Charles Petrus Laubscher

• Doctor of Technology
• Professor (Associate) at Cape Peninsula University of Technology

Climate change, drought, and soil salinization present huge limitations to global agricultural output, which threatens food security. This necessitates the cultivation and domestication of wild edible halophytes as alternatives to mainstream food crops, especially in arid and semi‐arid regions. Trachyandra ciliata is one of the under‐researched and...

Global agriculture feeds over seven billion people and alarmingly, this number is expected to increase by a further 50% by 2050. To meet the additional food demand, the world development report has estimated that crop production should increase by 70–100% by 2050. However, climate change, expanding soil salinization, and the developing shortages of...

Biostimulants such as seaweed extracts are emerging as crop management products that can enhance crop productivity and nutritional quality under abiotic stress conditions. Therefore, this study aimed to assess the effectiveness of a seaweed-derived biostimulant (Kelpak ®) in alleviating salinity stress in spinach. A greenhouse experiment which cons...

The protracted natural bulb growth rate and offset generation constrain the timely expansion of bulbs in Amaryllis belladonna. An 18-month experiment was conducted to determine the efficacy of different root zone water temperatures and soilless media on the bulb yield and offset production of A. belladonna cultivated in a deep water culture hydropo...

Water scarcity and high salinity in agricultural lands pose serious threats to food security amid exponential population growth. This then necessitates the cultivation of salt- and drought-tolerant plant species as alternatives to mainstream vegetable crops. Previous studies have identified Trachyandra ciliata (wild cabbage) and other wild edible h...

Tetragonia decumbens is an edible halophyte that grows naturally in saline environment; however, its tolerance mechanisms are poorly understood for bio-saline agriculture. So, this research was designed to look into how salinity affects vegetative growth, leaf succulence, chlorophyll content, cation accumulation, oxidative stress indicators, and an...

Tetragonia decumbens is a neglected edible halophyte that grows naturally in coastal areas of South Africa. Its underutilisation is due to the limited literature on its nutraceutical potential. So, this research was designed to assess the nutritional value, secondary metabolites, and anti-microbial potential of wild and greenhouse cultivated T. dec...

Background: The wild population of Hypoxis hemerocallidea continues to decline rapidly because of overharvesting for medicinal use. This has necessitated the development of sustainable cultivation protocols for the species to promote its conservation. Aim: The impact of varying concentrations of compost tea extract on the growth, nutrient, antioxid...

Organic horticulture is a holistic management system that follows good production practices and should be considered the cornerstone of mitigating climate change and producing healthier fruits and vegetables. This agroecosystem practice not only benefits the green economy but promotes and enhances soil biological activity, biodiversity, and other b...

AbstraIncorporating knowledge of indigenous forage legumes or associated nutritional attributes in cultivated pastures has the potential to improve grazing conditions, rangeland conditions, and cattle productivity. Climate change and other site-specific factors such as land sizes and other grazing management practices play a significant role in foo...

The purpose of this review is to investigate the role of legume cover crops in improving climate adaptability and water use efficiency in South African grassland systems. Climate change is posing significant obstacles to agricultural systems all over the world, which includes South Africa, where shortages of water and fluctuations are significant i...

This study investigated the ethnobotanical uses of Afzelia africana Sm. ex Pers., a threatened tree species in Nigeria to determine the impact of uses of this species on the risk of its extinction. Ethnobotanical surveys were conducted by means of semi-structured questionnaires with the local community called Ijebu Igbo in Ogun state of Nigeria and...

The development of antiretroviral therapy has brought a tremendous relief to the world as it minimizes mortality, reduces HIV transmission, and suppresses progression in infected patients. However, the orthodox antiretroviral therapy is faced with limitations which have necessitated a continuous search for more novel plant-based antiviral compounds...

Amaryllis belladonna is an autumn-flowering bulbous geophyte endemic to the Western Cape, South Africa. The species’ erratic flowering disposition and brief flowering period upon maturity limit its economic productivity and competitiveness within the traditional genera of cut flowers and potted plants. However, it can be an attractive, eco-friendly...

Tetragonia decumbens Mill. has recently been reported to withstand the adverse effect of salinity. However, its leaf anatomical responses are poorly understood since previous studies were focused on basic physiological and biochemical parameters. This study was designed to examine leaf micromorphological traits and internal leaf elemental compartme...

Mesembryanthemum crystallinum L. is an annual halophyte that originated from southern Africa. However, little has been reported about factors that modulate the quantity of secondary metabolites in the plant. In this study, the twin effect of different nitrogen concentrations (0.36, 0.6, 0.8 g/L) and growing media (LECA clay, peat, vermiculite and s...

Abstract: 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 phytoc...

