The key pathways for synthesizing nanoparticles are physical and chemical, usually expensive and possibly hazardous to the environment. In the recent past, the evaluation of green chemistry or biological techniques for synthesizing metal nanoparticles from plant extracts has drawn the attention of many researchers. The literature on the green production of nanoparticles using various metals (i.e., gold, silver, zinc, titanium and palladium) and plant extracts is discussed in this study. The generalized mechanism of nanoparticle synthesis involves reduction, stabilization, nucleation, aggregation and capping, followed by characterization. During biosynthesis, major difficulties often faced in maintaining the structure, size and yield of particles can be solved by monitoring the development parameters such as temperature, pH and reaction period. To establish a widely accepted approach, researchers must first explore the actual process underlying the plant-assisted synthesis of a metal nanoparticle and its action on others. The green synthesis of NPs is gaining attention owing to its facilitation of the development of alternative, sustainable, safer, less toxic and environment-friendly approaches. Thus, green nanotechnology using plant extract opens up new possibilities for the synthesis of novel nanoparticles with the desirable characteristics required for developing biosensors, biomedicine, cosmetics and nano-biotechnology, and in electrochemical, catalytic, antibacterial, electronics, sensing and other applications.

Background: One of the main causes of land degradation in South Africa is bush thickening (BT) of mainly Senegalia or Vachellia species. Restoration methods are required to control BT, and to improve grass biomass production and soil conditions in South Africa.Objectives: The objectives of this study were to determine the effect of brush packing (BP) as a restoration method to increase grass biomass production, assess soil moisture after BP on different soil types, and document the perceptions of the local communities towards BP.Method: Methods included cutting the stems of woodies with a diameter of at least 10 cm at knee height by chainsaw and manual clipping after which an arborocide was applied to the stumps. A neutron probe was used to measure volumetric moisture content at two different soil depths. The grass biomass was analysed using ANOVA at a confidence level of 95%. Quantitative and qualitative approaches were used to gather information about the perceptions of local communities towards restoration in group discussions.Results: The short-term data showed that the implementation of BP as restoration method increased grass biomass production. The soil texture influenced the volumetric soil moisture. Higher soil moisture content was found in the deeper clayey soils. The local participants’ interpretation towards the restoration project was positive.Conclusion: The project increased the grazing potential and contributed to job creation to improve the well-being of the people in the community.

Parthenium hysterophorus L. (Asteraceae), commonly known as famine weed in South Africa, is one of the most invasive weeds worldwide, accountable for losses to biodiversity, agriculture, the economy, and the health of livestock and human beings. The spread of this weed is not easy to manage or reverse. With globalization, trade, and human movement, it will continue to spread, allowing its range to expand into new areas. This weed has serious adverse effects on rangeland and agricultural crop production. Because of its unique characteristics, its invasiveness and competitive success rates are attributed to its high reproductive ability, fast growth rate, tolerance to environmental stresses, climate change adaptability, allelopathic potential, and unpalatability to animals. Parthenium hysterophorus dominates diverse habitats by spreading quickly as a contaminant of grain and other crop products and through farm machinery. It is widely distributed and has become problematic in various countries, including South Africa. It has successfully invaded several provinces in the country since its introduction in 1880. Since plant invasions are not universal, this study aimed to review research that has been conducted on the aggressive weed P. hysterophorus to understand the ecological characteristics that enable its successful establishment, the economic costs associated with its detrimental impacts, and to briefly assess knowledge gaps to improve its management strategies.

Invasive alien plants are one of the major threats to ecosystems. Many invasive plant species, such as Prosopis species, have been introduced around the world and can alter the soil properties of invaded ecosystems. It is one of the most aggressive invasive plant invaders in the North-West Province of South Africa, but little information is available about their influence on soil properties. This study was conducted to investigate the effect of Prosopis velutina invasion on selected soil properties at five different sites along the riverine system of the Molopo River in North West Province. At each study site, soil characteristics were measured from soil samples taken under P. velutina canopies, between canopies and in the benchmark stands free of Prosopis species. The effect on selected soil properties of P. velutina invasion varied between the three stands and between sites. In all the sites, almost all soils collected from under the canopies had a significantly higher soil exchangeable Ca, K, Mg, and Na, organic matter (OM), total nitrogen (TN), available phosphorus (P), Electrical conductivity (EC), and cation exchange capacity (CEC) than the other sample positions, except for the pH which had the high value in intercanopies. Significantly higher ( ) values of almost all soil properties were found on the densely invaded sites (Tshidilamolomo I and Tshidilamolomo II) compared to lightly invaded sites (Mabule, Black Heat Farm, and Bray). However, it was difficult to generalise as the effects often appear to be site-specific. In addition, the findings also indicated that soils textural classes ranged between sand, silt, and clay in all study sites with a higher proportion of sand in the benchmark than in the soil under the canopies and intercanopies. Soil characteristics differed significantly more between sites than among positions. The site effects observed in this current study provide evidences that this species may occupy a relatively broad soil niche.

Soil properties are important drivers of species distribution and community structure in grassland. This study was undertaken to assess the influence of soil properties on woody plant distribution around six selected communally managed rangelands in the District. At each communal rangeland, a total of 25 plots of 20 × 20 m were surveyed to record the density, frequency, and composition of woody species. Soil samples were collected for thirteen soil variables. A Tukey HSD (Tukey’s honestly significant difference) post hoc test was used to compare soil properties and canonical correspondence analysis (CCA) to relate the soil properties to the woody species distribution. The study recorded a total of 17 woody species in 9 families. Fabaceae was the most dominant family, and Senegalia mellifera was the most abundant and frequent encroaching species. Most of the species were native, whereas Prosopis velutina was the only invasive alien species recorded. Senegalia mellifera, P. velutina, and Terminalia sericea were considered the most encroaching in the study sites, with densities exceeding 2000 TE ha-1 (i.e., tree equivalent). CCA results exhibited the strong effect of soil variables on the distribution of woody plant species. CCA ordination analyses showed that K was the most influential soil variable on woody species distributions, followed by Mg, CEC, Na, pH, sand, clay and silt. In terms of woody distribution, the CCA diagram showed similarities between Disaneng, Logageng and Tshidilamolomo. This study provides baseline information on woody species diversity for future management of this ecosystem.

In the present study, weed plants viz., Calotropis procera, Ricinus communis, Lantana camara, Achyranthes aspera, Wedelia chinensis, and Colocasia esculenta were evaluated against Meloidogyne incognita affecting spinach. For in vitro egg masses hatching experiment, four different concentrations of aqueous extracts of weed leaves, i.e. 100%, 50%, 10%, and 1%, were analyzed. All the extracts showed varied but significant results over control (Distilled water). Furthermore, C. procera and R. communis treatment significantly inhibited J2s hatching (100% inhibition) at the 4th and 7th days of incubation in 100% concentration, while C. esculenta inhibited the least. In pot study, it was also found that the pots treated with 50 and 100 g dry leaf powder of C. procera has efficiently suppressed the root-knot disease in spinach and significantly increased growth in terms of length, fresh and dry weights, number of leaves and biochemical parameters such as chlorophyll, carotenoid content and nitrate reductase activity followed by A. aspera, L. camara, R. communis, W. chinensis while C. esculenta showed the least effect amongst the treatments. Thus, the results provide considerable data for the use of weed plants to manage the root-gall disease in spinach.