Agricultural production is highly sensitive to climate and weather perturbations. Maize is the main crop cultivated in South Africa and production is predominantly rain-fed. South Africa’s climate, especially rainfall, is extremely variable which influences the water available for agriculture and makes rain-fed cropping very risky. In the aim to reduce the uncertainty in the climate of the forthcoming season, this study investigates whether seasonal climate forecasts can be used to predict maize yields for South Africa with a usable level of skill. Maize yield, under rain-fed conditions, is simulated for each of the magisterial districts in the primary maize producing region of South Africa for the period from 1979 to 1999. The ability of the CERES-Maize model to simulate South African maize yields is established by forcing the CERES-Maize model with observed weather data. The simulated maize yields obtained by forcing the CERES-Maize model with observed weather data set the target skill level for the simulation systems that incorporate Global Circulation Models (GCMs). Two GCMs produced the simulated fields for this study, they are the Conformal Cubic Atmospheric Model (CCAM) and the ECHAM4.5 model. CCAM ran a 5 and ECHAM4.5 a 6- member ensemble of simulations on horizontal grids of 2.1° x 2.1° and 2.8° x 2.8° respectively. Both models were forced with observed sea-surface temperatures for the period 1979 to 2003. The CERES-Maize model is forced with each ensemble member of the CCAM-simulated fields and with each ensemble member of the ECHAM4.5-simulated fields. The CERES-CCAM simulated maize yields and CERES-ECHAM4.5 simulated maize yields are combined to form a Multi-Model maize yield ensemble system. The simulated yields are verified against actual maize yields. The CERES-Maize model shows significant skill in simulating South Africa maize yields. CERES-Maize model simulations using the CCAM-simulated fields produced skill levels comparable to the target skill, while the CERES-ECHAM4.5 simulation system illustrated poor skill. The Multi-Model system presented here could therefore not outscore the skill of the best single-model simulation system (CERES-CCAM). Notwithstanding, the CERES-Maize model has the potential to be used in an operational environment to predict South African maize yields, provided that the GCM forecast fields used to force the model are adequately skilful. Such a yield prediction system does not currently exist in South Africa. / Dissertation (MSc)--University of Pretoria, 2009. / Geography, Geoinformatics and Meteorology / Unrestricted

The study attempted to analyse the impacts of the ‘fast track’ land reform on maize production in Zimbabwe. This purpose was tackled by constructing a partial equilibrium model that depicted what could have happened if no further policy shifts had taken place after 2001. Setting up a partial equilibrium model required a sound understanding of the functioning of the Zimbabwe’s maize market. The institutional structure of the Zimbabwean maize market was explored to inform the model development process that would allow for the development of the baseline model. Developing the model started off with the estimation of single equations which were collapsed into a simultaneous system of equations through the use of a combination of ordinary least squares and generalised least squares techniques. The development of the simulation model required that assumptions be made for exogenous variables, and crafted assumptions were based on the 2000 macro-economic and institutional environment as well as agricultural policies. The re-simulated baseline model that was constructed in this study was used to make projections based on the various trends of exogenous variables in 2000. This means that the model generated an artificial data set based on what the maize market would have looked like under a set of the pre-2000 existent policy conditions. As such, all the shifts in the political and economic environment that took place after 2000 were not introduced in the model. The ‘fast track’ land reform policy was thus assessed based on the performance of the baseline model using a range of “what if” assumptions. Therefore, the re-simulated baseline solutions discussed result not only from policy shifts that occurred before 2000, but also from the convergence of hypothetical political and economic stability within the period in question. The results of the re-simulated baseline indicated that the commercial area harvested was negatively affected by the expropriation of commercial farms. The arguments in literature that the ‘fast track’ land reform policy shift contributed the loss in area planted owing to the stalling of farming operations due to political unrest, economic instability and input shortages were supported by the model results which showed that total area harvested would have been higher under pre-2000 conditions. From the re-simulated baseline results, the difference between actual and would be outcomes revealed that the total maize production was 13.27% less than what could have been produced in 2001, the year that the ‘fast track’ land reform policy was formally implemented. In view of the 2002/03 drought, output was 57.44% less and 33.53% less than what could have actually been produced for the 2002 and 2003 seasons respectively. In the 2005 drought season, the total maize production was 41.8% less than what could have been produced without the ‘fast track’ land reform. This may imply that droughts would have been less severe if the ‘fast track’ land reform was not implemented. In 2007, the baseline showed that the nation could have produced almost 48.03% more than what was actually produced. Therefore, according to the model results, the assertion that the ‘fast track’ land reform contributed, to a fair extent, to the underperformance of the maize sector still holds. The model developed in this dissertation contributes to an understanding of not only the general structure of the maize market, but also of the impact of the ‘fast track’ land reform policy on the Zimbabwean maize market based on how the market itself could have performed under the absence of these land reforms. The baseline model revealed that the maize sector performed below potential within the period of the ‘fast track’ land reform. The maize market model could thus be used as a tool that may assist policymakers to design future strategies that will help enhance maize sector performance. / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Agricultural Economics, Extension and Rural Development / unrestricted

