Nutritional quality of amadumbe (Colocasia esculenta L. Schott) and development of an efficient tissue culture propagation protocol

Abstract

Colocasia esculenta (L.) Schott commonly known as amadumbe in South Africa is a conventional underutilised crop. Nutritionally, amadumbe leaves and corms contain nutritionally rich micro- and macro minerals. Amadumbe also contains high fibre, carbohydrates, and protein reserves. Amadumbe can be used as a dual-purpose crop to satisfy undernourished individuals and to alleviate global food insecurity. This research aimed to investigate the quality of amadumbe for use as a green leafy vegetable and to optimize a decontamination procedure to eliminate surface and endogenous contaminants in explants for plant tissue culture. Two sites Umbumbulu (South) and Snembe (North) of KwaZulu-Natal, South Africa were sampled and studied. The two sites are located on opposite ends of the province experiencing varied weather patterns viz. temperature and precipitation. Umbumbulu experiences temperatures of 26.2±20.6°C with annual precipitation of 573 mm compared to Snembe with temperatures of 26.5±20.2°C and annual precipitation of 597 mm. Specifically, the (young and mature) leaves and corms were harvested and processed for the quantification of the nutritional (micro and macro nutrients), proximate composition (organic molecules), antinutritional (oxalate concentrations) and optimisation of plant tissue culture decontamination procedure. Furthermore, soil samples were collected from both sites for determination of the soil mineral composition. Potassium was the dominant macro element ranging from (2.0 – 5.1 g/100 g), calcium (0.08 – 1.5 g/100 g), magnesium (0.14 – 0.48 g/100 g), and phosphorus (0.14 – 0.43 g/100 g) in plant tissues. Furthermore, higher levels of micro nutrients were observed with iron (13.4 -88 mg/100 g) and manganese (2.2 – 64 mg/100 g) dominating. Amadumbe leaves also showed to be abundant in moisture, protein, ash, NDF, and ADF. The soil mineral concentrations were significantly different (p<0.05) between locations with soil:plant organ interaction. The effect of [Control, PPMTM, PPMTM (P), NaDCC, and NaDCC (P)] in eliminating contaminants was insignificant (p>0.05), and further optimization approaches need to be investigated. Benlate, alcohol, and TWEEN 20 did not provide any effective outcome to remove possible endogenous and surface contaminants. Bacterial (BC), fungal (FC), and aseptic (ACS) cultures were lost at 120 d due to obstinate microorganisms.