Search

Due to global climate change, droughts are likely to become more frequent and more severe in many regions such as in South Africa. In Limpopo, observed high climate variability and projected future climate change will likely increase future maize production risks. This paper evaluates drought patterns in Limpopo at two representative sites. We studied how drought patterns are projected to change under future climatic conditions as an important step in identifying adaptation measures (e.g., breeding maize ideotypes resilient to future conditions). Thirty-year time horizons were analyzed, considering three emission scenarios and five global climate models. We applied the WOFOST crop model to simulate maize crop growth and yield formation over South Africa's summer season. We considered three different crop emergence dates. Drought indices indicated that mainly in the scenario SSP5-8.5 (2051–2080), Univen and Syferkuil will experience worsened drought conditions (DC) in the future. Maize yield tends to decline and future changes in the emergence date seem to impact yield significantly. A possible alternative is to delay sowing date to November or December to reduce the potential yield losses. The grain filling period tends to decrease in the future, and a decrease in the duration of the growth cycle is very likely. Combinations of changed sowing time with more drought tolerant maize cultivars having a longer post-anthesis phase will likely reduce the potential negative impact of climate change on maize. [ABSTRACT FROM AUTHOR]

Maize production in South Africa is concentrated in its central provinces. The Eastern Cape contributes less than 1% of total production, but is steadily increasing its production and has been identified as a priority region for future growth. In this study, we surveyed ear rots at maize farms in the Eastern Cape, and mycotoxins were determined to be present in collected samples. Fungal isolations were made from mouldy ears and species identified using morphology and DNA sequences. Cladosporium, Diplodia, Fusarium and Gibberella ear rots were observed during field work, and of these, we collected 78 samples and isolated 83 fungal strains. Fusarium was identified from Fusarium ear rot (FER) and Gibberella ear rot (GER) and Stenocarpella from Diplodia ear rot (DER) samples, respectively. Using LC-MS/MS multi-mycotoxin analysis, it was revealed that 83% of the collected samples contained mycotoxins, and 17% contained no mycotoxins. Fifty percent of samples contained multiple mycotoxins (deoxynivalenol, 15-acetyl-deoxynivalenol, diplodiatoxin and zearalenone) and 33% contained a single mycotoxin. Fusarium verticillioides was not isolated and fumonisins not detected during this survey. This study revealed that ear rots in the Eastern Cape are caused by a wide range of species that may produce various mycotoxins. [ABSTRACT FROM AUTHOR]

Food self-sufficiency is an important contributor to food security, and one of the potential solutions to this problem is increased food production productivity through agricultural biotechnology. In this paper, we study the relationship between a country's genetically modified (GM) food policy and the food self-sufficiency rate (SSR) under conflicting interests, with the example of GM crop regulation and GM maize production in South Africa. We develop a theoretical model of a small open economy and investigate the GM food policy as the outcome of a GM and a non-GM food groups' lobbying game that follows the model of Grossman and Helpman. The government maximises its payoff by considering the weighted sum of social welfare and contributions from interest groups. Our findings suggest that a lower GM food regulation supports domestic agricultural production, and we offer potential reasons why a country that has a low SSR still has a strict GM food policy regulation. We also find that the food SSR is a biased measure of food availability when both production and consumption change simultaneously. [ABSTRACT FROM AUTHOR]

South Africa (SA) is a leading exporter of maize in Africa. The commercial maize farming sector contributes to about 85% of the overall maize produced. More than 33% of South Africa's population live in rural settlements, and their livelihoods depend entirely on subsistence farming. The subsistence farming system promotes fungal growth and mycotoxin production. This review aims to investigate the exposure levels of the rural population of South Africa to dietary mycotoxins contrary to several reports issued concerning the safety of South African maize. A systematic search was conducted using Google Scholar. Maize is a staple food in South Africa and consumption rates in rural and urban communities are different, for instance, intake may be 1–2 kg/person/day and 400 g/person/day, respectively. Commercial and subsistence maize farming techniques are different. There exist differences influencing the composition of mycotoxins in food commodities from both sectors. Depending on the levels of contamination, dietary exposure of South Africans to mycotoxins is evident in the high levels of fumonisins (FBs) that have been detected in SA home-grown maize. Other potential sources of exposure to mycotoxins, such as carryover effects from animal products and processed foods, were reviewed. The combined effects between FBs and aflatoxins (AFs) have been reported in humans/animals and should not be ignored, as sporadic breakouts of aflatoxicosis have been reported in South Africa. These reports are not a true representation of the entire country as reports from the subsistence-farming rural communities show high incidence of maize contaminated with both AFs and FBs. While commercial farmers and exporters have all the resources needed to perform laboratory analyses of maize products, the greater challenge in combatting mycotoxin exposure is encountered in rural communities with predominantly subsistence farming systems, where conventional food surveillance is lacking. [ABSTRACT FROM AUTHOR]

