Sodium Chloride Concentration Affects Early Growth and Nutrient Accumulation in Taro

Abstract

The growth and nutrient accumulation responses of taro [Colocasia esculenta (L.) Schott, cv. Bun long] to varying sodium chloride concentrations were studied in an aerated hydroponic system. Vegetative propagules were grown at seven levels of NaCl (0, 5, 10, 20, 40, 60, and 80 mm) for 43 days. We estimated the NaCl tolerance threshold (95% of maximum growth) to be at 4.9 mm solution NaCl. Relative dry-matter yield decreased 1.6% per mm increase in solution NaCl above 4.9. These values for tolerance threshold and response slope led us to classify this taro cultivar as sensitive to salinity. As solution NaCl levels increased, Na concentration in petiole and root tissues increased, but not in lamina (leaf blade) tissues. This implies the existence of an effective mechanism for excluding excess Na, in spite of a lack of tolerance to solution NaCl in terms of growth response. Chloride concentration increased in all plant tissues with increasing solution NaCl levels; the greatest increase occurred in petiole tissue, and the lowest in lamina tissue, indicating some ability to partition Cl levels within the plant. Tissue concentrations of Ca and Mg, but not of K, were reduced by high solution NaCl levels.