Effects of Supplied Nitrogen Form and Quantity on Growth and Postharvest Quality of Ranunculus asiaticus Flowers

Abstract

<jats:p>The form of N supplied to the plant (NH<jats:sub>4</jats:sub><jats:sup>+</jats:sup> or NO<jats:sub>3</jats:sub><jats:sup>–</jats:sup>) affects growth, morphology and a range of physiological processes in the plant. Little information is available concerning the effects of N form on development, production or quality of cut-flowers. The present study investigated for the first time the effects of N form and quantity on growth, flower production and flower quality of <jats:italic>Ranunculus asiaticus</jats:italic> L. The plants were cultivated in an inert mineral soilless medium (perlite) and were exposed to two levels of nitrogen fertilization (50 or 100 ppm) and three levels of NH <jats:sup>+</jats:sup><jats:sub>4</jats:sub> (10%, 20%, or 30%, under 100 ppm nitrogen fertilization). Larger shoots and increased shoot/root ratios were obtained in the lowest (50 ppm) N treatment. This treatment also excelled in flower yield production, resulting in higher numbers of total flower produced as well as higher numbers of long flowers. The results demonstrate an effect of N ferlilization treatments on cut-flower quality. Flowers grown under 50 ppm N application characterized by almost double vase life duration compared to flowers grown under the various 100 ppm N treatments. However, flower quantity and quality were not affected by the level of NH<jats:sub>4</jats:sub> applied. The <jats:italic>R. asiaticus</jats:italic> L<jats:italic>.</jats:italic> root was less sensitive to the N fertilization treatments than its shoot. Contents of organic N, NO <jats:sup>–</jats:sup><jats:sub>3</jats:sub>, P, K, Ca, Mg, Na, Cl, Fe, Cu, Zn, B, and Mo in the leaves were not affected by the fertilization treatments. Taken together, our results suggest a low requirement of <jats:italic>R. asiaticus</jats:italic> L. for N fertilization, and insensitivity to ammonium concentrations in the range of 10 to 30 ppm, 10% to 30% of the total N supplied. Detrimental effects in terms of growth, production and cut flower quality were apparent already under 100 ppm N supply.</jats:p>

Development of “stem-topple” disorder inRanunculus asiaticusis related to localised disturbances in tissue calcium levels

“…Therefore, if the "stem-topple" disorder in R. asiaticus was related to impaired calcium nutrition, an elevated supply of NH 4 + may exacerbate the severity or extent of the disorder. Nevertheless, we reported that the extent of "stemtopple" in R. asiaticus was not correlated with the level of NH 4 + supplied to the plant (Bernstein et al, 2005). Moreover, the calcium concentrations in leaves from the N-fertilisation treatment that demonstrated significantly lower "stem-topple" damage, were not significantly different from leaves from all other treatments.…”

“…Although the overall calcium concentrations in leaves "Stem-topple" in Ranunculus of R. asiaticus were not affected by N-treatment (Bernstein et al, 2005), reduced concentrations of calcium might have been induced locally, in the region of the flower stem sensitive to bending. Such localised alterations in tissue calcium concentrations have been shown to occur in plants, and to affect growth or to induce physiological disorders (Bernstein et al, 1993;1995;Bar-Tal and Pressman, 1996;Ho and Adams, 1989).…”

“…The experiment was conducted in a naturally ventilated greenhouse as previously described (Bernstein et al, 2005). The Ranunculus cultivar used was 'White Friandin' and plants were grown in rows in perlite beds (40 cm wide ϫ 20 cm high).…”

“…To analyse Cl -and NO 3 -, dried plant samples were extracted with water, and Cl -was measured using a chloride meter (PCLM3; Jenway, Chelmsford, UK), and NO 3 -with RQFLEX (Ntest; Merck, Gibsstown, NJ, USA). To analyse K, Na, Ca, Mg, Fe, Zn, Mn, Cu, Mo and B, stem tissue was digested with 65% (v/v) HNO 3 and 70% (v/v) HClO 4 (Neves Piestun and Bernstein, 2005). K and Na were measured by flame photometry, Ca and Mg by atomic absorption spectrophotometry (Perkin Elmer 460; Perkin Elmer, Waltham, MA, USA), and micro-elements using a Spectroflame Modula ICP 61E Trace analyser (ThermoElectron Corp., Waltham, MA, USA).…”

“…In a previous publication, we reported the occurrence of "stem topple" in Ranunculus asiaticus L. (Bernstein et al, 2005). Approx.…”