Grain marketing is complex because important decisions are made on the timing of sales and the quantities sold at every trading activity. The literature suggest various grain-hedging strategies, however these strategies are not adaptable to changing market conditions or are difficult for a producer to implement. To address these limitations, our study developed tailor-made moving average crossover (MAC) strategies that are adaptable to changing market conditions and can be easily followed by risk neutral and risk averse grain producers. The study used daily closing prices for the white maize May futures contract for the period 2009/2010 to 2019/2020. An optimization model was solved using the evolutionary algorithm embedded in Excel® to identify the optimal MAC strategy that maximizes the margin above marketing cost for a risk aversion level. The results showed that optimal MAC strategies differ amongst producers with different levels of risk aversion. Furthermore, it was found that the risk-averse producers perform best by marketing their grain early in the marketing season. Meanwhile, the risk-neutral producers perform better by spreading their marketing activities throughout the season. The results further showed that the optimal MAC strategies performed better than the previously proposed routine strategies. The conclusion is therefore that an optimal MAC strategy outperforms routine strategies because of its ability to adapt to changing market conditions, while still being easy to implement. [ABSTRACT FROM AUTHOR]

Root phenotypes regulate soil resource acquisition; however, their genetic control and phenotypic plasticity are poorly understood. We hypothesized that the responses of root architectural phenes to water deficit (stress plasticity) and different environments (environmental plasticity) are under genetic control and that these loci are distinct. Root architectural phenes were phenotyped in the field using a large maize association panel with and without water deficit stress for three seasons in Arizona and without water deficit stress for four seasons in South Africa. All root phenes were plastic and varied in their plastic response. We identified candidate genes associated with stress and environmental plasticity and candidate genes associated with phenes in well-watered conditions in South Africa and in well-watered and water-stress conditions in Arizona. Few candidate genes for plasticity overlapped with those for phenes expressed under each condition. Our results suggest that phenotypic plasticity is highly quantitative, and plasticity loci are distinct from loci that control phene expression in stress and non-stress, which poses a challenge for breeding programs. To make these loci more accessible to the wider research community, we developed a public online resource that will allow for further experimental validation towards understanding the genetic control underlying phenotypic plasticity. [ABSTRACT FROM AUTHOR]

Abstract: One‐hundred maize samples were analyzed for fungal contamination using conventional and molecular methods. The percentage incidence of different genera isolated revealed the predominance of Fusarium (82%), Penicillium (63%), and Aspergillus species (33%) compared to other genera. Fusarium occurred in 90% and 74% of small scale and commercial samples, respectively, while Penicillium occurred in small scale and commercial samples at an incidence rate of 64% and 62%, respectively. However, among the species, Fusarium verticilloides have the highest incidence of 70% and 76% in commercial and small‐scale maize, respectively, while Penicillium digitatum has 56% total incidence. Aspergillus fumigatus (27%) were also the most dominant of these genera. Fungal genera isolated included Alternaria and Cladosporium although occurring at a lower incidence level of 30%, 32% and 16%, 20%, respectively, in small‐scale and commercial samples. The results emphasize that farmers and consumers should be alerted to the danger of fungal contamination in maize. [ABSTRACT FROM AUTHOR]

