Comparative Study of Sensory Attributes of Leafy Green Vegetables Grown Under Organic and Conventional Management

This study was carried out to compare the sensory qualities of leafy green vegetables (collard, kale, lettuce and swiss chard) grown under organic and conventional production systems. Four leafy greens were produced on an organically and conventionally managed research farm of Tennessee State University, Nashville, TN in Spring 2019 and 2020. Crops in a conventional field were grown in the open field, whereas in organic field crops were grown in the open and under three different row covers (agribon cloth, insect net and plastic). Row covers in organic systems were used to protect crops from insect damage. Plant samples were collected from all the treatments and evaluated for sensory qualities including color, texture, taste, odor and flavor following two approaches i.e., instrumental and via consumer panel perception. Consumer panel perception results showed minor differences in the sensory qualities between organic and inorganically produced leafy greens. Instrumental methods showed no differences in color parameters of kale, lettuce and swiss chard grown under organic and conventional production systems. In collard, the lightness (L*), b* (yellow-blue axis), brightness (Y) and chroma (C) values were higher in conventional, while hue angle was higher in organic (open). There were no differences in instrumental textural values of organically and conventionally grown leafy greens. Among row covers, the textural value of collard and kale was higher in open relative to row covers. The content of main quality contributors 1-Hexanol was higher in conventionally grown collard compared to organic (open). Aldehyde compound was higher in organically grown kale and trans-hex-2-enyl-acetate (Ester) compound was higher in conventionally grown kale. Monoterpenes were higher in organic lettuce and ketones were higher in conventionally grown lettuce. Overall, there were not many differences in the sensory qualities of leafy greens grown under organic and conventional production systems. Further comparative studies between organic and conventional systems on sensory qualities of leafy greens are needed.

Soil response to root-knot nematode management with wine vinasse in a solarised horticultural soil under glasshouse conditions

Summary The increasing interest in agroecological practices and the current consideration of agrarian soils as a sustainable resource are driving the development of new strategies to manage soil parasites and diseases. The application of organic matter from different sources to reduce plant parasites contributes to circular economy by applying by-products as soil organic amendments that reduce wastes. Wine vinasse (WV) is a by-product generated to obtain alcohol from wine by physical methods in distilleries. The aim of this study was to determine the potential of WV and its combination with animal manure (WV+M) as soil biodisinfestation products. For this, it was compared with a plastic-covered control to distinguish the biodisinfestation from solarisation effect. The crops tested consisted of a tomato-Swiss chard rotation under glasshouse conditions. Their effects on Meloidogyne incognita, soil fertility, nematode community and crop yield were assessed. The results obtained after two seasons showed a reduction of M. incognita galling in the root system of both crops. The immediate effect after the treatment application was a reduction in the abundance of nematodes and changes in the nematode-based indices that affected all plots, including the control, most likely related to the tillage effect for the treatments application and the plastic cover. Soil fertility was improved by the application of WV (NO3−, Bioav. P) and WV+M (C, Ntotal, K), which reduced herbivore nematode metabolic footprints and enhanced bacterivore footprints. Our results indicate that the combination WV+M was effective reducing M. incognita infection, and improved crop yield. Use of by-products such as WV is a helpful tool for managing horticultural soils.

The Urban Double-Crop: Can Fall Vegetables and a Warm-Season Lawn Co-Exist?

