The prevalence of extreme drought and flooding is posing a threat to the food security of Sub-Saharan African countries. There are national and international calls for actions to investigate the level of resilience of existing crop cultivars to multiple abiotic stress conditions. A two-year study was carried out in South Africa to determine growth, development, yield, yield components, and physiological responses of two contrasting maize cultivars—PAN 413 (drought tolerant) and PAN 6Q-245 (drought intolerant) under drought and flooding. The drought effect on grain yield was more pronounced from mid-vegetative to tasselling stages, regardless of the cultivar with yields deviating from the control by 53–58% (2015/2016) and 34–42% (2016/2017). The effect of flooding on grain yield was pronounced at the early vegetative stage for both cultivars, with yield reductions ranging between 26–30% (2015/2016) and 15–21% (2016/2017). Results from the study indicated that existing maize cultivars (drought tolerant and drought intolerant) are both prone to likely extreme drought events experienced during the tasselling stage. Results also showed that both cultivars are prone to probable flooding events before the tasselling stage. It is recommended that plant breeders’ efforts be directed to developing maize cultivars with multiple stress tolerances.

Ecosystems in semi-arid and arid Southern Africa experience high temperatures which translate to extremely hot soil surface temperatures. High soil surface temperatures lead to a decrease in seed germination and consequently less plant cover in these areas. To facilitate maintenance of optimum plant cover, soil surface temperature should be moderated with appropriate mitigation techniques. Temperature variations in low (kg.0.5 m⁻³) and high density (1 kg m⁻³) brush packing treatments were compared to bare soil. We also measured the grass productivity (g.m⁻²) against the effect of temperature in the three treatments. iButtons® were used to log soil surface temperature every hour for seven months. Daily and nightly temperatures of the hottest months were compared amongst the three treatments. Mid-day temperatures, corresponding to peak heat stress were also compared between the three treatments. There was a significant difference (p < 0.01) in soil surface temperature between the three treatments. The high density treatment was the most buffered against temperature variation, when compared to the bare soil. Grass production was generally higher in the high density treatment. Productivity can be increased by mulching the soil with brush packing as this will improve soil surface conditions such as moderating abrupt changes in temperatures to assist plant growth.

South African soils generally lack native Bradyrhizobium strains that nodulate and fix atmospheric nitrogen (N₂) in soybeans (Glycine max L.). It is therefore very important to inoculate soybeans with products that contain effective Bradyrhizobium strains as active ingredients. In this study, a field experiment was conducted on two bioclimatic zones in South Africa during the 2019/2020 season to assess the effect of Bradyrhizobium japonicum strain WB74 inoculant formulation on nitrogen fixation, growth and yield improvement in soybeans. The first bioclimatic zone was characterized by a sandy clay loam soil, whereas the second bioclimatic zone has a sandy loam soil. The results showed that inoculation of soybeans with both peat and liquid formulations of Bradyrhizobium japonicum WB74 increased nitrogen uptake, which resulted in yield increase. The amount of N fixed was measured as ¹⁵N isotopes and increased with all treatments compared to the uninoculated control in both liquid and peat inoculant formulations. In bioclimatic zone A, slightly better results were obtained using the liquid formulation (1.79 t ha⁻¹ for liquid compared to 1.75 t ha⁻¹ for peat treatments), while peat formulations performed better in bioclimatic zone B (1.75 t ha⁻¹ for peat compared to 1.71 t ha⁻¹ for liquid treatments). In both areas higher yields were obtained with the formulations used in this study compared to the registered standards (treatment T3). The findings in this study provide vital information in the development and application of formulated microbial inoculants for sustainable agriculture in South Africa.

South Africa’s climate studies generally focus on coarser provincial levels, which aid policy recommendations, but have limited application at the farm level. District level climate studies are essential for farmer participation in climate change mitigation strategies and management. Our study aimed to investigate historical climate data for trends and their influence on maize yields at the magisterial level. Six sites were selected from three major maize-producing provinces in South Africa: Mpumalanga, Northwest, and Free State. Magisterial districts in each province were selected from different Köppen-Geiger climate zones. The climate variables assessed by the Mann–Kendall trend test included maximum or minimum temperature, rainfall, number of extreme high-temperature days, rainfall onset and cessation from 1986 to 2016. The average maximum temperatures were observed to have significant upward trends in most locations, except for Schweizer-Reneke and Bethlehem. The fastest rate of change was observed at Klerksdorp (0.1 °C per 30 years of study), while the Schweizer-Reneke district was the slowest (0.05 °C per 30 years of study). No significant changes were observed in rainfall onset, cessation, or total rainfall in Schweizer-Reneke, Standerton, and Bethlehem, which are scattered across the different provinces. The other districts in each province showed significant changes in these parameters. Rainfall accounted for the significant variation in maize yields over the study period, explaining between 18 and 40% of the variation in the North West, and between 1 and 17% in the Free State. These findings highlight the importance of understanding location-specific changes at a finer scale, which can help farming communities adjust agronomic practices and adapt to local climate shifts.

A field experiment was conducted from November to March during the 2012 / 2013 planting season at Africa University farm, Mutare, Zimbabwe to evaluate the effects of plant spacing and different potato varieties on growth, yield and quality of potato (Solanum tuberosum L.). The experiment was designed as a randomized complete block design with 4 × 3 factorial arrangements of treatments. The first factor was plant spacing (in-row spacing); 20, 25, 30 and 35 cm. The second factor was varieties: BP1, KY20 and Mnandi. Very close spacing produced a high number of small sized tubers leading to reduced marketable yield. The highest stem count was observed at high plant densities, the lowest at low plant densities. At low density plantings, leaf number per plant was high and at high density plantings the leaf number was reduced across all varieties. BP1 and KY20 exhibited the highest specific gravity and Mnandi had the least. Results of the study suggest that a wider spacing of 90 by 35 cm can be advantageous for all the three varieties since all the varieties compensated for the additional spacing to produce the highest marketable yield yet with less seed thus reducing production cost. Also from the study, an in-row spacing of 25 cm can be used by seed producers since the highest number of medium sized tubers was obtained and this size is normally used as seed. Key words: Plant spacing, potato yield, potato quality, potato varieties.