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

Additional index words. ammonium, cut-fl ower, nitrate, nitrogen Abstract. The form of N supplied to the plant (NH 4 + or NO 3 - ) affects growth, morphology and a range of physiological processes in the plant. Little information is available concern- ing the effects of N form on development, production or quality of cut-fl owers. The present study investigated for the fi rst time the effects of N form and quantity on growth, fl ower production and fl ower quality of Ranunculus asiaticus L. The plants were cultivated in an inert mineral soilless medium (perlite) and were exposed to two levels of nitrogen fertiliza- tion (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 fl ower yield production, resulting in higher numbers of total fl ower produced as well as higher numbers of long fl owers. The results demonstrate an effect of N ferlilization treatments on cut-fl ower quality. Flowers grown under 50 ppm N application characterized by almost double vase life duration com- pared to fl owers grown under the various 100 ppm N treatments. However, fl ower quantity and quality were not affected by the level of NH 4 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 fl ower quality were apparent already under 100 ppm N supply.