Abstract
Abstract Nitrogen (N) forms and N levels can have a great impact on growth and quality of agricultural crops. Postharvest N treatments may also affect the quality of products. This study was conducted under laboratory conditions to evaluate the changes in postharvest quality characteristics of cut roses (Rosa hybrid cv ‘Utopia’) under different nitrogen concentrations of holding solution. Three nitrogen sources including ammonium sulfate, calcium nitrate and potassium nitrate at five concentrations (0, 5, 10, 15 and 20 mgL-1 N) were applied into vases with holding solution. The results showed that low ammonium (5 mg L-1) and high nitrate (20 mgL-1) resulted in the highest leaf SPAD values, whereas the lowest values were recorded for those stems treated with the two highest ammonium concentrations (15 and 20 mg L-1). Leaf and petal relative water contents (RWC) were significantly reduced by higher ammonium concentrations, while they were increased by increasing calcium nitrate and potassium nitrate concentrations in the vase holding solution. Leaf catalase activity was increased by the two lowest (5 and 10 mg L-1) and decreased by the two highest ammonium levels (15 and 20 mg L-1), and it was not affected by the two other nitrogen salts. Higher ammonium levels resulted in a significant increase in leaf proline concentrations and petal ion leakage, whereas nitrate concentrations reduced these two traits. A low concentration of ammonium (5 mg L- 1) increased flower vase life while higher ammonium concentrations reduced the trait. There was also an increasing trend in flower vase life with higher concentrations of both nitrate salts. Therefore, low ammonium or high nitrate levels in vase holding solution can improve vase life quality of cut roses.
Highlights
Roses are among the most important ornamental plants used as potted and cut flowers, as well as in decoration of urban landscapes
It has been shown that higher carbohydrate levels of plant tissues or postharvest application of sucrose can improve the vase life of cut flowers in many ornamental plants (Doi and Reid 1995; Ichimura et al 2003)
The results showed that when different concentrations of nitrogen from various sources were applied in holding solution, the physiological quality traits of cut rose stems showed different responses (Table 1)
Summary
Roses are among the most important ornamental plants used as potted and cut flowers, as well as in decoration of urban landscapes. Various cultivation strategies and postharvest treatments have been proposed to improve the quality of cut flowers (Ichimura et al 2003; Ahmadi et al 2009). Nutrient elements such as N, K, Ca, and their availability to plant roots can significantly improve the quality and vase life of cut roses (Roude et al 1991; Starkey and Pedersen 1997; Druge 2000; Zamani et al 2011). While in practice there is no negative effects of extra calcium and potassium concentrations on plant growth and quality; application of nitrogen more than plant’s need, could negatively influence many
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