A gardening methodology using double-cropped cool-season vegetables and warm-season turfgrass, thereby capitalizing on the ideal growing season for each, was developed in field trials and tested in volunteers’ landscapes. Broccoli (Brassica oleracea’), lettuce (Lactuca sativa), and Swiss chard (Beta vulgaris subsp. Cicla) were planted into an established hybrid bermudagrass lawn (Cynodon dactylon (L) Pers. × C. transvaalensis Burtt-Davy ‘Tifsport’) in September. The vegetables were planted into tilled strips, 5 cm × 10 cm holes and 10 cm × 10 cm holes in the turf. All treatments produced harvestable yield, though the yield of vegetables planted in the tilled treatments and larger holes was greater than in smaller holes. Efforts to reduce turfgrass competition with vegetables by the application of glyphosate or the use of the Veggie Lawn Pod (an easily installed plastic cover on the lawn) did not increase yield. Tilled treatments left depressions that discouraged spring turfgrass recovery. The double-crop was tested by seven volunteers on their lawns. Though lawn-planted vegetables did not produce as much yield as those planted in the volunteers’ gardens, the volunteers were enthusiastic about this methodology. The volunteers reported that lawn vegetables were more difficult to plant but not more difficult to maintain, and they were easier to harvest than vegetables in their gardens. All volunteers reported satisfactory recovery of their lawns in the spring.

The localisation, intracellular transport, and biosynthetic regulation of betalain plant pigments

<p>This thesis investigates the localisation, transport and biosynthetic control of betalain plant pigments to compare with the extensively researched anthocyanins. Anthocyanins and betalains appear similar, yet no plant naturally contains both pigment types. Due to this mutual exclusivity, betalain pigments are thought to functionally replace anthocyanins in many Caryophyllales. However, minimal research has been conducted to support this replacement hypothesis, resulting in limited knowledge of betalain pigment distribution and biosynthesis. The following series of experiments have added to this body of knowledge. Localisation of betalains was compared with that reported for anthocyanins. Histological analyses of 12 different betalain-producing species revealed similar pigment localisation to that of anthocyanic species. Similarities in pigment localisation suggest that these pigment types may have similar functional roles. The histological analyses also found that betacyanins and betaxanthins had differential localisation in several taxa. Organ- or tissue-specific distribution of betalain compounds suggests differing biological functions for betaxanthins and betacyanins. Hypotheses on betalain transport were tested using transgenic Arabidopsis thaliana lines capable of producing anthocyanins (PAP1-5), betalains (DOD-6), or both (DOD-6 x PAP1-5). Betaxanthins appeared to use vesicular transport, as betaxanthins were detected in small circular bodies within the cytoplasm. Furthermore, this observation suggests that betaxanthin formation occurred outside of the vacuole. DOD-6 was also crossed with Arabidopsis mutants, tt12 and tt19, which are deficient in proteins required for flavonoid vacuolar transport. Betaxanthin accumulation was reduced in both lines. In addition, DOD-6 was treated with transport inhibitors that affect anthocyanin accumulation. These experiments demonstrated that betaxanthins can utilise known flavonoid transport mechanisms, at least in this artificial pigment system. Regulation of betalain biosynthesis was analysed using Swiss chard (Beta vulgaris subsp. cicla cv. ‘Bright Lights’). Betalain production was induced through physical wounding of the lamina in red and white Swiss chard lines. Betalain pigments were produced around the wounding sites in the red line but not in the white line. Transcript level changes of betalain and flavonoid biosynthetic genes in these tissues were measured using real-time quantitative polymerase chain reaction analyses. Betalain biosynthetic genes were not up-regulated in the red line even though red pigments visibly accumulated. Rather, these genes were already expressed in the red line prior to wounding. Biosynthetic control of betalains may either be earlier in the pathway or at the post-transcriptional level. In contrast, all three flavonoid biosynthetic genes were up-regulated in response to wounding, indicating that expression of flavonoid and betalain biosynthetic genes are not co-regulated in Swiss chard. The final set of experiments examined the function of the two Beta vulgaris DOD genes (DODA and DODA1). Both genes were transiently expressed in nivea Antirrhinum majus dorsal petals and vacuum infiltrated with the betalain precursor L-DOPA. Expression of DODA1 but not DODA appeared to produce betalains. DODA-like genes have been found in anthocyanin-producing species, suggesting that this gene may not be involved in betalain biosynthesis. The overall findings from this research indicate that betalain pigment evolution of may have involved the utilization of anthocyanin transport machinery, but the regulatory control of the two pathways appears different.</p>