Maize is the most important cereal crop grown in areas of South Africa by both small-scale and commercial farmers. Maize monocropping without sufficient input and declining soil nitrogen content are some of the factors that limit yield. The objective of the study was to evaluate the effect of different cowpea cultivars and populations on growth, yield and yield components of succeeding maize. The effects of cropping systems on soil N content were also observed. Field experiments were conducted during the 2005/2006 and 2006/2007 growing seasons at Potchefstroom and Taung in North West province. The trial consisted of four cowpea cultivars: PAN 311 (short duration cowpea cultivar), CH 84, Bechuana white (medium duration cowpea cultivar) and TVU 1124 (long duration cowpea cultivar) and, four planting densities (10 000, 15 000, 20 000 and 40 000 plants ha-1). Maize was used as sequential test crop to determine the residual effect of previous cowpea treatments. Cowpea grain yield increased as planting density increased at both localities. TVU 1124 gave highest grain yield of all cowpea cultivars at both localities. Total dry matter yield also increased with increasing planting density. After cowpea soil NO3- and NH4+ content increased with increasing density. Similarly, soil NO3- content of maize following cowpea showed a considerable improvement, compared to maize monocropping. The highest soil NO3- and NH4+ content was observed when maize followed Bechuana White. Significant differences were also observed in soil microbial activities among the cultivars. Maize grain yields and plant height responded positively to the previous cowpea crop, compared with maize monocropping at both locations, but especially at Taung. Maize stover yield, cob length and KNC significantly responded to maize and cowpea rotation compared to maize monocropping at Taung. These results further confirm the potential of using cowpea to contribute soil N to subsequent maize crops in a rotational system. Copyright / Dissertation (MScAgric)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

This study examines history, climate, and distribution in relation to the chemical content of yellow dent corn.

Maize production remains low in Eswatini. The small country is still unable to meet the local demand through local production. Maize is Eswatini’s staple food but the country has not yet reached self-sufficiency. This deficiency or shortfall in local maize production has been a persistent problem since the country’s independence. To fight this shortfall and reach self-sufficiency, the National Maize Corporation (NMC) was formed in 1985. The main purpose of the NMC is to keep the local demand satisfied. The NMC, as the only importer of white maize into Eswatini, does this by importing the deficit demand from South Africa. Stability of the local white maize price is also one of the responsibilities of the NMC. This study’s overarching aim was to determine whether or not a significant relationship exists between the maize prices as quoted on SAFEX and the local maize price in Eswatini. This is done to see if the importer of maize in Eswatini, the NMC, can hedge the price risk on SAFEX. The study also maps the Eswatini imported and local maize value-chain through the current price discovery mechanism. Secondary data offered by the NMC and data from the Ministry of Agriculture in Eswatini and educational journals were used in the study. Econometric time series methods were used along with monthly data from 2008 to 2019. Two hypotheses were tested during the study. The first hypothesis tested for the existence of a significant relationship between maize prices as quoted on SAFEX and the local maize price in Eswatini. The second hypothesis follows the first, determining whether or not hedging on SAFEX could be used as a tool to minimise price risk on the domestic price market in Eswatini. The study confirms that a long-run relationship exists between the South African maize market and the Eswatini maize market. The study showed that a 1% increase in the South African price led to a 0.67% increase in the local Eswatini prices. This indicates a slow rate shift in prices. Short-run dynamics indicated a 12.5% adjustment to equilibrium per term, which is a slow adjustment as a result of market conditions in Eswatini. The study also revealed asymmetry in price transmission and that the Eswatini prices only respond to positive changes (price increase) in the South African prices. This reveals that the two markets are poorly integrated. Due to the significant relationship between the two markets, it can be acknowledged that SAFEX could be used to hedge price risk by Eswatini through the NMC. Through mapping down the maize value-chain, the study discovered that the Eswatini maize market is not a liberalised one and value addition to maize through the chain is minimal. The relationship between the two maize markets, as well as the maize market of Eswatini, could still improve if means to liberate the market were to be exercised by the NMC and local government. This study can serve as the basis for understanding how risk management tools could be used by the Eswatini maize market and how the market could be improved or liberalised. / Dissertation (MSc Agric (Agricultural Economics))--University of Pretoria, 2021. / African Research Consortium (AERC) / Collaborative Master of Science Programme in Agricultural and Applied Economics (CMAAE) / Bill and Melinda Gates Foundation / Agricultural Economics, Extension and Rural Development / MSc Agric (Agricultural Economics) / Unrestricted