Pelargonium tomentosum Jacq. (Geraniaceae) is a herbaceous peppermintscented groundcover native to the Western Cape of South Africa. This study measured the adaptability and vegetative growth of P. tomentosum to various sub-optimal levels of dissolved oxygen (DO) in deep water culture hydroponics over 74 days. Four different methods of oxygenation...

The wild population of Siphonochilus aethiopicus (Zingiberaceae) is being eroded due to several pharmacological benefits and the hidden economy credited to its ethnobotanical uses in Southern Africa. This has called for the adoption of sustainable ways of cultivating the species without compromising its bioactive constituents. In this study, compos...

Pelargonium reniforme Curtis and Pelargonium sidoides DC are medicinally important plants of the large family Geraniaceae and indigenous to the southern areas of Africa. Both species are small shrublets or sub-shrubs whose tuberous roots contain essential metabolites used for the treatment of several diseases. The efficacy of these two species has...

Justicia secunda Vahl belongs to the family Acanthaceae. The plant was primarily cultivated for ornamental purposes before the discovery of its medicinal uses for the treatment of chronic diseases threatening public health. In the present study, extraction of the leaves of the plant was carried out using organic solvents (acetone, chloroform and et...

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. di...

Tetragonia decumbens is a neglected wild vegetable in South Africa. The dearth of literature on its propagation and cultivation methods has led to its underutilization. This prompted an investigation on the vegetative propagation of T. decumbens as influenced by rooting media and indole-3-butyric acid (IBA) treatment to formulate a viable propagati...

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 applicati...

Asteraceae annuals from South Africa’s winter-rainfall region often exhibit poor germination, and it is a challenge to establish a garden display using fresh seeds from the wild. Arctotis hirsuta (Harv.) Beauvard is a popular ornamental, Oncosiphon suffruticosum (L. Bolus) K. Bremer & Humphries is important in traditional medicine, and Cotula ducki...

The choice of hydroponic systems for fodder production is of great importance to Sub-Saharan Africa and specifically South Africa, considering the current water crisis. This study investigated the impacts of seed soaking times and irrigation frequency on the vegetative and nutritive properties of Hordeum vulgare grown in a hydroponic room. H. vulga...

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 a...

security and nutrition and promote sustainable crop production by 2050. However, climate change, increasing soil salinization and the inadequate availability of fresh water have negatively affected crop production around the world including South Africa, making it difficult to meet the required target. This necessitates the use of wild edible plant...

Female and male plants of difficult-to-root species Leucadendron elimense subsp. elimense were investigated for rooting potential with three rooting hormones: indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA), and indole-3-butyric acid (IBA) at three different concentrations (2000 ppm, 4000 ppm, and 6000 ppm). The experiment was made under...

Overdependence on exotic plant species constitutes a major setback for the consumption of wild fruits and vegetables among South Africans. The country is not spared from the adverse effects of climate change which play a substantial role in altering the ecosystem and have a ripple effect on food security. Wild fruits and vegetables have been identi...

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), con...

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 mi...

Sceletium tortuosum is a succulent plant that belongs to the family Mesembryanthemaceae (Aizoaceae). It is indigenous to South Africa, where it is well known by the indigenous people, especially in Namaqualand where the plant is utilized regularly for its medicinal and psycho-active properties. The main alkaloids responsible for these properties ar...

Streptocarpus formosus (Hilliard & B.L. Burtt) T.J. Edwards is a flowering herbaceous perennial indigenous to South Africa and is part of the rosulate group of herbaceous acaulescent plants within the Gesneriaceae family. According to the National Assessment database for the Red List of South African Plants version 2020.1., the plant is listed as r...

This study was designed to investigate the growth characteristics, chlorophyll content and nutritional properties of Tetragonia decumbens, an indigenous plant species of the South African Western Cape. One hundred and eight cuttings generated from a mother plant obtained from a garden were cultivated in hydroponic systems over 7 weeks. The hydropon...

This study was designed to investigate the variations in alkaloid concentrations of Sceletium tortuosum when grown in soilless media 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 extr...

Amaryllis belladonna is an indigenous bulb endemic to the southwestern Cape of South Africa and one of two members of the Cape genus. It is closely linked to the Brunsvigia and Nerine bulbous species. This bulb has a hysteranthous nature of showcasing the arrival of white to different shades of pink scented trumpet-shaped flowers in late summer to...

An understanding of initiation and influencing factors are necessary to develop forcing techniques for flowering plants. The March lily (Amaryllis belladonna) is a late summer flowering bulbous plant of South Africa. The inflorescence bears 2-12 soft pink fragrant funnel-shaped flowers on 'naked' (leafless) stems. It makes an excellent potted plant...

