Abstract
Taro (Colocasia esculenta (L.) Schott) is a staple food crop in the Asia-Pacific region in areas where rising sea levels are threatening agricultural production. However, little is known about its response to salinity. In this study, we investigated the effects of salinity on the growth, morphology, physiology, and chemical traits of taro to predict the impacts of rising sea levels on taro production and nutritional value in the Pacific. We grew taro (approximately 4 months old) with a range of NaCl treatments (0–200 mM) for 12 weeks. Full nutrient, micronutrient, and secondary metabolite analyses were conducted, including measures of calcium oxalate (CaOx), an irritant that reduces palatability. Significant reductions in growth and biomass were observed at and above 100 mM NaCl. Concentrations of macro- and micronutrients, including sodium, were higher on a per mass basis in corms of plants experiencing salt stress. Foliar sodium concentrations remained stable, indicating that taro may utilize a salt exclusion mechanism. There was a large amount of individual variation in the concentrations of oxalate and phenolics, but overall, the concentrations were similar in the plants grown with different levels of salt. The total contents of CaOx and phenolics decreased in plants experiencing salt stress. Taro’s ability to survive and produce corms when watered with a 200 mM NaCl solution places it among the salt-tolerant non-halophytes. The nutritional quality of the crop is only marginally affected by salt stress. Taro is, therefore, likely to remain a useful staple in the Pacific region in the future.
Highlights
Rising sea levels pose a major challenge for the food security and livelihood of communities around the world, in low-lying regions, such as the Pacific [1,2]
With sea levels in the Pacific rising by as much as 10 mm each year [2], it is important to assess the tolerance of major crop plants in the region to salinity in order to prepare for the future
Corm mass was significantly reduced across salt treatments, with a 38–43% reduction in the mean corm mass in plants in the 200 mM NaCl treatment group compared to the control (Table 1, Figure 2b)
Summary
Rising sea levels pose a major challenge for the food security and livelihood of communities around the world, in low-lying regions, such as the Pacific [1,2]. With sea levels in the Pacific rising by as much as 10 mm each year [2], it is important to assess the tolerance of major crop plants in the region to salinity in order to prepare for the future. Root and tuber crops are important staples throughout the world. This is true in the Pacific Islands, where, aside from bananas and breadfruit, the main staples are yams, taro, cassava, and sweet potato [5]. Despite its regional importance, taro is a neglected crop, and little is known about taro physiology or how it responds to environmental stresses of any kind [11,13]
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