The southern region of Mozambique is characterized by arid to semi-arid climatic conditions with soils of poor fertility and low water retention capacity. The rainfall season is from September to April. In some areas, the rain season accommodates two production cycles, which is augmented by extended or unexpected rains in May and June. Maize is the main crop in this region. The major limiting factors for maize production in the Chókwè District under rainfed agriculture are rainfall amount and its distribution and soil fertility. Water productivity in this region is very low. The Challenge Program on Water and Food (CPWF), for which the slogan was “more crop per drop”, has attempted to identify and address water productivity constraints throughout the Limpopo River Basin (LRB). This study considers the water productivity in dryland areas, assuming that yields may not be only limited by water, but also by soil fertility. The study was aimed at investigating the improvement of water productivity by correcting nutrient deficiencies and recommending strategies to mitigate these deficiencies. A field experiment was conducted at Chókwè Agrarian Research Centre with maize cultivar (cv. Matuba). Matuba was selected because of its high tolerance to drought. Treatments were based on the most limiting soil nutrients at the experimental site. Crop parameters measured included total dry matter, fractional interception of photosynthetically active radiation (FIPAR), leaf area and grain yield. In addition, the Soil Water Balance (SWB) model was used to simulate potential yields with no nutrient limitations. Results of this study illustrated that the application of N resulted in improvements in total dry matter yield, leaf area index (LAI), FIPAR and water use efficiency (WUE). Application of both N and P improved the grain yield, leaf area duration (LAD) and WUE. SWB model simulations indicate that in only 1 out of 5 years in Chókwè District, the simulated yields were not higher compared to actual yields (0.2 - 1 ton ha-1). In conclusion, grain yield improvements are expected if nutrition is kept at optimum levels. This implies that in most years dryland yields are in fact nutrient limited and better nutrition can be used as a strategy to improve water productivity (WP) and grain yield / Dissertation (MSc Agric)--University of Pretoria, 2011. / gm2014 / Plant Production and Soil Science / unrestricted

Maize is the most grown staple crop in Africa, and white maize is of particular importance because it is the dominant staple food particularly throughout southern Africa to the extent that maize shortages lead to food security emergencies. These emergencies are compounded by SADC’s limited ability to respond to production and supply shocks. In response to these shocks, SADC countries supplement local maize production with trade and food aid leading to a robust regional white maize market. In an attempt to bolster trade SADC member states sign substantial regional arrangements, with similar objectives and common participants all in the hope of strengthening trade and with it maize trade. This study seeks to find means to improve intra-SADC maize trade relations, through defining the determinants for intra-regional maize trade, and determine if SADC members’ sub-regional groupings have an effect on maize trade. The study makes use of a gravity model to estimate the value of trade; specifically a Tobit model with random effects by Maximum Likelihood Estimation. The partner country population was found to have a positive effect (0.749) on maize trade at 5% level of significance. This suggests that countries that have greater populations and consequently larger market sizes for the regional staple maize tend to trade more. Maize aid distribution was found to be a statistically significant determinant of intra-regional maize trade to the extent that it encourages regional maize trade. Transport infrastructure was also found to positively influence intra-SADC maize trade, as infrastructure transportation systems are critical for the purposes of moving goods and labour to facilitate production and trade. The premise that bilateral maize trade between any two countries is negatively related to the relative importance of economic relationships between the reporter country and the partner countries that are located far away, as opposed to those located nearby, is supported by the negative impact distance has on maize trade (-1.670 significant at 10% level), while the propensity to trade increases if the two trading countries share a common border. The net grain position of member states influences intra-SADC maize trade as shown by the statistically significant positive relationship between trade and a net grain deficit position, suggesting that SADC member states are likely to engage in intra-SADC trade should they find themselves in a deficit trade position presumably from the nearest most accessible surplus state. Sub-regional groups SACU and COMESA were found to have no influence on maize trade. / Dissertation (MSc(Agric))--University of Pretoria, 2013. / Agricultural Economics, Extension and Rural Development / unrestricted

