Stomatal behavior of cowpea genotypes grown under varying moisture levels

Drought is a major limitation to crop productivity worldwide. Plants lose most of their water through stomata, thus making stomata an important organ in the control of transpiration and photosynthesis. This study assessed the stomatal behavior of four cowpea genotypes grown under four moisture levels under hot semi-arid conditions. Stomatal conductance (gs) was measured at 47, 54, 70 and 77 days after planting (DAP). Biomass and carbon isotope composition (C-13) were also determined at flowering. Genotype and moisture level significantly influenced gs. Genotypes varied in gs at vegetative stages (47 and 54 DAP) only. TVu4607 had higher gs under severe drought conditions at both 47 and 54 DAP. On the other hand, moisture level influenced gs at 54 and 70 DAP only. Stomatal conductance was severely restricted in cowpea under both moderate and severe drought conditions as gs was mostly below the threshold 0.10 mol m(-2) s(-1). Relationships between: biomass and gs, and C-13 and gs were positive under severe drought only. The findings revealed that cowpea genotypes vary in gs under dry conditions and that the variation is more prominent at vegetative stage, suggesting that cowpea productivity in dry areas could be improved through selection of genotypes that maintain higher gs under dry conditions

Agroforestry Trees for Fodder Production in Limpopo Province, South Africa

Climate change and land degradation, resulting from human-induced pressures on ecosystems are threatening crop productivity, food and feed supply, and food security in the Limpopo Province of South Africa, especially within the socio-economically marginalised communities. A combination of survey and field experimentations were conducted from 2016 to 2018 to assess potential climate-smart farming practices that can assist farmers to adapt to local climate change and variability in the province. Results from the survey revealed that agroforestry system with woody perennial speices which encourages minimum soil disturbance, increase soil cover and increase agrobiodiversity is being promoted in the province as one of the effective avenues to achieve sustainability in farming systems in the midst of global climate change. Moringa oleifera and Acacia karroo (now Vachellia karroo) were identified as potential agroforestry tree species to address feed gaps during dry winter months, based on their good nutritional value, drought hardiness and effective carbon capture for climate change mitigation

Seasonal effect on Moringa oleifera gaseous exchange and water use efficiency under diverse planting densities

The study on Moringa oleifera was conducted over twelve months during 2014-2015 to evaluate the impact of the growing season and varying planting densities on biomass yield and physiological at-tributes under dryland conditions. Trial was established at densities of 5000, 2500, 1667 and 1250 plants ha-1, with eight replicates. The increase in planting density led to an increase in biomass production. The monthly and seasonal data collected showed significant differences in net photosynthetic rate, transpiration, sub-stomatal CO2 and stomatal conductance. However, planting densities of M. oleifera had no significant effect on all the gaseous exchange parameters measured. The results further revealed that the amount of carbon dioxide assimilated by the tree is not attributable to photosynthetic and transpiration rates as well as stomatal conductance. Under water shortage condition and high temperature, M. oleifera used an adaptation strategy by reducing stomatal conductance and transpiration and hence increasing water use efficiency. Moringa oleifera thus has the ability to sequester carbon even under water stress conditions. The tree can therefore be recommended for planting at a relatively high density of 5000 plants ha-1 in many parts of Limpopo province where temperatures are favorable for improved farmers’ livelihoods as well as for climate change mitigation

Modeling the multi-functionality of African savanna landscapes under global change

Various recent publications have indicated that accelerated global change and its negative impacts on terrestrial ecosystems in Southern Africa urgently demand quantitative assessment and modelling of a range of ecosystem services on which rural communities depend. Information is needed on how these Ecosystem Services (ES) can be enhanced through sustainable land management interventions and enabling policies. Yet, it has also been claimed that, to date, the required system analyses, data and tools to quantify important interactions between biophysical and socio-economic components, their resilience and ability to contribute to livelihood needs do not exist. We disagree, but acknowledge that building an appropriate integrative modelling framework for assessing the multi-functionality of savanna landscapes is challenging. Yet, in this Letter-to-the-Editor, we show that a number of suitable modelling components and required data already exist and can be mobilized and integrated with emerging data and tools to provide answers to problem-driven questions posed by stakeholders on land management and policy issues.German Federal Ministry of Education and Researchhttps://onlinelibrary.wiley.com/journal/1099145xhj2022Zoology and Entomolog

