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.

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.

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Trachyandra divaricata (Sandkool) is one of the most abundant wild edible inflorescence vegetables in South Africa. The dearth of literature on its edibility, nutrient composition, and conservation has contributed to its underutilisation. This study investigated mineral and proximate content, phytochemical compositions, and growth response of T. divaricata to light intensity and soilless media. Treatments comprised four media (LECA clay, silica sand, peat, and vermiculite) which were subjected to different shade levels (no shade, 20, 40, 60, and 80%) created from a factory-made 20% density net by doubling (40%), tripling (60%), and quadrupling (80%). All treatments were irrigated with a standard nutrient solution. The results showed that the treatments impacted the yield of T. divaricata significantly in terms of biomass and flower buds, especially in plants cultivated in peat under normal greenhouse lighting (no shade). Conversely, plants developed significantly more specific leaf size and total chlorophyll content under shade levels (20, 40, 60, and 80%) in different growth media, even though the values were comparable among treatments. The highest Ca, Mg, Cu, Fe, and Mn levels were consistently recorded in flowers of T. divaricata grown in LECA clay under 80% shade level, while other minerals varied in tested treatments. The peat medium under 20% shade optimised the neutral detergent fibre (NDF) and acid detergent fibre (ADF) content of the flowers, whereas both fat and protein contents were greatly enhanced by peat and vermiculite, respectively, under the 80% shade. Consistently, the lowest phytochemical contents were recorded in LECA clay subjected to 80% shade, whereas the highest polyphenols and DPPH antioxidants were produced by silica sand medium treated with 20% shade. Both TEAC and FRAP antioxidants were improved significantly in LECA clay under no shade and the 60% shade level. However, both 20% and 60% shade levels enhanced the flavonol content significantly. On the basis of these findings, T. divaricata is a promising inflorescent vegetable that may be considered for domestication and further research due to its potential pharmacological and nutraceutical values.