Narcissus Cultivar Differences in Response to Saline Irrigation When Application Began Either Pre- or Postemergence

Abstract

Salinity affects crop production worldwide and can be particularly problematic for ornamental plants. Daffodils (Narcissus sp. L.) are one of the most popular bulb plants, in demand for both landscapes and cut flowers. In this study we examined how moderate salinity, imposed as NaCl, affected growth, flower production, and leaf physiology when salinity treatment began either pre- or postemergence. Salinity did not affect growth rate or flower production for the three early-season cultivars (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’) regardless of when salinity treatment began, but there were reductions in dry shoot biomass production under the highest salinity (50 mm NaCl). The mid-/late-season cultivar (‘Actaea’) had growth reduction and decreased flower production at the highest salinity when salinity treatment began preemergence. Within 28 days of greenhouse growth, the plants in the 50 mm NaCl treatment had carbon assimilation rates of only 25% to 32% of the 0 mm NaCl control. Sodium concentration increased 35% to 900% in the leaves in response to salinity for all cultivars when salinity treatment began preemergence but significantly increased only for ‘Actaea’ and ‘Tete-a-Tete’ (42% to 235%) when salinity treatment began postemergence. Potassium concentration in the shoot was mostly stable in response to salinity. The ability to maintain potassium (K) content within the plant may help daffodils tolerate the negative effects of sodium (Na). We believe that ‘Actaea’ was more negatively affected by salinity than the other three cultivars because, as a mid-/late-season cultivar, it had a much longer exposure period to salinity than the three early-season cultivars. However, moderate salinity does not seem to have a significant impact on growth and visual quality for ‘Dutch Master’, ‘Ice Follies’, or ‘Tete-a-Tete’ indicating that at least some saline water can be used for plant production without losses in plant quality.