The Impact of the Quality of Coal Mine Stockpile Soils on Sustainable Vegetation Growth and Productivity

Stockpiled soils are excavated from the ground during mining activities, and piled on the surface of the soil for rehabilitation purposes. These soils are often characterized by low organic matter (SOM) content, low fertility, and poor physical, chemical, and biological properties, limiting their capability for sustainable vegetation growth. The aim of the study was to evaluate the impact of stockpile soils of differing depth and quality on vegetation growth and productivity. Soils were collected at three different depths (surface, mid, and deep) as well as mixed (equal proportion of surface, mid and deep) from two stockpiles (named Stockpile 1: aged 10 and Stockpile 2: 20 years) at the coal mine near Witbank in the Mpumalanga province of South Africa. Soils were amended with different organic and inorganic fertilizer. A 2 × 4 × 5 factorial experiment in a completely randomized blocked design with four replications was established under greenhouse conditions. A grass species (Digiteria eriantha) was planted in the pots with unamended and amended soils under greenhouse conditions at 26–28 °C during the day and 16.5–18.5 °C at night. Mean values of plant height, plant cover, total fresh biomass (roots, stems and leaves), and total dry biomass were found to be higher in Stockpile 1 than in Stockpile 2 soils. Plants grown on soils with no amendments had lower mean values for major plant parameters studied. Soil amended with poultry manure and lime was found to have higher growth rate compared with soils with other soil amendments. Mixed soils had better vegetation growth than soil from other depths. Stockpiled soils in the study area cannot support vegetation growth without being amended, as evidenced by low grass growth and productivity in this study

EXTENSION SUPPORT FOR GRAIN CROP PRODUCERS UNDER CLIMATE VARIABILITY SCENARIO: IMPLICATIONS FOR EXTENSION MANAGEMENT IN LIMPOPO PROVINCE, SOUTH AFRICA

The paper examined how the farm management support provided by public extension to mitigate the eff ects of climate variability infl uences farmers’ production, and whether this support considers farmers’ capital assets. Both probability and non-probability sampling procedures were used to select districts, municipalities and farmers from 20 villages of Limpopo province, South Africa in January, 2014. Semi-structured questionnaires were used to collect data from fi eld-level extension agents and smallholder grain farmers. The most common climate variability coping strategy promoted by many agents was climate-smart agriculture practices. This strategy was applied by most users and non-users of extension support. The most popular channel used by agents to communicate information to farmers was farm visits. There were indications that agents did not consider producers’ capital assets in their choice of channels to communicate information to producers. Results further indicate that extension support, including climate variability information, contributed to increased crop yields, albeit small. It is recommended that fi eld trials be done to ensure proper application of climate variability coping measures. More use of mass media and group methods to supplement farm visits is recommended

Drought-Induced Challenges and Different Responses by Smallholder and Semicommercial Livestock Farmers in Semiarid Limpopo, South Africa—An Indicator-Based Assessment

Increased seasonal climatic variability is a major contributor to uncertainty in livestock-based livelihoods across Southern Africa. Erratic rainfall patterns and prolonged droughts have resulted in the region being identified as a climate ‘vulnerability hotspot’. Based on fieldwork conducted in the dry seasons in a semiarid region of South Africa, we present an interdisciplinary approach to assess the differential effects of drought on two types of livestock systems. Organic matter digestibility, faecal crude protein, C/N ratio and the natural abundance of faecal 15N and 13C isotopes were used as ecophysiological feed quality indicators between smallholder and semicommercial systems. These measurements were complemented with qualitative surveys. In a novel approach, we tested the potential of the isotopic signature to predict feed quality and present a significant relationship between organic matter digestibility and isotopic ratios. Indicators assessed smallholder feed quality to be significantly higher than semicommercial feed. However, animals from semicommercial farms were in significantly better condition than those from smallholding farms. Differential access to feed resources suggests that a complex feed–water–land nexus pushes smallholders into high reliance on off-farm supplements to bridge drought-induced feed deficits. The paper thus offers a contribution to intersectional work on drought effects on livestock keepers of semiarid South Africa and illustrates how ecophysiological indicators mirror socioeconomic differences

