highest dietary diversity, followed by medium dietary diversity (25%), and the lowest dietary diversity was 18%. The t-test results showed that farmers who participated in the market enjoyed higher HDDS than those who did not participate in the market. The Food Consumption Score (FCS) showed that in the overall population, the acceptable FCS was 54%, followed by a borderline food consumption score of 30%, and the poor food consumption score was the least at 16%. The gender of the household head, receiving social grants, and the wealth index significantly influenced farmers’ market participation. The results from Poisson endogenous treatment effect model showed that the nutrition status of smallholder farmers was statistically influenced by agricultural assistance, access to market information, household size, ownership of livestock, access to social grants, wealth index, and involvement in crop production variables. The result from the ordered logistic regression model showed that household size had a negative and significant impact on the food consumption score of smallholder farmers. Gender of household head, irrigation type, social grant, and amount harvested had a positive and significant effect on the food consumption score of smallholder farmers. The results from the Tobit regression model showed crop productivity of smallholder farmers was significantly influenced by the gender of the household head, irrigation system, a family member with HIV, involvement in crop production, access to agricultural assistance, and wealth index of smallholder farmers variables. Lastly, the study determined the impact of crop productivity on household food and nutrition security status in the study areas. The results from the CMP model showed that ownership of livestock, harvest, disability in the family, household size, and gender statistically influenced the food (in)security of smallholder farmers. The results also showed that social grants, agricultural assistance, harvest, and household size significantly impacted the nutrition status of smallholder farmers. The results from this study support the findings of many previous studies conducted in developing countries and show that more intervention is still needed. It is recommended that government, researchers, policy makers, and other stakeholders work together to close the existing gaps between research, policies, programmes, and extension services directed to smallholder farmers. This will help to improve crop productivity and market participation of smallholder farmers, which will, in turn, enhance their food and nutrition security.
Impact of crop productivity and market participation on rural households’ food and nutrition security status: the case of Mpumalanga and Limpopo provinces, South Africa.
(2022) Hlatshwayo, Simphiwe Innocentia.; Ngidi, Mjabuliseni Simon Cloapas.; Ojo, Temitope Oluwaseun.; Modi, Albert Thembinkosi.; Mabhaudhi, Tafadzwanashe.;
The agricultural sector has proven to be the backbone of improving rural households’ food security and livelihoods in developing countries. However, the sector faces numerous challenges, such as insufficient access to technology, institutional difficulties, inappropriate policies, poor infrastructure, and unsuccessful links to the markets, making it difficult for smallholder farmers to participate in the formal market sector. Smallholder farmers in South Africa are still trapped in low-productivity traditional technologies that have a negative impact on output and livelihoods. Low agricultural productivity and lack of market access threaten the efforts of alleviating poverty and improving food security. The study's main objective is to analyse the impact of crop productivity and market participation on rural households’ food and nutrition. The specific objectives were to assess the determinants and intensity of market participation among smallholder farmers; estimate the impact of market participation on the food and nutrition security status of the smallholder farmers; analyse the factors affecting crop productivity among smallholder farmers, and evaluate the effect of crop productivity on household food and nutrition security status in the study area. The study used secondary data, which was collected from a total of 1520 respondents who were selected through stratified random sampling. The study focused on two provinces (Mpumalanga and Limpopo) in South Africa, based on the predominance of smallholder farmers. While assessing the determinants and intensity of market participation among smallholder farmers, the results of the DH estimation model show that the gender of the household head, family member working on the farm, wealth index, and agricultural assistance, age of household head and family member with HIV were statistically significant factors influencing market participation. The result from the second hurdle showed that the perceived intensity of market participation was influenced by marital status, educational level of the household head, wealth index, access to agricultural assistance, household size, household age, and family member with HIV. The study also analysed the effect of market participation on the food security of smallholder farmers. The household food insecurity access scale (HFIAS) results revealed that out of the total sample size, 85% of the households were food insecure while 15% were food secure. The gender of the household head, receiving social grants, wealth index, and having a family member with HIV significantly influenced farmers’ market participation. The results of the extended ordered probit regression model showed that household size, having a family member with HIV, agricultural assistance, educational level of household head, ownership of livestock, age of household head, gender of household head, and having access to social grants variables were statistically influencing the food insecurity situation of smallholder farmers. The Household Dietary Diversity Score (HDDS) showed that in the overall sampled population, 57% of smallholder farmers had the highest dietary diversity, followed by medium dietary diversity (25%), and the lowest dietary diversity was 18%. The t-test results showed that farmers who participated in the market enjoyed higher HDDS than those who did not participate in the market. The Food Consumption Score (FCS) showed that in the overall population, the acceptable FCS was 54%, followed by a borderline food consumption score of 30%, and the poor food consumption score was the least at 16%. The gender of the household head, receiving social grants, and the wealth index significantly influenced farmers’ market participation. The results from Poisson endogenous treatment effect model showed that the nutrition status of smallholder farmers was statistically influenced by agricultural assistance, access to market information, household size, ownership of livestock, access to social grants, wealth index, and involvement in crop production variables. The result from the ordered logistic regression model showed that household size had a negative and significant impact on the food consumption score of smallholder farmers. Gender of household head, irrigation type, social grant, and amount harvested had a positive and significant effect on the food consumption score of smallholder farmers. The results from the Tobit regression model showed crop productivity of smallholder farmers was significantly influenced by the gender of the household head, irrigation system, a family member with HIV, involvement in crop production, access to agricultural assistance, and wealth index of smallholder farmers variables. Lastly, the study determined the impact of crop productivity on household food and nutrition security status in the study areas. The results from the CMP model showed that ownership of livestock, harvest, disability in the family, household size, and gender statistically influenced the food (in)security of smallholder farmers. The results also showed that social grants, agricultural assistance, harvest, and household size significantly impacted the nutrition status of smallholder farmers. The results from this study support the findings of many previous studies conducted in developing countries and show that more intervention is still needed. It is recommended that government, researchers, policy makers, and other stakeholders work together to close the existing gaps between research, policies, programmes, and extension services directed to smallholder farmers. This will help to improve crop productivity and market participation of smallholder farmers, which will, in turn, enhance their food and nutrition security.
Moistube Irrigation characterisation and yield response of canola (Brassica napus) under varied Moistube Irrigation.
(2021) Dirwai, Tinashe Lindel.; Senzanje, Aidan.; Mabhaudhi, Tafadzwanashe.
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