Browsing by Author "Sershen"

Now showing 1 - 6 of 6
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    Effects of exogenous application of five antioxidants on vigour, viability, oxidative metabolism and germination enzymes in aged cabbage and lettuce seeds
    (Elsevier B.V., 2021) Sershen; Adetunji, A.E; Varghese, B
    Ageing induces modifications capable of compromising seed vigour and viability. This study investigated the effects of exogenous application of five antioxidants: ascorbic acid (AA), gallic acid (GA), reduced glutathione (GSH), trolox and glycerol, on physical and biochemical lesions induced by controlled deterioration (CD) in Brassica oleracea (cabbage) and Lactuca sativa (lettuce) seeds. The antioxidants were applied at 0.2, 0.4 and 0.6 mM to fresh seeds and seeds subjected to CD: 75% viability (P75), 50% viability (P50) and 25% viability (P25); deionised water (DW) served as control. Controlled deterioration resulted in more abnormal seedlings production in cabbage than in lettuce seeds. Additionally, CD increased electrical conductivity (EC) and protein carbonylation (PC), lowered antioxidant and germination enzymes activities in both species but increased lipid peroxidation in lettuce seeds only. Exogenous application of antioxidants enhanced seed viability of cabbage at P25 and lettuce at P50 and P25; seedling vigour of fresh, P75 and P25 cabbage; P50 and P25 lettuce seeds. Electrolyte conductivity and lipid peroxidation were reduced by AA, GA, glycerol, GSH and trolox in lettuce seeds, while PC was reduced by GA, glycerol and GSH in both species.
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    Exogenous antioxidants enhance seedling growth and yield of artificially aged cabbage and lettuce seeds
    (MPDI, 2021) Adetunji, Ademola Emmanuel; Sershen; Varghese, Boby
    Aged seeds exhibit compromised vigour in terms of germination, seedling emergence and growth, but this can to some extent be alleviated by invigoration treatments before sowing. This study aimed to investigate ageing rates and patterns in cabbage (Brassica oleraceae) and lettuce (Lactuca sativa) seeds and whether the beneficial effects of invigorating aged seeds with exogenous antioxidants translate to enhanced seedling performance. Seeds were artificially aged to 25% viability before soaking in 0.4 mM glycerol, 0.6 mM GSH and 0.2 mM trolox for cabbage, and 0.6 mM glycerol, GSH and trolox for lettuce; deionised water served as a control. After 14 days of sowing, seedling emergence percentage, mean emergence time, mean daily emergence, and time taken to 25% emergence were computed. Seedling vigour index, root and shoot dry weight, root:shoot ratio, leaf area, leaf area ratio, and leaf chlorophyll content were assessed 6 weeks after sowing. Furthermore, the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), and chlorophyll fluorescence were measured 6 weeks after sowing. Notably, ageing resulted in the loss of seed vigour and viability at higher rates in lettuce than cabbage. Seed pretreatment with glycerol promoted seedling growth in both species and shoot dry weight in lettuce, while glycerol and GSH enhanced Pn, Gs and E in lettuce.
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    Forest canopy gaps offer a window into the future: The case of subtropical coastal forests within an urban matrix in South Africa
    (INST NACIONAL INVESTIGACION TECHNOLOGIA AGRARIA ALIMENTARIA, 2021) Bhugeloo, Astika; Ramdhani, Syd; Sershen
    Alien and indigenous species emergence patterns within canopy gaps in urban subtropical forests are poorly understood. This study compared canopy gap floristics in relation to abiotic and physical characteristics across three subtropical urban forests differing in disturbance history. : Three Northern Coastal Forests of varying disturbance histories located in coastal subtropical urban KwaZulu-Natal (KZN), South Africa (SA). Closed canopy (n = 15 quadrats per forest ) and four gaps (n = 12 quadrats per forest) from three size classes (‘small’ < 25 m2 , ‘medium’ 25 - 45 m2 ; ‘large’ > 45 m2 ) were surveyed for the primary least disturbed (PLD), primary highly disturbed (PHD) and transitional highly disturbed (THD) forests using classical vegetation sampling techniques. Soil moisture content and air temperature were measured within each gap.
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    How much leaf area do insects eat? A data set of insect herbivory sampled globally with a standardized protocol
    (Ecological Society of America, 2021) Sershen; Mendes, G.M; Silveira, F.A.O
    Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species.
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    Pineapple stem-derived bromelain based priming improves pepper seed protein reserve mobilization, germination, emergence and plant growth
    (Springer, 2021) Perez, Lianny; Acosta, Yanier; Sershen
    Pepper seeds are slow to germinate and emergence is often non-uniform and incomplete, reducing gains from this cash crop. This study investigated the effects of pineapple stem- derived protease (stem bromelain) based priming on pepper seed germination in relation to reserve mobilization (specifically, proteins and amino acids), germination, emergence and plant growth. These parameters were compared across two controls, (1) unsoaked seeds and (2) seeds soaked in deionized water, and seeds soaked in pineapple stem bromelain crude extract (treatment). Seeds were soaked in bromelain crude extract possessing a proteolytic activity of 6.25 tU or deionized water (first control) for 3 h at 35 C. Light microscopy revealed an abundance of protein bodies in the endosperm of the seeds prior to imbibition.
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    Quantification and characterisation of microplastics ingested by selected juvenile fish species associated with mangroves in KwaZulu- Natal, South Africa
    (Elsevier, 2020) Naidoo, Trishan; Sershen; Thompson, Richard C.
    Though the number studies on microplastic ingestion by fish is growing, data on fish species charac- teristic of the South African coastline are scarce. This study quantified and characterised (physically and chemically) microplastics ingested by four species of juvenile fish (viz. Oreochromis mossambicus [Peters, 1852], Terapon jarbua [Forsskål, 1775], Ambassis dussumieri [Cuvier, 1828] and Mugil sp.), within four mangroves along the east coast of South Africa. Microplastics were isolated from whole fish using a proteinase K digestion method, and then quantified and characterised in terms of shape, chemical nature (plastic type), colour and length. Fibres (68%) and fragments (21%) were the dominant shapes found. Of the 174 fish sampled, 52% contained microplastic particles, with 0.79 ± 1.00 particles per fish. The average number of particles per fish did not differ significantly across species within sites and across sites but was higher than in juvenile fish of other species sampled in oceanic habitats. The main plastic types collected using 10 mm filters and identified with Fourier Transform Infrared Spectroscopy (FTIR), were rayon (70.4%), polyester (10.4%), nylon (5.2%) and polyvinylchloride (3.0%). Particle length ranged from 0.1 to 4.8 mm, averaging 0.89 ± 0.77 mm, but irrespective of length, particles were mostly blue in colour. This study provides evidence that juvenile fish inhabiting mangroves are consuming significant quan- tities of microplastics. Importantly, it should be noted that rayon, though the most abundant plastic type found, is a semi-synthetic fibre made from regenerated cellulose that is commonly reported in studies of this nature. The habitats studied serve as nurseries for numerous fish species; however, more detailed studies are needed to assess whether microplastic ingestion could compromise the health of these fish or whether these effects are dependent on species, feeding habit and/or plastic type.