In Swaziland, maize is important for food security, yet its production is low and the country has not achieved self-sufficiency. Swaziland has had a shortfall in domestic maize production since independence. About 80 percent of the rural population never has enough maize for consumption. The National Maize Corporation (NMC) was established as a self-sufficiency mechanism in 1985. The NMC is the only white maize importer and is also responsible for the stabilisation of domestic prices. The organisation has endeavoured to stabilise Swaziland's maize prices, though they are still high by regional comparisons. This study seeks to investigate the relationship between Swaziland and South African white maize prices in the presence of maize marketing and pricing policy, as implemented by the NMC. The maize marketing policy controls flow of maize imports and exports in Swaziland, while the pricing policy controls the domestic white maize prices. The current pricing relationship between the two countries was compared with a scenario where marketing and pricing policies in Swaziland are absent. This was done in order to gauge the effect that these policies have on the integration of Swaziland into the regional maize market and ultimately how Swaziland maize prices are affected by price transmission process in the presence and absence of these policies. The study used secondary data from the NMC, the Ministry of Agriculture, and journals. Monthly data from 2000 to 2014 are used and econometric time series techniques are applied. The study hypothesised that there is a long-run relationship between Swaziland and South African maize prices, given the current market structure. It also hypothesised the short-run dynamics correct deviations from the long run in a fast and efficient manner. Lastly, it is hypothesised that current policies are not hampering marketing integration or impeding regional price signals to flow through to Swaziland maize markets. The results confirm the presence of a long-run price relationship between the above-mentioned markets. In the presence of the current maize marketing and pricing policy, the error correction term corrected or adjusted the disequilibrium, from long-run equilibrium levels, at a speed of 3.8 per cent per period, indicating relatively slow correction. This could serve as evidence of inefficient integration between the two markets and an indication of weak arbitrage process. Weak arbitrage, in turn, has definite welfare implications in that it leads to inefficient allocation of resources. In comparison to the other scenario, there is a slight difference: when analysing the relationship between import parity and Swaziland domestic prices without policy measures, short-run and long-run relationship between markets are also confirmed. Here the error correction term, however corrected the disequilibrium of the system at a speed of 4.7 percent per period. This shows a slight improvement of efficiency when policies are eliminated. This study could be useful to policy makers in that it imparts knowledge on how world price signals are transmitted to their domestic markets. Understanding the price dynamics could, therefore, facilitate policy formulation related to price and marketing in the white maize industry. The findings of this study could ultimately also inform the self-sufficiency versus food affordability debate. / Dissertation (MSc (Agric))--University of Pretoria, 2016. / Agricultural Economics, Extension and Rural Development / MSc (Agric) / Unrestricted

