Sweet Potato Cultivar with Characteristic Acid-Green Foliage as an Alternative Leafy Vegetable to Water Spinach Grown in Polluted Habitats

Abstract

Water spinach (WS) is a leafy vegetable that accumulates toxic elements when grown in polluted habitats. Unfortunately, WS sold in the Sri Lankan local market, mainly comes from polluted sites. The fast-growing cultivar, acid-green sweet potato (AGSP), is an underutilized leafy vegetable in Sri Lanka. In this study, the applicability of AGSP shoot-tops to replace WS was assessed. WS samples were collected from an urban wastewater channel (WS-UWC), open market (WS-C), and AGSP leaves from a farming site to conduct elemental analysis using Inductive Coupled Plasma Mass Spectrometric (ICP-MS) method. The growth of WS and AGSP under standard growing conditions on soil beds were also compared. Greenhouse-grown WS and AGSP shoot-tops were prepared as dishes under three recipes and subjected to sensory evaluation. The phytochemical contents of WS and AGSP were also compared. Finally, DNA fingerprinting assay with trnH-psbA locus was performed to check the presence of WS in culinary preparations made with AGSP. The WS-C and WS-UWC contained significantly higher amounts of toxic heavy metals compared to AGSP. The toxic element Pb was detected only in WS-UWC. When considering growth, AGSP shoot-tops were grown faster and higher yield was given than WS. Consumers prefer WS over basic stir-fried AGSP with minimum flavours. However, consumers accepted AGSP when flavors and chicken cubes were added to the recipe, as if it was WS. The nutritional value of AGSP was higher than WS. The trnH-psbA could be used to detect the presence of WS/AGSP as an adulterant/ingredient in culinary dishes. Thus, AGSP can be proposed as a safer and healthier alternative to WS that is prone to bioaccumulation