Climate change, expanding soil salinization, and the developing shortages of freshwater have negatively affected crop production around the world. Seawater and salinized lands represent potentially cultivable areas for edible salt-tolerant plants. In the present study, the effect of salinity stress on plant growth, mineral composition (macro-and micro-nutrients), and antioxidant activity in dune spinach (Tetragonia decumbens) were evaluated. The treatments consisted of three salt concentrations, 50, 100, and 200 mM, produced by adding NaCl to the nutrient solution. The control treatment had no NaCl but was sustained and irrigated by the nutrient solution. Results revealed a significant increase in total yield, branch production, and ferric reducing antioxidant power in plants irrigated with nutrient solution incorporated with 50 mM NaCl. Conversely, an increased level of salinity (200 mM) caused a decrease in chlorophyll content (SPAD), while the phenolic content, as well as nitrogen, phosphorus, and sodium, increased. The results of this study indicate that there is potential for brackish water cultivation of dune spinach for consumption, especially in provinces experiencing the adverse effect of drought and salinity, where seawater or underground saline water could be diluted and used as irrigation water in the production of this vegetable.

Leafy vegetables promote reparation of energy loss due to oxidative stress, and they have the potential to alleviate hunger and malnutrition as well as other forms of metabolic imbalance ravaging the world. However, these vegetables are underutilized, despite the fact that they harbor essential minerals needed for critical cellular activities. As amaranth is one of the earliest vegetables reputed for its high nutraceutical and therapeutic value, in this study, we explored research on the Amaranthus species, and identified areas with knowledge gaps, to harness the various biological and economic potentials of the species. Relevant published documents on the plant were retrieved from the Science Citation Index Expanded accessed through the Web of Science from 2011 to 2020; while RStudio and VOSviewer were used for data analysis and visualization, respectively. Publications over the past decade (dominated by researchers from the USA, India, and China, with a collaboration index of 3.22) showed that Amaranthus research experienced steady growth. Findings from the study revealed the importance of the research and knowledge gaps in the underutilization of the vegetable. This could be helpful in identifying prominent researchers who can be supported by government funds, to address the malnutrition problem in developing countries throughout the world.

Halophytes such as ice plants are concurrently subjected to salt and drought stresses in their natural habitats, but our knowledge about the effects of combined stress on plants is limited. In this study, the individual and combined effects of salinity and irrigation intervals on the plant growth, mineral content, and proximate and phytochemical composition of M. crystallinum were evaluated. Treatments consisted of four irrigation treatments ((1) 100 mL once a day; (2) 100 mL once every 2 days; (3) 100 mL once every 4 days; (4) 100 mL once every 8 days) with four salt concentrations (0, 200, 400, and 800 ppm) applied in each treatment. Salt concentrations were set up by adding increasing concentrations of NaCl to the nutrient solution, while the control treatment was irrigated daily without NaCl. The results revealed a significant increase in the leaf number and fresh and dry weights of plants irrigated with 800 ppm salinity every four days. However, the highest chlorophyll content was consistently recorded in the control treatment (0 ppm, 4-day irrigation interval), although no significant variability in chlorophyll content was observed at week 6. The highest yields of N, Mg, and Cu were consistently recorded in plants without saline treatment, while P, K, Ca, Na, Zn, and Fe were consistently recorded in plants subjected to a combination of salinity and irrigation intervals. The combination of salinity and irrigation intervals was significant for Fe and Ca, whereas, for other elements, no significant differences occurred. The salt concentration did not influence the high yields of acid detergent fibre (ADF), crude fat, protein, or neutral detergent fibre (NDF), as they were recorded in high amounts in plants subjected to irrigation intervals only, whereas a combination of salinity and irrigation intervals resulted in the highest ash and moisture contents. Invariably, the 8-day irrigation interval without salinity optimized the yields of assayed polyphenols, flavonols, Ferric Reducing/Antioxidant Power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH), suggesting that salt stress does not influence the quantities of phytochemicals and antioxidants of M. crystallinum. These findings suggest that M. crystallinum can minimize the impact of salt stress on the accumulated minerals, phytochemicals, and proximate and antioxidant substances. Therefore, it is a suitable vegetable for regions affected by both salinity and water stress, as it can provide additional minerals, phytochemicals, antioxidants, and proximate nutrients when cultivated in saline soils.