<p>Starter fertilizer applied with or near the seed at planting often enhances early season maize growth (<i>Zea mays</i> L.) but does not always result in higher grain yield. Other responses to starter fertilizer, such as reduced thermal time to reach silking, which suggests accelerated plant development, have been documented. The objective of this study was to examine the relationship between dry matter production and accelerated plant development with respect to 5x5 cm starter (ST) and in-furrow popup (PU) fertilizer. A field experiment was conducted in 2016 with three at-planting treatments consisting of one single rate and formulation of ST (53 N and 21 P kg ha^-1) or PU (4 N and 6 P kg ha^-1), and an untreated control. In 2018, the study included four additional site-years with treatments consisting of an intermediate (ST) or high (STH) starter fertilizer rate, and an untreated control. For ST treatments, depending on location, nitrogen (N) and phosphorus (P) fertilizer rates ranged between 26-28 and 6-10 kg ha^-1, respectively, and for STH treatments N and P fertilizer rates ranged between 47-56 and 12-20 kg ha^-1, respectively. In 2016, as new leaf collars appeared, dry matter increased exponentially, but at an equal number of leaf collars ST and PU had similar dry matter as the control. In 2018, dry matter for ST, STH, and control was also similar when normalized for leaf collar number at each site. Overall, these results suggest that enhanced dry matter at a given point in time from ST, STH, or PU was a function of accelerated leaf development as opposed to physically more robust plants of the same leaf collar number. Grain yield was unaffected by ST, STH, or PU treatments at any site-year.</p> <p>Methods used to study roots in crop fields have included extracting soil cores, excavating entire root systems, using radioactive and non-radioactive chemical tracers, or using mini-rhizotrons. However, due to the intensive nature, level of difficulty, and cost associated with these methods, their use in crop fields has been minimal. We developed an alternative method to quantify maize rooting density over time. The method involved perforated cylinders installed vertically into the soil at different distances from the row, which made roots growing into the cylinder voids visible from the soil surface and possible to count [root number density (RND)] at different depths using a video recording device (1m-long borescope). The objective of this study was to determine if the cylinder method could quantify rooting density throughout the growing season (V3, ~V7, and R2-R3) similar to the more intensive soil core method, compared in two starter fertilizer trials [continuous maize (M/M) and maize/soybean (M/S) rotation]. Cylinders were constructed with perforated (49% voids) polypropylene resin to an inside diameter of 2.58 cm and a length of 30 cm. Cylinders were painted with red and green alternating markings (5 cm) on the outside and inside walls to visually aid in identifying depth from the soil surface. After plants emerged, cylinders were inserted vertically into the soil after drilling a 3.5 cm diameter borehole. Ten perforated cylinders were installed in a parallel line 13 or 25 cm away from, and on both sides of, the planted row. Soil cores were also collected at the same relative locations for conducting root extractions and subsequent calculation of length density (RLD). At V3, methods frequently resulted in the same significant (<i>p≤</i>0.10) or insignificant (<i>p></i>0.10) main and interaction effects in both fields, whereas at ~V7 and R2-R3, there were several instances where the cylinder method failed to detect the same effects as the soil core method. At times both the cylinder method and the soil core method detected significant main or interaction effects, but the direction of the effect was opposite.</p> <p>In-furrow biological (BIO) and plant growth regulator (PGR) products, otherwise known as biostimulants, are becoming increasingly available in the commercial maize market. The objective of this study was to compare the effects of several commercially available in-furrow biostimulant products on maize growth and development, nutrient uptake, and grain yield to starter fertilizer in large-plot field trials. The study was conducted across five locations in 2016, and three locations each in 2017 and 2018 at Purdue University research farms. At each location, treatments consisted of four different BIO or PGR products plus starter fertilizer, starter fertilizer only, and an untreated control. Compared to the control, starter-only increased grain yield at 7 of 8 site-years in 2016 and 2018 ranging from 125 to 753 kg ha^-1, depending on location, but no increase was found at any of the 3 locations in 2017. Grain yield was increased (3 of 11 site-years) or decreased (2 of 11 site-years) by some of the BIO or PGR products, but in 6 of 11 site-years none of the products affected yield compared to starter-only.</p>

Apoplastic barriers (exodermis and endodermis) control free movement of substances by apoplast, which is achieved by specific cell wall modifications. Differentiation of these barriers is to some extent variable. It has been demonstrated many times that the differentiation of root apoplastic barriers is strongly influenced by unfavourable environmental conditions. Many stress factors accelerate the deposition of apoplastic barriers. This work deals with the relationship between availability of nutrients and development of root barriers and mechanisms of coordination of developmental processes in roots, including the involvement of auxin and other phytohormones in the coordination of these processes. The exodermis developmental plasticity is followed in maize (Zea mays L.) under conditions of various nutrient deficiencies. The most important results are presented by anatomical analysis, which shows a significant acceleration of exodermis and endodermis differentiation in the N and P deficiency on the contrary, the slowing of differentiation in the absence of Fe and K. This effect is apparently a result of systemic rather than local root system responses because it was not observed with localized deficiency. This thesis also test the influence of some phytohormones on the development of apoplastic...