School of Agriculture & Life Sciences

The influence of exogenously applied 2,4-dichlorophenoxyacetic acid on fruit drop and quality of navel oranges (Citrus sinensis L.)

Mon, 18 May 2009 00:00:00 GMT

The influence of exogenously applied 2,4-dichlorophenoxyacetic acid on fruit drop and quality of navel oranges (Citrus sinensis L.) Modise, D.M.; Likuku, A.S; Thuma, M.; Phuti, R. Orchard experiments were carried out in Botswana with the objective of evaluating the effect of 2,4- dichlorophenoxyacetic acid (2,4-D) on reducing premature fruit drop. Different concentration levels of the 2,4-D (8, 16 and 20 mg/L were applied exogenously to mature fruit trees of sweet orange (Citrus sinensis L.) in the 2004/2005 season. In the 2005/2006 season the 2,4-D treatments ranged from 20 to 40 mg/L concentration. There appeared a general increase in fruit drop for the month of October in all treatments but a decrease in fruit drop was observed in the fruit trees with 16 and 20 mg/L 2,4-D concentration, that is, from November through February; with the latter showing the least number of fruits that dropped throughout the execution of the experiments. The application of 20 mg/L 2,4-D significantly reduced fruit drop by more than 50% but higher concentration levels of the plant growth regulator significantly increased fruit drop. It was also evident that, small sized fruits were more susceptible to fruit drop than larger fruits. These findings suggested that, 2,4-D can be an effective tool to control fruit drop by enhancing retention, as well as improving the quality of navel oranges under dry climatic conditions

Determination of aflatoxins in peanut (Arachis hypogaea L.) collected from Kinshasa, Democratic Republic of Congo and Pretoria, South Africa : a comparative study

Tue, 16 Apr 2013 00:00:00 GMT

Determination of aflatoxins in peanut (Arachis hypogaea L.) collected from Kinshasa, Democratic Republic of Congo and Pretoria, South Africa : a comparative study Kamika, Ilunga This study assessed the mycological and aflatoxin contamination of peanuts collected from Kinshasa, DRC and Pretoria, South Africa. Forty peanut samples were collected randomly at informal markets in the two cities and analysed for mycoflora and aflatoxins (B1, B2, G1 and G2) using standard methods. The results indicated that 95% and 100% of peanut samples collected from Kinshasa and Pretoria, respectively were contaminated with aflatoxigenic fungi with Kinshasa’s samples being the most contaminated (up to 49, 000 CFU/g). Seventy percent (70 %) of Kinshasa-samples and 35% of Pretoria-samples exceeded the maximum allowable limit of aflatoxin B1 set by JECFA (5 ppb). Statistical evidence showed a significant positive correlation between mycoflora and aflatoxin level for Kinshasa-samples (r = 0.4743, p < 0.005) while Pretoria-samples showed no correlation. The study reveals that high level of contamination in Kinshasa-samples could be due to the tropical nature of the climate and poor storage conditions as compared to Pretoria which is sub-tropical and sanitary regulations are enforced.

A phytochemical and biological investigation of Sutherlandia Frutescens

Tue, 01 Nov 2011 00:00:00 GMT

A phytochemical and biological investigation of Sutherlandia Frutescens Faleschini, Maria Teresa Since ancient times, indigenous plants have been used by traditional healers for treating various ailments. Sutherlandia frutescens is one of the most commonly used medicinal plants of southern Africa. This widely distributed plant has been traditionally used to treat cancer and HIV patients; however scientific validation is still in high demand. This research aimed to phytochemically characterise the various extracts prepared and to determine if any chemotypes were present. Subsequent biological characterisation was carried out to preliminary ascertain whether this medicinal plant could have anti-cancer and/or immunemodulating properties and which compounds might be responsible for these actions. Various traditional and organic extracts were prepared. Extracts, fractions and compounds generated were analysed and chemical profiles obtained. Column chromatographic techniques were used to isolate and purify compounds and structure elucidation was carried out using various analytical techniques. Sulforhodamine B and cytometric bead array assays were performed to determine the biological activities of samples generated.

Market segmentation and consumer willingness to pay for high fibre products : the case of Johannesburg and the surrounding areas, South Africa

Thu, 01 Sep 2011 00:00:00 GMT

Market segmentation and consumer willingness to pay for high fibre products : the case of Johannesburg and the surrounding areas, South Africa Chabikuli, Nsengiyumva Functional foods constitute a growing focus for research, product development and consumer interest in recent years. This study investigated the factors that affect willingness to pay for high fibre food on the market as well as respondents’ attitude towards the purchase of these products. The results indicated that those consumers in the high income group were more health conscious than their low income counterparts and willing to pay for high fibre products. The results showed that health risk perceptions as well as regulatory programmes affected consumers’ willingness to pay. The results also showed that at low percentage prices consumers were willing to pay for high fibre products. Gender and marital status did not seem to have an influence on willingness to buy for any of the selected products. Findings of the study could encourage food manufacturers to carry on with developments of functional foods since willingness to pay increased with increase in income.