the effect of different concentrations of gibberellic acid on quantitative and qualitative characteristics of three cultivars lacourtine, yokohama and red favourite tulip (tulipa gesneriana l.)

tulip is one of the most important flowers to precocity. treatment of tulip bulbs with gibberellic acid reduces the forcing period in the greenhouse resulting energy saving and reduces the tulip’s physiological disorders. this study carried out about three tulip cultivars includes ‘lacourtine’, ‘yokohama’ and ‘red favourite’. the results showed that gibberellic acid reduced significantly stem length, first internode length and duration of precocity period. based on the results gibberellic acid at 250 and 500 ppm can be effective agent in tulip’s precocity.