Pelargonium tomentosum Jacq.; the peppermint-scented pelargonium, is an herbaceous groundcover indigenous to the Western Cape of South Africa. Volatile oils are produced by this plant, which are used in the fragrance industry. Studies on other Pelargonium species have shown chlorophyll content may affect the yield of essential oils. This study was...

Salvia chamelaeagnea (Lamiaceae) is a slow growing water‐wise evergreen shrub originating from the western province of South Africa. It is an attractive landscape, and S. chamelaeagnea is a medicinal plant. It is important to develop enhanced cultivation protocols that could result in high yield and high‐quality medicinal materials. Chlorophyll is...

The effect of drip irrigation regimen on growth, physiological parameters, and crop yield in Cucumis sativus L. was investigated using a drip irrigation system. The experimental design comprised eight various water regimens (2, 4, 6, 8, 10, 12, 14, and 16 L·h–1). Plants received water five times a day, making a total of 10, 20, 30, 40, 50, 60, 70,...

Leonotis leonurus (L.) R.Br.; Lamiaceae is an indigenous southern African plant of commercial interest, which grows up to 3 m tall and 1.5 m wide, thus making it difficult to cultivate for the potted flowering plant industry. We tested different rates of a growth retardant paclobutrazol for retarding vegetative growth of L. leonurus for use as a fl...

The traditional African medicinal plant Salvia chamelaeagnea has shown potential as a clinical medicinal crop, but there has been little investigation into the ideal cultivation techniques and conditions for production. This study investigated the effects of supplementary phosphorus and different pH levels on the growth and development of Salvia ch...

The chemical composition of aquatic habitat, environmental conditions and trend monitoring could reflect changes in species composition over time. Vegetation plays an important role in decontamination and waste treatment water inlet and received by wetlands. They provide carbon substrate for microbes which are important in processing wastewater con...

The effects of various quantities of water were assessed on their potential to influence the content of flavonoid and anthocyanin contents in different tissues of cucumber plants grown hydroponically in the greenhouse. The treatments included supplying eight different water quantities 2, 4, 6, 8, 10, 12, 14 and 16 L/h. The plants received water fiv...

The assessments of photosynthetic rate, stomatal conductance, evapotranspiration, intercellular CO 2 concentration and chlorophyll content in Beta vulgaris subsp. cycla ‘Fordhook Giant’ grown in hydroponic cultures containing different compositions of hydroponic solutions were evaluated in this study. The aim of the study was to quantify the effect...

The Agulhas Plain contributes largely to the commercial Protea cut flower industry in South Africa. The illegal field harvesting of Red Data species such as Leucadendron elimense subsp. elimense, L. laxum, L. platyspermum and L. stelligerum (Protaceae) has drastically reduced their population numbers. Agricultural practices and a lack of conservati...

The aim of this study was to investigate the use of antioxidants, wounding treatments and hormone concentrations in efforts to overcome phenolic oxidation and stimulate axillary bud proliferation. Significant results were achieved with 1-naphthalene acetic acid (NAA) and 6-benzylaminopurine (BAP) concentrations on explants discoloration and callus...

The antioxidant content, capacity and certain oxidative stress parameters were investigated in salinity stressed Lactuca sativa L. 'Eish!' with the addition of exogenous silicon (Si). No significant changes were shown for total polyphenol concentrations in any of the experimental plants. Applications of 4 mM Si significantly increased oxygen radica...

The aim of this study was to determine the effects of antioxidant treatments, plant growth regulators (PGRs) and explants wounding in tissue culture involving Strelitzia reginae on total phenol exudation. Results showed that various 1-naphthalene acetic acid (NAA) and 6-benzylaminopurine (BAP) concentrations significantly affected phenolic exudatio...

The effects of 30 and 60 mM NaCl on Lettuce (Lactuca sativa L. 'Eish!'), grown in soilless culture, with additions of 0, 1, 2 and 4 mM Si was evaluated. Height, leaf number, weight, chlorophyll content and elemental analysis of plants were examined. Fresh root and shoot weight significantly increased with additions of 2 mM Si compared to that of th...

The comparisons of plant height, leaf number, foliage colour, fresh and dry weight of Beta vulgaris subsp. cycla 'Fordhook Giant' were evaluated in the glasshouse over a period of 8 week. The B. vulgaris plants were exposed to different nutrient solutions in which some contained Azolla filiculoides. Each treatment was replicated four times. The aim...

The effects of different temperature regimes of hydroponic solution on the chlorophyll pigmentation and photosynthesis of Ornithogalum longibracteatum L. were determined in the glasshouse for 10 weeks in 2009 and 2010. The plants were irrigated with hydroponic solution, heated to various temperatures (26, 30 and 34°C) via pumps connected to 4 sets...

The optimal media composition for the in vitro germination of isolated Strelitzia reginae embryos was investigated. Different media treatments were compared to determine the effects of MS medium strength, activated charcoal (AC) and vitamin supplementation on the germination and seedling development of immature Strelitzia embryos. Results indicate...