The localisation, intracellular transport, and biosynthetic regulation of betalain plant pigments

<p>This thesis investigates the localisation, transport and biosynthetic control of betalain plant pigments to compare with the extensively researched anthocyanins. Anthocyanins and betalains appear similar, yet no plant naturally contains both pigment types. Due to this mutual exclusivity, betalain pigments are thought to functionally replace anthocyanins in many Caryophyllales. However, minimal research has been conducted to support this replacement hypothesis, resulting in limited knowledge of betalain pigment distribution and biosynthesis. The following series of experiments have added to this body of knowledge. Localisation of betalains was compared with that reported for anthocyanins. Histological analyses of 12 different betalain-producing species revealed similar pigment localisation to that of anthocyanic species. Similarities in pigment localisation suggest that these pigment types may have similar functional roles. The histological analyses also found that betacyanins and betaxanthins had differential localisation in several taxa. Organ- or tissue-specific distribution of betalain compounds suggests differing biological functions for betaxanthins and betacyanins. Hypotheses on betalain transport were tested using transgenic Arabidopsis thaliana lines capable of producing anthocyanins (PAP1-5), betalains (DOD-6), or both (DOD-6 x PAP1-5). Betaxanthins appeared to use vesicular transport, as betaxanthins were detected in small circular bodies within the cytoplasm. Furthermore, this observation suggests that betaxanthin formation occurred outside of the vacuole. DOD-6 was also crossed with Arabidopsis mutants, tt12 and tt19, which are deficient in proteins required for flavonoid vacuolar transport. Betaxanthin accumulation was reduced in both lines. In addition, DOD-6 was treated with transport inhibitors that affect anthocyanin accumulation. These experiments demonstrated that betaxanthins can utilise known flavonoid transport mechanisms, at least in this artificial pigment system. Regulation of betalain biosynthesis was analysed using Swiss chard (Beta vulgaris subsp. cicla cv. ‘Bright Lights’). Betalain production was induced through physical wounding of the lamina in red and white Swiss chard lines. Betalain pigments were produced around the wounding sites in the red line but not in the white line. Transcript level changes of betalain and flavonoid biosynthetic genes in these tissues were measured using real-time quantitative polymerase chain reaction analyses. Betalain biosynthetic genes were not up-regulated in the red line even though red pigments visibly accumulated. Rather, these genes were already expressed in the red line prior to wounding. Biosynthetic control of betalains may either be earlier in the pathway or at the post-transcriptional level. In contrast, all three flavonoid biosynthetic genes were up-regulated in response to wounding, indicating that expression of flavonoid and betalain biosynthetic genes are not co-regulated in Swiss chard. The final set of experiments examined the function of the two Beta vulgaris DOD genes (DODA and DODA1). Both genes were transiently expressed in nivea Antirrhinum majus dorsal petals and vacuum infiltrated with the betalain precursor L-DOPA. Expression of DODA1 but not DODA appeared to produce betalains. DODA-like genes have been found in anthocyanin-producing species, suggesting that this gene may not be involved in betalain biosynthesis. The overall findings from this research indicate that betalain pigment evolution of may have involved the utilization of anthocyanin transport machinery, but the regulatory control of the two pathways appears different.</p>

A survey of Nitrate and Nitrite Contents in Vegetables to Assess The Potential Health Risks in Kurdistan, Iraq

