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Item Different postharvest responses of fresh-cut sweet peppers related to quality and antioxidant and phenylalanine ammonia lyase activities during exposure to light-emitting diode treatments(MDPI, 2019-08-23) Maroga, Gludia M.; Soundy, Pu y; Sivakumar, DhariniThe influence of emitting diode (LED) treatments for 8 h per day on functional quality of three types of fresh-cut sweet peppers (yellow, red, and green) were investigated after 3, 7, 11, and 14 days postharvest storage on the market shelf at 7 C. Red LED light (660 nm, 150 mol m2 s1) reduced weight loss to commercially acceptable level levels (2.0%) in fresh-cuts of yellow and green sweet peppers at 7 and 11 d, respectively. Blue LED light (450 nm, 100 mol m2 s1) maintained weight loss acceptable for marketing in red fresh-cut sweet peppers up to 11 d. Highest marketability with minimum changes in color difference (DE) and functional compounds (total phenols, ascorbic acid content, and antioxidant activity) were obtained in yellow and green sweet pepper fresh-cuts exposed to red LED light up to 7 and 11 d, respectively, and for red sweet pepper fresh-cuts exposed to blue LED light for 11 d. Red LED light maintained the highest concentrations of carotene, chlorophyll, and lycopene in yellow, green, and red sweet pepper fresh-cuts up to 7 d. Similarly, blue LED light showed the highest increase in lycopene concentrations for red sweet pepper fresh-cuts up to 7 d. Red LED (yellow and green sweet peppers) and blue LED (red sweet pepper) lights maintained phenolic compounds by increasing phenylalanine ammonia lyase activity. Thus, the results indicate a new approach to improve functional compounds of different types of fresh-cut sweet pepper.Item Socio-economic factors influencing smallholder farmers’ decision to participate in agro-processing industry in Gauteng province, South Africa.(Taylor and Francis, 2019-09-09) Khoza, T.M.; Senyolo, G.M.; Mmbengwa, V.W.; Soundy, P.Smallholder farmers in South Africa have not been linked successfully to sustainable agro-processing value chains. This study aimed to identify factors influencing smallholder farmers’ decision to participate in the agro-processing industry, as well as the extent of their participation in the Gauteng Province. Data was collected through a structured questionnaire that was administered face-to face to respondents in a randomly purposive selected sample of 102 smallholder farmers. A double-hurdle model was used to analyse factors influencing the decision to participate and the level of participation in agro-processing. The results show that very few (19%) smallholder farmers participate in the agro-processing industry of the Gauteng Province. The results also revealed that factors such as educational level, land tenure, agro-processing training and information have a positive influence on the decision to participate. Distance to market and off-farm income negatively influence the decision to participate. The level of participation is influenced by socio-economic factors such as age, household size, level of education, grain and livestock producers, farm size and access to training. The study recommends that smallholder agro-processing policy instruments be adjusted to facilitate effective participation in the agro-processing industry and participation in other high market value chains. There is a need to build up local agro-processing plants as a strategy of lowering the costs of transportation and storage when farmers take their farm produce to distant manufacturers or processors.Item Postharvest responses of hydroponically grown lettuce varieties to nitrogen application rate.(Elsevier Ltd., 2019-01-30) Mampholo, Bevly M.; Maboko, Martin; Soundy, Puffy; Sivakumar, DhariniLimited information is available on the influence of preharvest N application rates on postharvest quality of different lettuce genotypes. Two green leafy lettuce (Multigreen 1 and Multigreen 3) and red leafy lettuce (Multired 4) were grown in gravel film technique and fertigated with five different N application rates: 60, 90, 120, 150 and 180 mg L–1. The 120 mg L–1 N application is commercially recommended for lettuce. After harvest, lettuce samples were packed in a bioriented poly propylene packaging (5% O2 and 5% CO2) and held at 5°C and 85% RH for 3, 6, 9 and 12 days. The genotypes, preharvest N application rates and storage time affected the leaf colour coordinates, phenolic acids (dicaffeoyltataric acid, caffeoyl tartaric acid, 3-caffeoylquinic acid and 3,4-dihydroxycinnamic acid) and browning enzyme activities (phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD)). Lower rates of N application at preharvest stage showed higher weight loss with the storage time increasing in Multigreen 3. In Multigreen 1, colour coordinate b* value decreased remarkably with N application rates from 60 to 120 mg L–1 due to the onset of browning during storage. While in Multigreen 3 and N application higher than 60 mg L–1 influenced the decrease in b* value. Browning occurred due to the increased activity of PAL enzyme and the availability of the substrates caftaric, chlorogenic, caffeic acids, PPO activity and production of browning pigments due to the activity of POD. Higher, N application rates (>120 mg L–1) influenced the browning mechanism and showed brownish red leaves in Multired 4 during storage. Higher ascorbic acid concentration played a role in reducing the onset of browning in the fresh cuts leaves of Mulitired 4 and Multigreen 3 fertilized with lower preharvest lower N application rates (<120 mg L–1). Preharvest N application at 90 mg L–1 retained the colour, ascorbic acid content and the phenolic acid components and extended the shelf life of Multired 4 lettuce up to 6 days.Item The potential of rhizobacteria to mitigate abiotic stress in lessertia frutescens(MDPI, 2023-01-03) Hlongwane, Mokgadi M.; Mohammed, Mustapha; Mokgalaka, Ntebogeng S; Dakora, Felix D.Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative ability of the medicinal plant is attributed to its rich phytochemical composition, including amino acids, triterpenoids, and flavonoids. A literature review of some of the phytochemical compounds, particularly amino acids, in L. frutescens shows a steady decrease in concentration over the years. The reduction of the phytochemical compounds and diminishing biological activities may be attributed to drought and salt stress, which South Africa has been grappling with over the years. Canavanine, a phytochemical which is associated with the anticancer activity of L. frutescens, reduced slightly when the plant was subjected to salt stress. Like other legumes, L. frutescens forms a symbiotic relationship with plant-growth-promoting rhizobacteria, which facilitate plant growth and development. Studies employing commercial plant-growth-promoting rhizobacteria to enhance growth and biological activities in L. frutescens have been successfully carried out. Furthermore, alleviation of drought and salt stress in medicinal plants through inoculation with plant growth promoting- rhizobacteria is well documented and effective. Therefore, this review seeks to highlight the potential of plant-growth-promoting rhizobacteria to alleviate the effect of salt and drought in Lessertia frutescens.Item An assessment of symbiotic Nnutrition in species of the genus Aspalathus endemic to the Cape Floristic Region of South Africa(Elsevier B.V., 2023-05-26) Pampa, Joshua M.; Ngwenya, Zanele D.; Mpai, Tiisetso; Dakora, Felix D.Nitrogen fixation is important for the growth and yield of nodulated legumes. In this study, the 15N naturalabundance technique was used to assess the symbiotic N nutrition of 15 Aspalathus species sampled from 13locations. The results showed that all 15 species met part of their N requirements from N2 fixation, as shownby the different levels of symbiotic dependency. Seven species, for example, derived 54 to 77% of their Nnutrition from symbiosis, nine obtained 36 to 49% from fixation, and five species derived ˂ 20% of their Nfrom the atmosphere. More specifically, A. acuminata and A. clada both from Worcester Langerug derived76.5% and 72.1% N, respectively, from symbiosis, A. acuminata from Rondebosch obtained 68.4% N, A. acumi-nata from Kalbaskraal 59.5% N, A. aculeata from Mamesbury 56.8% N, A. divericata from Penhill 56.6% N and A.cordata from Dutoitkloof 53.9% N from the atmosphere. In contrast, A. zeyheri sampled from Kokrivier derived only 4.3% of its N from symbiosis, followed by A. capensis (13.3%) and A. carnosa (14.6%) both from Silverline's C/N values found for the Aspalathus species in this study were unusually high for a legume, and could suggest an ecological adaptation to the low N soils of the Cape fynbos as under such N-poor plants metaboli-cally switch from N-containing storage compounds to N-free storage molecules such as sucrose and glycerol, glucosides, galactoses and disaccharides.Item African leafy vegetables in South Africa.(Water SA, 2007-01-01) Jansen van Rensburg1, W.S.; Van Averbeke, W.; Slabbert, R.; Faber, M.; Van Jaarsveld, P.; Van Heerden, I.; Wenhold, F.; Oelofse, A.In this article the term ‘African leafy vegetables’ was adopted to refer to the collective of plant species which are used as leafy vegetables, and which are referred to as morogo or imifino by African people in South Africa. Function is central in this indigenous concept, which is subject to spatial and temporal variability in terms of plant species that are included as a result of diversity in ecology, culinary repertoire and change over time. As a result, the concept embraces indigenous, indigenised and recently introduced leafy vegetable species, but this article is concerned mainly with the indigenous and indigenised species. In South Africa, the collection of these two types of leafy vegetables from the wild, or from cultivated fields where some of them grow as weeds, has a long history that has been intimately linked to women and their traditional livelihood tasks. Among poor people in remote rural areas the use of these types of leafy vegetables is still common but nationwide there is evidence of decline, particularly in urban areas. Cultivation of indigenous or indigenised leafy vegetables is restricted to a narrow group of primarily indigenised species in South Africa. Seven groups of indigenous or indigenised African leafy vegetables that are important in South Africa were given special attention and their local nomenclature, ecology, use and cultivation are discussed.Item Deficit irrigation on growth of baby spinach (Spinacia oleracea L.) cultivars grown in varied-textured soils.