Effects of sulphur preservative on phytochemical and antioxidant capacity of peels of mango cultivars (Mangifera indica L.) produced in South Africa

Fruits have abundant phytochemicals that contribute as bioactive molecules with ability to lower incidence of diseases. Mangoes are rich in polyphenols and antioxidants. In this study, peels of six selected mango cultivars (Tommy Atkins, Peach, Saber, Sunshine, Keitt and Vhavenda) were treated with sulphur dioxide solutions (0, 10, 20, 50, 100, 150, 200, 250 and 300 ppm) as preservative of phytochemicals and antioxidants capacity. Regardless of cultivar, sulphur concentration had effect on composition of polyphenols and antioxidant capacity of mango peels, reaching a plateau at 50 ppm. Vhavenda cultivar has significantly highest polyphenols and antioxidant capacity than the other cultivars evaluated. This study reveals that mango peels are a prospective source of natural antioxidants as they constitute significantly higher total antioxidant capacity and phenolic content.Keywords: Antioxidants, mango cultivars, peels, phytochemicals, sulphur.African Journal of Biotechnology Vol. 12(41), pp. 6007-601

Proximate, chemical compositions and sulphur concentrations on quality of selected dried mango (Mangifera indica L.)

Preference for dried mango is on the increase as it provides a good source of nutrients, whilst evading consumption of fatty in some post-harvest processed fruits. However, data on proximate and chemical compositions of dried mango fruits is lacking. Hence this research was intended to determine effects of sulphur concentration (0, 10, 20, 50, 100, 150, 200, 250 and 300 ppm) on the nutritional value and the proximate composition of six selected mango cultivars (Tommy Atkins, Peach, Saber, Sunshine, Keitt and Vhavenda) grown in South Africa. The study shows that increasing sulphur concentration had a quadratic effect on mango pulp proximate concentration and chemical composition, reaching a maximum at 50 ppm regardless of cultivar. Significant differences (p<0.01) in nutrient content were found in the mango cultivars. Keitt had significantly more protein than other cultivars, whilst Vhavenda had more fibre contents. Significant differences (p<0.01) in secondary metabolites were also found in the mango cultivars with Saber having significantly more polyphenols (0.4 mg of Gallic acid/100 mg) and antioxidants (65.4 μmol/g).Keywords: Mango cultivars, nutritional value, proximate composition, sulphurAfrican Journal of Biotechnology Vol. 12(19), pp. 2678-268

Different nursery growing systems and growth media improved germination and seedling growth of fever tea (Lippia javanica)

An experiment was set up in a Completely Randomized Design (CRD) to examine the influence of nursery growing methods and growth medium on fever, tea germination, and seedling development. Two nursery growth methods (Conventional-CON and Float tray system FTs) and six different growing medium (pine bark, peat moss, coco peat, vermiculite, sand, and cattle manure) were used. ANOVA was used to compare treatment means, and means were separated using the Least Significant Difference (LSD) at a 5 % significance level. The nursery growing method and growth material exhibited a strong interaction regarding the germination index, germination percentage, seedling height, leaf area, root length, density, and final crop stand. The float tray approach yielded the greatest germination index for peat moss and the lowest for cattle manure. In the float tray method, peat moss and coco peat had the highest germination percentages, whereas cattle manure had the lowest. Under the float tray technique, the tallest seedlings emerged in peat moss and the smallest in coco peat. Peat moss had the most leaf area in the float tray system, whereas coco peat had the least in the conventional technique. Peat moss in the float tray system had the highest root length density while coco peat in the conventional technique had the lowest. Peat moss in the float tray system had the highest final crop stand, whereas seedlings in the conventional and float tray systems had nothing. based on the findings, it is recommended that fever tea seedlings be grown on peat moss using the float tray metho

Hydropriming improves seed germination in horned melon (Cucumis metuliferus E. Mey. Ex Naudin) landraces

