Globally, lightning causes significant injury, death, and damage to infrastructure annually. In comparison to the rest of the world, South Africa has one of the highest incidences of lightning-related injuries and deaths. The latest available lightning detection techniques and technologies are reviewed and include current research in South Africa and South Africa's lightning detection challenges. Technological advances have contributed towards improving lightning detection and monitoring activities in many countries. South Africa has made considerably more progress in the field of lightning research than other African countries and possesses one of the three ground-based lightning detection networks in the southern hemisphere. However, despite these developments, rural communities in South Africa, and indeed in Africa, remain vulnerable to lightning, the occurrence of which is predicted to increase with climate change. A large proportion of the population of African countries resides in rural areas, where citizens participate in subsistence farming, and built infrastructure is not lightning safe. We recommend a call for the integration of indigenous and scientific knowledge as well as for the development of a participatory early warning system. Investigations into determining the most effective way to utilise existing monitoring networks - but with warning dissemination to rural communities - are also required. Lastly, future research on the development of lightning-safe rural dwellings or shelters, especially in lightning prone areas, is needed.SIGNIFICANCE: • Climate change projections of increases in lightning incidence highlight an increased risk for vulnerable communities. • There is a lack of literature focusing on lightning detection within rural communities. • Technological advances now allow for better dissemination of lightning information and early warning within rural communities. • The South African Lightning Detection Network is operational at a national level; however, there is no dissemination at a local level. • There are currently no recommended design guidelines for informal dwellings and no safety protocols for rural communities.

There is a need to mainstream traditional crops in sub-Saharan Africa, in order to tackle food and nutritional insecurity through incorporating nutritional quality into crop water productivity, in the wider context of the water-food-nutrition-health nexus. The objective of the study was to determine the effect of irrigation water regimes on the nutritional yield (NY) and nutritional water productivity (NWP) of cowpea under Moistube irrigation (MTI) and subsurface drip irrigation (SDI). We hypothesized that NY and NWP of cowpea were not different under MTI and SDI and that deficit irrigation improved NWP. The experiment was laid as a split-plot design arranged in randomized complete blocks, replicated 3 times, with 3 irrigation water regimes: 100% of crop evapotranspiration (ETc), 70% of ETc, and 40% of ETc. Irrigation type and water regime did not significantly (p > 0.05) affect the nutritional quality of cowpea. Similarly, NWP of crude fat (28.20-39.20 g∙m-3), ash (47.20-50.70 g∙m-3) and crude fibre (30.70-48.10 g∙m-3) did not vary significantly. However, protein and carbohydrate NWP showed significant (p < 0.05) differences across irrigation water regimes and irrigation type. The highest protein NWP (276.20 g∙m-3) was attained under MTI at 100% ETc, which was significantly (p < 0.05) higher than SDI (237.1 g∙m-3) and MTI (189.8 g∙m-3) at 40% ETc. Cowpea is suited for production in water-scarce environments; however, there are trade-offs with carbohydrate NWP. This should not be of concern as often diets are already energy-dense but lacking in other micronutrients.

Moistube irrigation (MTI) is a new subsurface irrigation technology where the water emits from a semipermeable membrane at a slow rate depending on applied pressure and soil water potential. There is lack of information on how various crops respond to MTI. This study determined growth, yield and water use efficiency (WUE) of cowpea (Vigna unguiculata (L.) Walp) under varying water regimes under MTI and subsurface drip irrigation (SDI), using field and glasshouse experiments in summer and winter of 2018, respectively. A split-plot design arranged in randomized complete blocks, replicated 3 times, with SDI as the control experiment was used. The main plot was irrigation type while the sub-plots were the water regimes. The water treatments consisted of full irrigation (100% of crop water requirement (ETc)), and deficit irrigation (DI) of 70% ETc and 40% ETc. Water deficit had a significant effect (p < 0.05) on time to flowering; plants under 40% ETc flowered 14 days earlier than plants at 100% ETc. There were significant (p < 0.05) differences in yield components. Grain yields were 1 280 kg-ha-1, 2 401 kg-ha-1 and 3 189 kg-ha-1 for 40% ETc, 70% ETc and 100% ETc, respectively, but no significant (p > 0.05) differences were recorded between SDI and MTI. However, at 40% ETc, SDI had 15% higher yield than MTI. Biomass varied significantly (p < 0.05) with irrigation type and water treatment. Grain WUE varied significantly (p < 0.05) among the water regimes. The highest WUE was achieved under SDI at 70% ETc but was not significantly different from that under MTI at 70% ETc. In conclusion, performance of cowpea was similar under the two irrigation systems under moderate DI but was better for SDI under severe DI with respect to biomass and WUE for the summer trial. Moderate DI improved the grain WUE while all the DI conditions improved the biomass WUE.