Conventional threshold models of price transmission allow for different speeds of adjustment to equilibria depending on the magnitude of price differentials between markets. However, these models typically assume only one underlying long-run equilibrium price relationship. In this article we develop a framework for allowing multiple equilibria and multiple speeds of adjustment with regime separation depending on the magnitude of trade flows between regions, rather than the magnitude of price differentials. Applying this framework to maize price transmission between South Africa and Zambia shows no transmission during periods of high imports, when the government was heavily involved in maize importation, but stronger transmission during periods of low imports when the government was not importing. [ABSTRACT FROM AUTHOR]

Xenia is the immediate effect of pollen on seed development after pollination. This study was conducted to investigate xenia's effects on Fe and Zn concentration in self- and open-pollinated maize seeds. Eighteen maize hybrids derived from parents with varying concentrations of Fe and Zn were planted at Potchefstroom, Cedara and Vaalharts in South Africa for two seasons, 2017 and 2018. Open- and self-pollinated seeds were compared. Self-pollination of five selected healthy maize hybrids of uniform height from each plot was performed. Fe, Zn and phytic acid (Pa) analysis was conducted on self -and open-pollinated maize seeds, and the molar ratios of Fe and Zn to Pa were also calculated to assess the bioavailability of Fe and Zn. The ranges of Fe, Zn and Pa, and the molar ratios of Fe and Zn to Pa in self-pollinated maize seeds were 15.93–21.36 mg kg−1, 18.50–24.34 mg kg−1, 4.63–5.84 mg g−1, 21.97–31.22 and 23.53–30.16 under high N, and 12.76–19.29 mg kg−1, 16.78–23.50 mg kg−1, 5.05–6.48 mg g−1, 26.12–44.54 and 25.44–35.94 under low N conditions, respectively. The ranges of Fe, Zn and Pa, and the molar ratios of Fe and Zn to Pa in open-pollinated seeds were 14.34–19.12 mg kg−1, 17.27–23.27 mg kg−1, 4.96–5.89 mg g−1, 20.90–28.22 and 22.92–29.37 under high N, and 12.54–18.39 mg kg−1, 16.94–20.93 mg kg−1, 5.30–6.17 mg g−1, 27.90–38.75 and 27.95–36.34 under low N conditions, respectively. The bioavailability of Fe and Zn was high in self-pollinated seeds under high N conditions, while Fe was higher in self-pollinated seeds, and Zn was higher in open-pollinated seeds under low N conditions. Combined over seasons, there were no significant differences between the values of Fe and Zn in self- and open-pollinated seeds under both high N and low N conditions. This indicated that unknown males had no influence on Fe and Zn concentration in maize. Therefore, either self- or open-pollinated seeds can be used for Fe and Zn determination in maize crosses. [ABSTRACT FROM AUTHOR]

The presence of mycotoxins in cereal grain is a very important food safety issue with the occurrence of masked mycotoxins extensively investigated in recent years. This study investigated the variation of different Fusarium metabolites (including the related regulated, masked, and emerging mycotoxin) in maize from various agriculture regions of South Africa. The relationship between the maize producing regions, the maize type, as well as the mycotoxins was established. A total of 123 maize samples was analyzed by a LC-MS/MS multi-mycotoxin method. The results revealed that all maize types exhibited a mixture of free, masked, and emerging mycotoxins contamination across the regions with an average of 5 and up to 24 out of 42 investigated Fusarium mycotoxins, including 1 to 3 masked forms at the same time. Data obtained show that fumonisin B1, B2, B3, B4, and A1 were the most prevalent mycotoxins and had maximum contamination levels of 8908, 3383, 990, 1014, and 51.5 µg/kg, respectively. Deoxynivalenol occurred in 50% of the samples with a mean concentration of 152 µg/kg (max 1380 µg/kg). Thirty-three percent of the samples were contaminated with zearalenone at a mean concentration of 13.6 µg/kg (max 146 µg/kg). Of the masked mycotoxins, DON-3-glucoside occurred at a high incidence level of 53%. Among emerging toxins, moniliformin, fusarinolic acid, and beauvericin showed high occurrences at 98%, 98%, and 83%, and had maximum contamination levels of 1130, 3422, and 142 µg/kg, respectively. Significant differences in the contamination pattern were observed between the agricultural regions and maize types. [ABSTRACT FROM AUTHOR]