The global popularity of horned melon highlights the need of sound crop establishment processes, since uniform and quick seed germination has a substantial influence on crop yield and quality. Using a Completely Randomised Design (CRD) with a factorial structure, the effects of hydro priming durations (0, 8, 16, 24, 32, and 40 h) on seeds of two horned melon landrace (L1&L2) were investigated. Hydro priming had significant (P>0.05) influence on several germination indices (germination percentage, relativized percentage, mean germination rate, germination index, synchronization, duration to 50 % germination, mean daily germination, peak value, and germination value). Among the germination indicators tested, landrace (L2) exhibited a considerably stronger germination response than L1. The findings also reveal a curvilinear relationship between priming length and germination percentage, with 24 hours being greatest proportionately. The mean germination rate, germination index, mean daily germination, peak value of germination, and germination value all rose as the hydro priming duration increased. Primed seeds germinated more quickly than unprimed ones. With increasing priming duration, the synchronization index fell linearly. The interaction between landraces and hydro priming was not significant (P>0.05) for final seed germinated, relativized germination, and synchronization indices, but it had a significant impact on all other indices. Because the efficacy of hydro priming tends to lessen with extended soaking, we recommend using it for a maximum of 32 hours. Future study should concentrate on alternative priming chemicals and the applicability of various priming solutions for various agroecosystem

Priming seeds with potassium nitrate is associated with modulation of seed germination and seedling growth ecology of cucumis metuliferus

The horned melon (Cucumis metuliferus) is mostly grown in tropical and subtropical countries, where it thrives on deep to shallow, well-drained soils. Seed dormancy, which causes poor and delayed germination, has remained a problem for farmers in several African countries, including Zimbabwe, who have begun producing horned melon. Midlands State University conducted a laboratory experiment to evaluate the effects of potassium nitrate on seed germination and early seedling growth of horned melon. The experiment was set up in a Completely Random Design (CRD) with seven different potassium nitrate (KNO3) concentrations (0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, 2.5 %, and 3.0 %), each duplicated three times. The data was analyzed using a one-way Analysis of Variance (ANOVA) in Genstat 18th edition. The characteristics of germination and early seedling development were assessed. All germination and early seedling development characteristics were significantly affected by potassium nitrate. Germination %, mean germination rate, germination index, mean daily germination percent, synchronization of germination, peak value for germination, and germination value all had a significant influence. Potassium nitrate had a significant influence on mean germination time and time to 50 % germination, with the lowest values obtained on seeds primed with 3 % KNO3. There was a significant difference in seedling height, root length, seedling length, fresh biomass, and dry weight between seeds primed with 2.5 % KNO3 and seeds not primed with 2.5 % KNO3. Farmers are advised to use 2.5 % KNO3 concentration for seed priming for optimal germination and early plant development of horned melo

The effect of nitrogen and sulphur on the nutrient use efficiency, yield and quality of canola (Brassica napus L.) grown in the Western Cape