Grain legumes have potential to contribute to food and nutritional security in water-scarce areas. Information on their yield, water use and water productivity (WP) would be useful for their promotion. The aim of the study was to make a comparative assessment of adaptation, yield, water use and WP of an African indigenous grain legume (bambara groundnut) and two major grain legumes (dry bean and groundnut) under rainfed, deficit and optimum irrigation conditions. Field trials were conducted during the 2015/16 and 2016/17 summer seasons in KwaZulu-Natal, South Africa, using a split-plot design arranged in completely randomised blocks with three replications. Data collected included stomatal conductance, leaf area index, timing of key phenological stages and yield. Water use was calculated as a residual of the soil water balance. Water productivity was obtained as the quotient of grain yield and water use. Crops adapted to limited soil water availability through stomatal regulation and reduction in canopy size and duration. Yield, yield components and WP varied significantly (P < 0.05) among crop species. During 2015/16, groundnut had the highest yield and WP (10 540 kg·ha−1 and 0.99 kg·m−3, respectively). During 2016/17, the highest yield and WP were observed in dry bean, 2 911 kg·ha−1 and 0.75 kg·m−3, respectively. For both seasons, dry bean had the lowest water use (143-268 mm) across all water treatments. Dry bean and groundnut out-performed bambara groundnut with respect to yield, harvest index and WP. For any promotion of bambara groundnut as an alternative crop, there is need for crop improvement to improve yield and WP.

Predicting yield response to water is important in rainfed agriculture. The objective of this study was to calibrate and test AquaCrop for simulating yield of 3 sorghum genotypes (PAN8816, a hybrid; Macia, an open-pollinated variety; and Ujiba, a landrace) grown during the 2013/14 and 2014/15 planting seasons (early, optimal and late planting dates). Variables considered during model evaluation included canopy cover (CC), biomass (B) and yield (Y). The model was able to simulate CC (R² ≥ 0.710; root mean square error (RMSE) ≤ 22.73%; Willmott's d-index (d) ≥ 0.998), biomass accumulation (R² ≥ 0.900; RMSE ≤ 10.45%; d ≥ 0.850), harvest index (R² ≥ 0.902; RMSE ≤ 7.17%; d ≥ 0.987) and yield (R² ≥ 0.945; RMSE ≤ 3.53%; d ≥ 0.783) well for all genotypes and planting dates after calibration. AquaCrop over-estimated biomass and crop yield. The relatively good simulations produced by the minimum data input calibration confirm AquaCrop's simplicity and suitability for use in places where extensive datasets may be unavailable. Biomass and yield overestimation resulting from the use of the minimum data input calibration suggests that other parameters (water productivity, canopy sensitivity to water stress and water stress coefficient) are required to improve canopy and yield predictions for sorghum genotypes.

Sweet potato is an important 'indigenised' root crop in South Africa. It features prominently in smallholder cropping systems because of its versatility, drought tolerance and positive role in food security. It outranks most staple crops in vitamins, minerals, dietary fibre and protein content. Much information is available on sweet potato as a drought tolerant and food security crop, but critical reviews that link its drought tolerance with food security are lacking. We review sweet potato as a food security crop, focusing on mechanisms associated with drought. We conclude that the crop has great potential in the light of imminent challenges associated with drought as a negative effect of climate change.