Screening cowpea genotypes for high biological nitrogen fixation and grain yield under drought conditions

Future increase in drought and heat stress will challenge legume productivity in many regions. In Sub-Saharan Africa, legumes are earmarked as an integral component in building resilience to climate change and food security in smallholder farming systems. Hence, the need for continuous screening of drought tolerant legume genotypes for sustained productivity. A 2-yr field study was conducted to identify superior cowpea genotypes with high biological nitrogen fixation (BNF), grain yield, and drought tolerance. Four genotypes, selected from a pool of 91, were grown under four moisture levels ranging from well-watered (WW) to severe water stress (SS). Grain yield, shoot biomass, nodule mass, and BNF were determined. There was significant effect of water stress on the measured parameters. Nodule mass and BNF were more sensitive to water stress compared to shoot biomass across genotypes. Water stress resulted in 80% reduction in nodule biomass between WW and SS. As a result, cowpea genotypes grown under SS conditions fixed 57% less N-2 compared to those under WW. The study also revealed significant genotypic variation in shoot biomass, grain yield, and BNF. Genotype TVu4607 was low in grain yield but performed better for BNF (71 kg N ha(-1) under WW and 30 kg N ha(-1) under SS). Genotype IT00K-1263, proved to be our superior genotype with a good balance of biomass, BNF and grain yield. Our findings suggest that future water stress may significantly affect cowpea productivity, mostly its capacity to fix nitrogen. Consequently, adaptation strategies to improve drought resistance in cowpea are needed, particularly improvement of BNF under water stress

Examining the role of institutional support in enhancing smallholder oilseed producers’ adaptability to climate change in Limpopo Province, South Africa

Smallholder oilseed production constitutes a crucial component of rural economies and continues to face the consequences of a changing climate despite the increased levels of vulnerability. This paper assesses how smallholder oilseed farmers’ adaptive capacity in Limpopo is enhanced through various institutional support schemes within the context of increased climate extremes and their need to sustain production. Six hundred farmers were interviewed across three agro-ecological zones of Limpopo Province. Results show that some of the institutions’ current operations aimed at providing support to farmers do not adequately satisfy the farmers’ needs. A strong linear relationship was observed between the number of support types received by farmers and grain yield, suggesting that farmers who received more support types were relatively less vulnerable. Educational support is ranked as the most significant contributor to enhancing farmers’ adaptive capacity. This emphasizes the need for proper linkages between farmers’ choices of adaptive methods and the types of support needed. Therefore, this study provided a diagnosis of the gaps in essential types of institutional support needed to increase farmers’ resilience, which can be used as an input to beef up the policy and positioning to improve the adaptive capacity

Yield Responses of Grain Sorghum and Cowpea in Binary and Sole Cultures under No-Tillage Conditions in Limpopo Province

Climate change is severely disrupting ecosystem services and crop productivity, resulting in lower crop growth and yields. Studies have emphasized the importance of assessing conservation practices through crop modelling to improve cropland productivity. There is a lack of accurate information in the performance of conservation practices as well as data for improved crop modelling. No-tillage sorghum–cowpea intercrop experiments were established to assess the productivity of four sorghum cultivars and cowpea at two densities of 37,037 and 74,074 per plants and generate data for improved crop modelling. The leaf area index (LAI) varied in sorghum cultivars and cowpea densities during the two growing seasons. Cultivars Enforcer and NS5511 produced the highest grain yields of 4338 kg per ha and 2120 kg per ha, respectively, at Syferkuil. Ofcolaco’s Enforcer and Avenger were the highest yielding cultivars at Ofcolaco, with mean yields of 2625 kg per ha and 1191 kg per ha, respectively. At Syferkuil, cowpea yield was 93% and 77% more in sole compared to binary cultures during the growing seasons at Syferkuil. At Ofcolaco, sole yielded approximately 96% more grain than binary. The findings confirm that for the sorghum–cowpea intercrop to improve overall system productivity, cowpea density should be increased