Thesis (PhD(Agric))--Stellenbosch University, 2012.ENGLISH ABSTRACT: There is an increasing demand for canola (Brassica napus L.), an emerging oilseed crop in South Africa. Canola thrives in the Western Cape. However, yet low yields are still obtained within the production areas with poor and or variable responses to nitrogen applications. Crop nutrition and specifically the contribution of sulphur (S) to nitrogen (N) use and selection of nutrient efficient genotypes can be strategies of considerable significance in increasing yields. This study investigated growth, yield and quality responses of canola to different N (0, 30, 60, 90 and 120 kg N ha-1) and S (0, 15 and 30 kg S ha-1) fertilisation rates in field trials at different localities, during the 2009-2011 period. Responses to N and S under optimum growing conditions and responses of different cultivars were investigated in unison in glasshouse trials at the Department of Agronomy of the University of Stellenbosch. Locality and growing season (year) significantly affected nutrient content in plants at flowering (90 days after planting), dry mass production as well as yield and quality of canola in field trials at five different localities during the 2009-2011 period. Growth and yield were also affected by N application rate in both field and glasshouse trials. Sulphur applications did not have an effect on vegetative growth, but rather stimulated flower and pod production in glasshouse trials and resulted in higher grain yields in field trials. Response depends largely on rainfall and S content of the soil. Highest yields were, on average, obtained with application rates of 120 kg N and 30 kg S ha-1, while glasshouse trials showed that even higher rates may be considered under optimum growing conditions. High application rates of N and S also improved water use efficiency from approximately 4-5 kg grain yield to about 8-9 kg grain yield mm-1 of rain during the growing season. Agronomic efficiencies of applied N decreases with increasing N rates and values of about 8 kg grain yield increase per kg of N applied at N rates of 120 kg N ha-1 indicated that high N rates may improve profit margins of canola as long as the cost of N is not more than eight times the producers price of canola. Agronomic efficiencies of N applications are improved if 15 kg S ha-1 is applied complimented with high rainfall, but not with applications of 30 kg S ha-1. Improved agronomic efficiencies of S applications shown at higher N rates, confirmed the dependency of S responses to sufficient availability of nitrogen. Sulphur applications, in contrast to N, resulted in an increase in oil content of the grain in field trials. Yield responses of different cultivars to nitrogen fertilisation under glasshouse conditions differed, with better responses obtained within short and medium season cultivars, than with a late maturing (long season cultivar), in spite of a better vegetative (dry mass) response of the later maturing cultivar. These results may indicate differences in the growth habit of different cultivars, but more research in this regard is needed.AFRIKAANSE OPSOMMING: Canola (Brassica napus L.), ‘n relatief nuwe oilsaadgewas wat goed aangepas is, word in ‘n toenemende mate in die produksiegebiede van die Weskaap verbou. Lae opbrengste en wisselvallige reaksies teenoor stikstofbemesting word egter verkry ten spyte van die gewas se hoë stikstofbehoefte en dit mag moontlik aan swaweltekorte toegeskryf word. In hierdie ondersoek is die groei-, opbrengs- en kwaliteitsreaksie van canola teenoor verskillende N (0, 30, 60, 90 en 120 kg N ha-1) en S (0, 15 en 30 kg S ha-1) bemestingspeile in droëland proewe op verskillende lokaliteite bestudeer gedurende die 2009-2011 groeiseisoene. Reaksies teenoor N en S onder optimale groeitoestande en vir verskillende cultivars is in glashuisproewe van die Departement Agronomie van die Universiteit van Stellenbosch, uitgevoer. Die chemiese samestelling van die plante tydens blomstadium (90 dae na plant), asook droëmateriaal produksie, graanopbrengs en kwaliteit het betekenisvol verskil tussen die lokaliteite, maar lokaliteitsverskille is ook deur die seisoene beïnvloed. Die ontwikkeling, groei en graanopbrengs van die canola is ook beïnvloed deur die stikstofbemestingspeile in beide die veld en glashuisproewe. Swawelbemesting het nie die vegetatiewe groei van canola beïnvloed nie, maar het blom en peulproduksie in glashuisproewe en graanopbrengste in veldproewe verhoog. Die reaksie van canola teenoor die swawelbemesting is grootliks bepaal deur die swawelinhoud van die grond asook klimaatsfaktore soos reënval. In die algemeen is die hoogste canola opbrengste in veldproewe met toedienings van 120 kg N en 30 kg S ha-1 verkry, maar glashuisproewe het getoon dat hoër toedieningspeile nodig mag wees onder optimale groeitoestande soos in besproeiingsgebiede. Hoë toedieningspeile van N en S het veroorsaak dat die waterverbruiksdoeltreffendheid toegeneem het van 4-5 kg graanopbrengs per mm reën tot sowat 8-9 kg graan opbrengs per mm reën. Agronomiese doeltreffendheid van toegediende stikstofbemesting het afgeneem met toenemende N peile, maar waardes van ongeveer 8 kg opbrengsverhoging per kilogram N toegedien met stikstofpeile van 120 kg ha-1, toon dat hoë N toedieningspeile mag steeds winsgrense verhoog mits die prys van een kilogram N nie meer is as agt maal die produsente prys van canola is nie. Agronomiese doeltreffendheid van stikstofbemesting is verhoog deur ook 15 kg S per hektaar toe te dien, maar nie deur die toediening van 30 kg S ha-1 nie. Die agronomiese doeltreffendheid van S toedienings het slegs by die gelyktydige toediening van hoë stikstoftoedienings toegeneem, wat die wisselwerking tussen N en S ten opsigte van graanopbrengs bevestig. In teenstelling met stikstof het swawel toedienings die olie-inhoud van canola in die veldproewe verhoog. In glashuisproewe is gevind dat kort en medium groeiseisoen cultivars, ten spyte van ‘n groter vegetatiewe reaksie van die lang groeiseisoen cultivars, groter opbrengsreaksies teenoor stikstof- en swawelbemesting toon. Meer navorsing word egter in hierdie verband benodig