In this study, nitrate and nitrite contents were determined of a total (308) samples of 15 different types of vegetable such as leek, swiss chard, celery, spinach, garden cress, green onion, turnip, radish, aubergine, squash, tomato, pepper, cucumber, mint, and tarragon. They were taken from different fields located in Sulaymaniyah province: Sulaymaniyah city (Tanjarro and Kanaswra), Bazyan (Baynjan), Halabja (Said Sadiq), and Kalar (Grda Gozena). Using spectrophotometer measurements performed by UV/VIS double beam spectrophotometer at 538nm. The highest level of nitrate (529.55 mg/kg) for garden cress in Said Sadiq, (486.74 mg/kg) for Swiss chard in Kanaswra, and (477.65 mg/kg) for spinach in Bazyan. In addition, leek and celery contained high nitrate concentrations of about (416.65 and 447.60) mg/kg in Kanaswra and Bazyan, respectively. While the lowest nitrate concentration in fruiting vegetables like a tomato was 5.934 mg/kg in Bazyan, and aubergine in Grda Gozena was 5.617 mg/kg. Interestingly, the value of the Acceptable Daily Intake (ADI) and the Target Hazard Quotient (THQ) was lower than the standard limit, ADI for nitrate in this study was about (0.51, 2.18) mg/kg bw/day for adults and children, while the standard limit (3.70 mg/kg bw/day). Also, ADI for nitrite in this study was about (0.01, 0.05) mg/kg/bw for adults and children, while the standard limit was about 0 - 0.06 mg kg, as a result, the THQ ≤1. In summary, we can conclude that the amount of nitrates in raw vegetables was lower than the standard limit’s level and that this level does not cause health problems for consumers.

Effect of Substrate Flow Rate on Nutrient Uptake and Use Efficiency in Hydroponically Grown Swiss Chard (Beta vulgaris L. ssp. cicla ‘Seiyou Shirokuki’)

Unlike in soil culture, a substrate (nutrient solution) in a hydroponics system can flow, and this can affect both nutrient uptake and plant growth. In this study, we hydroponically cultivated Swiss chard (Beta vulgaris L. ssp. cicla) under different flow rates to analyze changes in the growth, nutrient uptake, and nutrient use efficiency. When the flow rate was intensified from 2 to 4 L/min, leaf area, the fresh weight, dry weight, and root length increased. However, when the flow rate was increased from 4 to 8 L/min, values of these growth parameters decreased. The nutrient uptake had a similar trend relative to the growth parameters and nutrient use efficiency of macronutrient elements, increased as the flow rate increased. This indicates that the flow rate affects plant growth by influencing the nutrient uptake, and an increase in the flow rate can aid in improving nutrient use efficiency. In hydroponics, regulating the flow rate at a reasonable volume is recommended to increase yield by enhancing nutrient use efficiency, but too intensive a flow rate may cause excessive physical stimulation to plants and inhibit their growth. Therefore, it is important to choose an appropriate substrate flow rate for optimal hydroponics production.

Mitigating salt accumulation in recycled brewery effluent through the integration of water treatment, agriculture and aquaculture