(American Society for Horticultural Science, 2022-03-08) Lekgoathi, Boitumelo Patience; Soundy, Puffy; Kgopa, Pholosho MmatekoWater scarcity coupled with an increasing demand for water in agriculture has forced farmers to amend their irrigation practices and water management strategies. The proposed study was aimed at evaluating physiological and growth traits [photosynthesis rate, stomatal conductance (gS), chlorophyll content, leaf area, and fresh weight] under three irrigation levels (50%, 75%, and 100% of field capacity) in five varied textured soils (clay, clay loam, loam, sandy loam, and sandy). Response was evaluated on two baby spinach (Spinacia oleracea L.) cultivars (Dash and Hellios). Regarding physiological parameters, there were no interaction effects of deficit irrigation (DI) × soil texture. Significant increase on growth parameters (chlorophyll content, leaf weight, and leaf area) were observed under the interaction of 75% DI × sandy loam and loam soils on both ‘Dash’ and ‘Hellios’ during Season 1. ‘Hellios’ was able to adapt to deficit level of 75% during both growing seasons (summer and winter) under sandy loam soils. The study indicated that 25% water can be saved under sandy loam and loam soils when cultivating baby spinach during winter conditions.Item Cultivar and postharvest storage duration influence fruit quality, nutritional and phytochemical profiles of soilless-grown cantaloupe and honeydew melons(MDPI, 2022-08-17) Pulela, Boitshepo L.; Maboko, Martin M.; Soundy, Puffy; Amoo, Stephen O.There is an increasing demand for sweet melon (Cucumis melo L.) fruit in fruit and vegetable markets due to its nutritional content, resulting in different cultivars being grown in different production systems. This study evaluated the nutritional and phytochemical contents of soilless grown cantaloupe and honeydew sweet melon cultivars at harvest and postharvest. At harvest, vitamin C and -carotene concentrations were higher in orange-fleshed (cantaloupe) cvs. Magritte, Divine, Majestic, Cyclone, MAB 79001, E25F.00185, E25F.00075 and Adore, compared to green-fleshed (honeydew) cvs. Honey Brew and Honey Star. The zinc (Zn), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) contents were higher in orange-fleshed compared to green-fleshed cultivars. Total phenolics content (TPC) in cv. E25F.00075 was the highest (2.87 mg GAEg1 dry weight). A significant, positive, correlation occurred between -carotene and Zn, P, K, Ca and Mg contents. Postharvest storage duration affected TPC and total soluble solid content. The interaction of cultivar and postharvest storage duration affected flavonoid, vitamin C and -carotene contents, free radical scavenging activity and fruit juice pH. Vitamin C and -carotene contents decreased with increased postharvest storage duration while flavonoid content increased. The cantaloupe cultivars performed significantly better compared to the honeydew cultivars as evident in their high mineral element content, and vitamin C and -carotene concentrations. Selection of appropriate cultivars in a production system should consider variation in nutritional traits of cultivars and postharvest storage duration. Soilless production of sweet melon cultivars in tunnels offers a viable alternative to open field to produce high-quality melons at harvest and postharvest.Item Biomass, essential oil yield, and composition of marjoram as influenced by interactions of different agronomic practices under controlled conditions.(MDPI, 2022-12-30) Malaka, Mantwampe Johleen; Araya, Nadia Alcina; Soundy, Puffy; Du Plooy, Christian Phillipus; Araya, Hintsa Tesfamicael; Jansen Van Rensburg, Willem Sternburg; Watkinson, Eric; Levember, Ellis; Wadiwala, Ebrahim; Amoo, Stephen OluwaseunOriganum marjorana L. has been valued for centuries for its flavoring attributes and therapeutic properties. The growing demand for its various applications necessitates optimizing agronomic practices for its production. A glasshouse pot trial was conducted to identify optimum agronomic practices for increased herbage and oil yield, as well as oil quality. The effects of varying air temperature regimes (low, medium, and high levels), irrigation (low, medium, and high levels), nitrogen fertilizer application (N = 100, 150, and 200 kg/ha), and soil type (sandy loam, sandy clay loam, and loamy sand) on the productivity of marjoram plants were investigated. The results showed an increase in plant growth and herbage yield as well as chlorophyll content under conditions of high air temperature, low irrigation, and moderate to high nitrogen level applied to sandy loam soil, with an increase in oil yield with loamy sand soil. The major compounds observed in marjoram essential oil were terpinene-4-ol (22.63–36.72%) and (Z)- -terpineol (6.85–16.60%), in which terpinene-4-ol was not found to be within the International Organization for Standardization (ISO) limits of acceptability while (Z)- - terpineol had no reference limits available. A promising performance of marjoram cultivation under high regimes of air temperature (16.7 to 36.6 C), nitrogen fertilization (200 kg ha1 N), and low irrigation (up to 60% soil water depletion from field capacity) on sandy loam soils was demonstrated for improved crop productivity.