Effect of gibberellic acid and potassium nitrate seed treatments on the emergence and seedling vigor of Amaranth and Cleome gynandra

Abstract Seed dormancy is the major challenge in the cultivation of Amaranth and Cleome gynandra. Amaranth and C. gynandra are affected by chemical, physical, and physiological dormancy. The current study was conducted at the Marondera University of Agricultural Sciences and Technology (MUAST) farm in 2021 and 2022. The effects of gibberellic acid and potassium nitrate seed treatments on the emergence and seedling vigour of Amaranth and C. gynandra were evaluated. Seeds of Amaranth and C. gynandra were pre‐soaked in gibberellic acid (control 0, 100, 200, 300,400, and 500 ppm) and potassium nitrate (control 0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) solutions for 24 h to have a factorial layout within a randomized complete block design replicated three times. Seeds of Amaranth and C. gynandra treated with gibberellic acid showed a significant difference while potassium nitrate showed no significant difference. The highest emergence percentage and vigor index were recorded in seeds treated with 500 ppm gibberellic acid. The maximum emergence percentages of Amaranth (62.1%) and C. gynandra (60.7%) were obtained in 2022 and 2021. The least emergence percentages of Amaranth (46.4%) and C. gynandra (45.3%) were obtained in control in 2021. The highest vigor index of Amaranth (603) was obtained in 2022, while the highest vigor index of C. gynandra (562) was obtained in 2021. The lowest vigor indices of Amaranth and C. gynandra were 341 and 270, which were recorded in 2021 and 2022. The results showed that gibberellic acid has the potential to reduce seed dormancy

Evaluating the Suitability of Baobab Fruit Shells as Substrate for Growing Oyster Mushroom (Pleurotus ostreatus)

The baobab fruit shells were evaluated for their suitability as a substrate for growing oyster mushrooms and compared to three base substrates (wheat straw, maize cobs, and sawdust) of 1 kg dry weight. The duration of developmental stages, mycelium vigor, yield, and biological efficiency of the oyster mushroom from the four different substrates were recorded. Yields from the first 3 harvests (flushes) were considered, as they were the most productive ones. Wheat straw demonstrated significantly (p<0.05) higher mycelial colonization rate taking an average of 23 days to complete full spawn run followed by baobab fruit shells, sawdust, and maize cobs which took averages of 25.8, 27.2, and 29.5 days, respectively. Baobab fruit shells had the longest number of days taken between full spawn run and first pinhead formation with an average of 14.4 days which was significantly different (p<0.05) to the wheat straw, sawdust, and maize cobs which had 7.4, 9.4, and 10.5 days. The highest yield was observed on the sawdust which had an average of 682 g followed by wheat straw with 594 g. Maize cobs and baobab fruit shells had the least yield of 518 g and 482 g, respectively. The results showed that baobab fruit shells could be used as a substrate for the cultivation of oyster mushrooms and it can be recommended for commercial cultivation of oyster mushrooms