Water scarcity in South Africa, and globally, presents challenges for industries. It is imperative to develop responsible water use, such as recycling and reusing wastewater from food processing industries such as breweries. The Ibhayi Brewery (SAB Ltd) employs a combination of sustainable treatment processes that include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW) to treat brewery effluent on an experimental scale. The constituent concentrations of these experimentally treated effluents are within the ranges prescribed by local regulations to allow for potential downstream use in agriculture and aquaculture. However, the sodium content in this treated effluent, which originates from upstream cleaning agents and pH control at the onsite effluent treatment facility, is a constraint to the downstream use of brewery effluent. This study addresses the salt problem, by investigating the potential of either reducing/eliminating salt addition at source, or developing alternative techniques for downstream agriculture to mitigate the effects of salt accumulation caused by irrigation with brewery effluent. Four salt-tolerant test crops; Swiss chard (Beta vulgaris), saltbush (Atriplex nummularia), Salicornia meyeriana and sorghum (Sorghum bicolor), grew efficiently in brewery effluent irrigated soils but did not stop sodium accumulation in the growth medium. Swiss chard had the best growth with a wet biomass accumulation of 8,173 g m-2, due to the plant’s ability to tolerate saline conditions and continuous cropping. Crop rotation, to limit effects of nutrient depletion in soil, had no significant effect on plant growth suggesting soils were adequately able to provide micro-nutrients in the short-term. Prolonged irrigation with brewery effluent can lead to sodium accumulation in the soil, which was successfully controlled through the addition of soil amendments (gypsum and Trichoderma cultures). These reduced soil sodium from a potentially limiting level of 1,398 mg L-1 to the acceptable levels of 240 mg L-1 and 353 mg L-1 respectively, mainly through leaching. However only Trichoderma improved Swiss chard production to 11,238 g m-2. While crop rotation in this work did not contribute to mitigating the problem of salt accumulation, soil amended with Trichoderma appears to be a potential solution when brewery effluent is reused in agriculture. In an alternative to soil cultivation, CWs were trialled with no significant differences in the sodium concentration of brewery effluent treated along a 15 m lateral flow CW, which could be attributed to evapotranspiration. This was notably accompanied by a desirable 95.21% decrease in ammonia from inlet to outlet resulting in significant improvement in water quality for reuse in aquaculture where ammonia levels are important limiting constraints. While CWs remain a suitable brewery effluent treatment solution, this technology requires additional modelling and optimisation in order to mitigate the problem of salt accumulation in the reuse of treated brewery effluent in agriculture and aquaculture. This research demonstrates the baseline information for such modelling and optimisation. African catfish (Clarias gariepinus) grew in CW treated brewery effluent; however, this growth was moderate at 0.92% bw day-1, whereas Mozambique tilapia (Oreochromis mossambicus) were shown to be unsuited to growth in this system and lost weight with an average specific growth rate (SGR) of -0.98% bw day-1; and both fish species presenting with health related concerns. Hardy fish species such as African catfish can be cultured in brewery effluent, but with risk involved. This was a preliminary study to develop parameters for future dimensional analysis modelling to allow optimisation of the CW, based on nutrient removal rates obtained which will allow for improved downstream aquaculture by reducing or eliminating risks presented in this study. This work has also contributed to a foundation for the development of guidelines that use a risk-based approach for water use in aquaculture. Alternatives to the current in place cleaning agents were considered to mitigate the effects of salt accumulation. Sodium is introduced into the effluent via the use of sodium hydroxide and sodium chlorite for cleaning and disinfection in the brewery, as well as through effluent pH adjustment in the AD plant. The widespread use of outdated legacy cleaning systems and pH adjustment regimes is entrenched in the brewery standard operating procedures (SOP). A cost-benefit analysis (CBA) demonstrated that a change of cleaning and disinfecting regimes to hydrogen peroxide in the brewery, and magnesium hydroxide pH adjustment in the effluent treatment plant addresses the sodium issue upstream in the brewery practically eliminating sodium from the effluent. In addition, a life cycle analysis (LCA) was carried out to assess the environmental impacts associated with the alternative cleaning and pH adjustment scenarios. The LCA showed that electricity consumption during use phase of the chemicals for respective purposes, as well as their production activities were major contributors to the significant environmental impact categories that were assessed. The cleaning scenario employing the use of hydrogen peroxide for both cleaning and disinfection was found to be the most environmentally sustainable. This was attributed to the reduced number of chemicals used compared to the other cleaning scenarios. Dolomitic lime was the pH adjustment alternative with the lowest average environmental impact; but, however, had a higher impact on freshwater eutrophication which is of major concern if the effluent will be reused for irrigation. Magnesium hydroxide was therefore considered to be the better option as a sodium hydroxide alternative for pH adjustment. This mitigates salt accumulation, making treated brewery effluent suitable for reuse in high value downstream agriculture and aquaculture, while employing more environmentally sustainable technologies. Notably, this converts brewery effluent from a financial liability to Ibhayi Brewery, into a product containing water and nutrients that generate income, improve food security, and can create employment in downstream agriculture and aquaculture in a sustainable manner.