Bambara groundnut is slow to establish and this has negative implications for total water use. Consideration of bambara groundnut as a water-efficient crop for dry areas will benefit from an understanding of water use efficiency and water use characteristics during establishment. We investigated whether there is an association between seed-coat colour of bambara groundnut seeds and water use efficiency. A secondary objective was to determine physiological and metabolic responses of bambara groundnut to terminal water stress during seedling establishment. Bambara groundnut seedlings showed reduced seedling canopy growth, increased root length and root: shoot ratio, as well as increased total soluble sugars and tissue water potential with decreasing water availability - traits associated with drought avoidance mechanisms. Consequently, seedling water use efficiency improved with decreasing water availability. Acclimation to water stress was observed under terminal stress; previously stressed seedlings responded better than previously non-stressed seedlings. Dark-coloured seeds had higher levels of phenolics which may have led to their enhanced performance during seedling emergence as well as improved drought tolerance and seedling WUE.

Understanding seed quality and water use characteristics of maize (Zea mays L.) landraces will improve food security among subsistence farmers who still cultivate them. The objective of this study was to evaluate seed quality and water use characteristics of two maize landraces (GQ1 and GQ2) compared with two commercial hybrids (SC701 and PAN53). Seed quality was determined by the standard germination, electrical conductivity, and tetrazolium tests. A controlled environment study was conducted in which the landraces were compared with hybrids across three water treatments (30% ETc; 50% ETc, and 80% ETc). Although landrace GQ2 performed at par with the hybrids, overall, seed quality tests showed that hybrids had superior seed quality than landraces. This was also confirmed by highly significant emergence results (P < 0.001) from pot trials where SC701 and PAN53 had higher emergence (100% and 94.44%, respectively) compared with GQ2 (86.11%) and GQ1 (61.11%). Subjecting landraces and hybrids to water stress (50% and 30% ETc) resulted in shorter plants with fewer leaves and earlier tasselling compared with non-stressed plants (80% ETc). Plant height for the 30% ETc water treatment was 156.1 cm compared with 175.8 cm for the 80% ETc water treatment, while plants under the 30% ETc water treatment tasseled at 105.4 d compared with 129.5 d for the 80% ETc water treatment. The GQ2 landrace continued to perform similar to, and often better, than the hybrid varieties, especially under stress conditions. Yield was poor under controlled conditions. Performance of the GQ2 landrace for both seed quality tests and under controlled conditions shows that landraces remain an important germplasm resource.

Sweet potato is an important staple, and it is mainly known for its contribution of β-carotene in human diet. The effects of cultivar and habitat on this pigment and other nutritional characteristics of the crop still require investigation. In this study, three locally bred cultivars of sweet potato, two of which are orange-fleshed, were grown in three different agro-ecological areas to determine soluble sugar content, β-carotene, and total antioxidants of roots. In addition antioxidant activity, total carotenoids, and chlorophyll content were determined in edible leaves. Reducing sugars, β-carotene, total antioxidants capacity, total carotenoids, and chlorophyll content were significantly affected by environmental conditions. The location at lower altitude and closer to the coastline showed high evapotranspiration, thus reducing sugar content, antioxidant activity, and phytonutrients in both storage roots and leaves. Absence of water stress in agro-ecological locations further inland and at higher altitudes was associated with an increase in these compounds. Free radical scavenging activity of DPPH was higher in the storage roots (610.49 µmoles TE/100g) than in the leaves (426.06 µmoles TE/100g); nevertheless, opposite results were found for the ferric ion reducing activity (FRAP). The deep orange-fleshed cultivar A45 contained high β-carotene (15 mg/100g), which is enough to meet RDA for vitamin A. There is evidence of agro-ecological effect on sweet potato nutritional value.