Wild leafy vegetables are commonly included in the diet of people in rural homesteads. Among various wild edible vegetables in South Africa, Trachyandra divaricata (Sandkool) is one of the most abundant but underutilized due to the dearth of literature on its cultivation and nutritional value. In the present study, the effect of potassium application and pruning on growth dynamics, mineral composition, and proximate and phytochemical content in T. divaricata were evaluated. Treatments consisted of three potassium concentrations (0.0072, 0.0144, and 0.0216 M) supplemented in the form of potassium sulphate (K₂SO₄) with four pruning levels (unpruned, 5, 10, and 15 cm) applied in each treatment. The potassium doses were added to the nutrient solution, while the control treatment was sustained and irrigated with nutrient solution only. The results revealed a significant increase in flower bud yield, height, total dry and wet weight of shoots and roots, as well as ash and neutral detergent fibre in plants irrigated with 0.0072 M of K₂SO₄ without pruning. Conversely, chlorophyll content and Ca were comparable among treatments, while the highest yield of Na, P, N, and Zn was recorded in treatment 100 mL of K₂SO₄ with 10 cm pruning. Likewise, the highest antioxidant value (Polyphenols, Flavonol and DPPH) was obtained from plants irrigated with 0.0072 M of K₂SO₄ with 10 cm pruning. Based on these findings, T. divaricata is a promising leafy vegetable as a minimum dose (0.0072 M) of K with moderate pruning optimised its productivity in terms of growth, biomass parameters, nutritional content, and antioxidant potential. Due to its rich nutritional value, the plant should be domesticated and studied further for its potential nutraceutical benefits.

This study was designed to investigate the variations in alkaloid concentrations of Sceletium tortuosum when grown in soilless mediums under different fertigation regimes and to examine the suitability of the plant for hydroponic cultivation. A mother plant obtained from Verve Dynamics (Pty) Ltd (a manufacturer and supplier of purified botanical extracts) was cultivated into three hundred plants used for this research study. Twenty treatments were evaluated with 15 sample replicates. Treatments were made up of 4 different soilless growing media, namely: pure silica sand, 50% silica sand with 50% coco-peat, 50% silica sand with 50% vermiculite, and 50% silica sand with 50% perlite. These growing media were tested in conjunction with 5 different fertigation regimes (FR). Plants grown in FR1 received aqueous nutrient solution once every week, FR2 received aqueous nutrient solution once every second week, FR3 received aqueous nutrient solution once every third week, FR4 received aqueous nutrient solution once every fourth week and FR5 received aqueous nutrient solution once every fifth week respectively. Results from this experiment showed that different soilless growing media and fertigation had varying effects on alkaloid concentrations in S. tortuosum. It was also observed that roots contained higher amounts of delta 7 mesembrenone and mesembrenone, while shoots contained higher amounts of the alkaloid mesembrine.

This study evaluated the effect of salinity and soilless media on the vegetative growth, phytochemicals, and antioxidant capacity of Trachyandra ciliata (wild cabbage) to develop its growth protocol and explore its potential as a natural source of secondary metabolites. Treatments consisted of different concentrations of sodium chloride (NaCl), control- 0 mM, 100 mM, 200 mM, 400 mM, while different in vitro assays were used for phytochemical and antioxidant screenings. Findings from the study showed that low salinity (100 mM) significantly increased chlorophyll content, plant height, leaf number, plant fresh weight, and production of inflorescence, particularly in Peat-Perlite-Vermiculite (PPV) medium. In contrast, the control was the most productive treatment in plant dry weight except for the inflorescence. The highest antioxidant activity was observed in 200 mM of NaCl treatment in combination with PPV medium, which also produced the highest mean values for polyphenols, while 100 mM was the best for flavonols. Therefore, T. ciliata proved to be more productive vegetatively under low salinity in combination with PPV soilless media. A combination of 200 mM + PPV treatment was also recommended for maximum production of antioxidants for T. ciliata.