Effects of gibberellic acid and humic acid on some growth characters of Daffodil (Narcissus jonquilla cv. German)

In order to evaluate the effect of gibberellic acid and humic acid on some morphological and physiological traits of Narcissus cv. German, a factorial experiment was conducted in a completely randomized design with 2 factors, 12 treatments, 3 replications and 5 pots in each plot. The first factor was gibberellic acid at four levels with concentrations of zero (control), 150, 300 and 450 ppm which was carried out by immersing onions in the mentioned concentrations of gibberellic acid for 48 hours. The second factor was humic acid at three levels with concentrations of zero (control), 250 and 500 ppm which was carried out as a foliar application at the vegetative stage. Analysis of variance showed that the effects of gibberellic acid treatment on appearance of flowering stem, flowering time and flower diameter had a significant effect compared to control. Gibberellic acid and humic acid treatments had individually significant effects on total chlorophyll, carotenoid and diameter of narcissus bulbs. The most leaf area was also related to the interaction of gibberellic acid (300 ppm) and humic acid (500 ppm). In general, results of this study indicated that according to the studied traits, use of gibberellic acid (300 ppm) and humic acid (500 ppm) was the best treatments to improve the studied traits.