The form of N supplied to the plant (NH4+ or NO3–) 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 Ranunculus asiaticus 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 +4 (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 NH4 applied. The R. asiaticus L. root was less sensitive to the N fertilization treatments than its shoot. Contents of organic N, NO –3, 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 R. asiaticus 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.
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