Salinity Tolerance of Three Commonly Planted Narcissus Cultivars

Abstract

Salinity is a problem for crop production worldwide and may be particularly problematic for ornamental plants because it has the potential to degrade visual quality. Daffodils [Narcissus sp. (L.) Amaryllidaceae] are a popular bulb plant, in demand for both landscapes and cut flowers. In this study, we examined how salinities ranging from 0 to 300 mm NaCl affected growth, flower production, and leaf physiology of three of the most popular cultivars of daffodil (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’). Salinity reduced growth rate and biomass production at salinities greater than or equal to 100 mm NaCl with the greatest reductions in the highest salinity treatments (200 and 300 mm NaCl). Despite reductions in biomass, there was no significant chlorosis of the leaves. Flower quantity was unaffected by salinity in ‘Dutch Master’ and ‘Ice Follies’, but anthesis was delayed and flower duration was reduced by 40% to 70% at salinities of 150 mm NaCl and above. Anthesis and flower duration in ‘Tete-a-Tete’ were unaffected by salinity, but the number of flowers produced was negatively affected (reductions of 50% or more) by salinities of 150 mm NaCl and above. Sodium concentration in the leaves and bulbs increased 53% to 400% compared with the 0 mm NaCl control with lower accumulation in the bulbs than in the shoots. Sodium accumulation occurred at or above 50 mm NaCl in ‘Tete-a-Tete’, but at salinities greater than 150 mm NaCl in ‘Dutch Master’ and only in the 300-mm NaCl treatment in ‘Ice Follies’. Despite the Na+ accumulation in the leaves, the plants in most of the salinity treatments were able to maintain a K+:Na+ ratio above 1 (except in ‘Tete-a-Tete’ at salinities 150 mm NaCl or greater), which may have helped the daffodils tolerate the negative affects of Na+ and maintain good visual quality. ‘Dutch Master’, ‘Tete-a-Tete’, and ‘Ice Follies’ can be considered highly salt-tolerant because they maintain visual quality (leaf greenness, flower production, and flower duration) at soil NaCl-induced electrical conductivities greater than 6 dS·m−1.