Qualitative and Quantitative Improvement of Gerbera (Gerbera jamesonii) Cut Flowers by Nitrogen Forms Ratio Adjustment in Soilless Culture Nutrient Solution

This experiment was performed to evaluate the effect of different nitrogen forms (ammonium to nitrate ratio) on the growth and flowering characteristics of two gerbera cultivars (‘Stanza’ and ‘Double Dutch’). The aim was to recommend the appropriate amount of NH4+:NO3¯ ratio in the nutrient solution to optimize quantity and quality characteristics in gerbera. This experiment was conducted in a completely randomized factorial design with two factors including NH4+:NO3¯ ratios and cultivar type with three replications. The NH4+:NO3¯ ratios (0:100, 20:80, 40:60, and 60:40) were supplied as a first factor and second factor was gerbera cultivars (‘Stanza’ and ‘Double Dutch’). The results indicated that increasing ammonium concentration in the nutrient solution to more than 40% of total N, significantly reduced growth indices and gerbera flower numbers compared to NH4+:NO3¯ ratio of 20 to 80. Results showed that the highest flower number (314 flowers m-2 year-1), stalk dry weight (5.2 g), flower stalk diameter (0.92 cm), flower stalk weight (2.31 Kg) and vase life (14 days) were obtained in 80:20 of NH4+:NO3¯ ratio. Thereofre, nutrient solution with NH4+:NO3¯ ratio of 20:80 is an appropriate solution recommended for commercial production of gerbera cut flowers in order to achieve the optimum quantity and quality yield of Cut Gerbera.