Water temperature can affect many physiological processes during plant growth and development. Temperatures below or above optimum levels may influence plant metabolic activities positively or negatively. This may include accumulation of different metabolites such as phenolic compounds, reactive oxygen species (ROS), nutrient uptake, chlorophyll pi...

Strelitzia spp. are highly valued as cut flowers and are of significant commercial value. Despite high demands, they have not been widely spread due to production constraints and are one of the few important cut flower plants for which no uniform cultivars are available. The conventional methods of propagation are very slow due to the plants low ra...

Vermicompost contains plant nutrients including N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu and B, the uptake of which has a positive effect on plant nutrition, photosynthesis, the chlorophyll content of the leaves and improves the nutrient content of the different plant components (roots, shoots and the fruits). The high percentage of humic acids in vermic...

In this study the effect of varying levels of pH on the fresh and dried yield and chlorophyll content of Artemisia afra Jacq. was investigated. Five groups of plants received deionised water adjusted to a certain pH. The pH for the treatments were 4.5, 5.5, 6.5 (the control), 7.5, and 8.5. The fresh weight of the plants was highest for the pH treat...

Pink dombeya (Dombeya burgessiae) was tested for its potential as a flowering potted plant, using the growth retardant Cycocel® (2-chloroethyl)-trimethylammonium chloride. The treatments included a control, 0.5, 1, 2 and 3 mg/L of Cycocel® per pot and were applied when seedlings reached 7 -8 cm in height. All treatments significantly reduced plant...

A hydroponic trial was carried out to assess the effect of inoculating tomato plants with AM fungi, in the presence and absence of a mycorrrhizal stimulant (Mycotech). Four treatments were applied: (1) AM inoculant, (2) mycorrhizal stimulant, (3) AM + Stimulant and (4) Stimulant alone. Arbuscular mycorrhizal treated plants were 14% root colonized,...

Gladiolus tristis (ever-flowering gladiolus) was tested for its potential as a flowering potted plant, using the growth retardant paclobutrazol. The treatments included a control, 2, 4, 8 and 16 mg active ingredient (a.i.) per pot and were applied when the longest leaves reached 15 cm. All treatments reduced perpendicular leaf height. Inflorescence...

Large parts of the Agulhas Plain (AP) contribute to the commercial export cut flower industry of South Africa while many threatened and endemic species are destroyed by local authorities and cut flower harvesters. The Western Cape is the largest area where threatened Red Data species are not at all known and the illegal harvesting of these species...

The effects of different temperature regimes of irrigation water on the growth rate of Spinacia oleracea L. were determined in the greenhouse for 8 weeks. The spinach seedlings were irrigated with water heated to various temperatures (24, 26 and 28°C) via pumps connected to 4 sets of water tanks each maintained at the experimental temperatures usin...

Large parts of the Agulhas plain contribute to the commercial cut flower export industry. However, this industry is causing the destruction of many Proteaceae species both endemic and threatened. The Agulhas plain is a large region (34°5000S 20°0009.15E / 34.833333°S 20.0025417°E) where threatened red data species are not sufficiently valued as man...

The popular cut flower, Leucadendron laxum (Marsh rose Leucadendron) was tested for its rooting ability, using various Indole-3-butyric acid (IBA) liquid hormone concentrations with different growth mediums. The IBA treatments included a control, 500, 1000, 2000 and 4000 ppm IBA auxins. Growth mediums tested were a) peat and polystyrene; b) bark an...

The effects of different concentrations of IAA exogenously applied to Proteaceae plants of the genus Leucadendron laxum on a variety of rooting medium were studied. The aim of the study was to evaluate the rooting response of tip cuttings of nature-grown shrubs using an intermittent mist propagation system in a shaded tunnel. The IAA treatments inc...

Vegetative propagation techniques were studied for rooting cuttings of the following South African tree species: Ficus sur, Olea europaea subsp. africana, Podocarpus falcatus (see Afrocarpus falcata and A. gracilior), and Syzygium cordatum. These tree species are considered problematic since they produce unwanted fruits in urban areas which attract...

Leucadendron laxum (Marsh rose Leucadendron) was tested for its rooting ability as an endangered plant species for reintroduction into the natural habitat, using IBA liquid hormone preparations and four growth media. The treatments included a control, 500, 1000, 2000 and 4000 ppm concentrations. Four growth media, namely: bark and polystyrene; peat...

The Agulhas Plain contributes largely to the commercial indigenous cut flower industry of South Africa. The Plain is rich in biodiversity and harbours many endemic species, some of which are threatened with extinction due to over-exploitation. Commercial plantations have increased but many species of Proteaceae continue to be harvested from the nat...