Determination and comparison of vitamin C, calcium and potassium in four selected conventionally and organically grown fruits and vegetables

It is evident that the growing interest in organically grown produce has correspondingly necessitated the debate on the nutritional supremacy between organically and conventionally grown produce. A study was carried out to determine and compare vitamin C, calcium and potassium in organically and conventionally grown cabbage, carrots, Cos lettuce and Valencia oranges. Samples were purchased from local supermarkets within Central Coast, New South Wales in Australia from late March to early April 2007. Vitamin C content was determined by 2,6-dichloroindophenol titrimetric method while calcium and potassium were determined by atomic absorption spectroscopy. Results from the study showed inconsistent pattern with respect to vitamin C, calcium and potassium contents in the conventionally and organically grown samples. No significant differences were observed in vitamin C content in conventionally and organically grown cabbage, carrots and Cos lettuce while significant differences were observed in Valencia oranges which showed higher vitamin C content in organic Valencia oranges as compared to conventional ones (51.8 to 43.4 mg/100 g fresh weight). Results on calcium and potassium contents showed significant differences in all the samples with the trend of higher values for organically grown cabbage, carrots and Cos lettuce as opposed to their conventionally grown counterparts. However, for Valencia oranges, results showed that the calcium and potassium contents were significantly higher in conventional Valencia oranges compared to the organic Valencia orange (54.5 and192.0 mg to 51.8 and 189.5 mg/100 g, respectively)

Incidence and distribution of Sweetpotato viruses and their implication on sweetpotato seed system in Malawi

A survey was carried out in 19 districts to investigate the prevalence and distribution of sweetpotato virus disease (SPVD) and its implication on the sustainability of clean seed system in Malawi. A total of 166 leaf samples were collected and tested for the presence of 8 viruses using nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA). SPVD foliar symptoms were observed in 68.42% of the surveyed districts. There were significant variations in disease incidence and severity (p < 0.001) among districts, with the highest incidence in Mulanje (28.34%). Average SPVD severity score was 3.05. NCM-ELISA detected sweet potato feathery mottle virus (SPFMV, 30.54%), sweet potato mild mottle virus (SPMMV, 31.14%), sweet potato mild speckling virus (SPMSV, 16.17%), sweet potato C-6 virus (SPC6V, 13.77%), sweet potato chlorotic stunt virus (SPCSV, 22.16%), sweet potato collusive virus (SPCV, 30.54%), sweet potato virus G (SPVG, 11.38%), cucumber mosaic virus (CMV, 7.78%) either in single or mixed infections. Data from this study indicate a significant SPVD occurrence in the country, and the consequence implications towards national sweetpotato seed system

Malawi potato variety catalogue 2021

This catalogue is the first for potato varieties registered in Malawi with the Agricultural Technology Clearing Committee (ATCC) of the Department of Agricultural Research Services (DARS) under the Ministry of Agriculture. The catalogue describes potato varieties in terms of use, tuber features, maturity period, yields, and resistance to diseases. A brief description of the growth characteristics has also been provided for each variety. Using the details provided, it is easy to identify each variety to target specific markets. This initiative is aimed at enhancing awareness about the released varieties and helping create the links between seed growers and potato farmers. This catalogue is, therefore, an important reference material for farmers and other market actors