Effect of different gibberllic acid and humic acid concentrations on growth and development characteristics of gladiolus (Gladiolus grandiflorus L. cv. White Prosperty)

Gladiolus is one of the bulbous cut flower with a variation in color, shape and size. Spike length, number of florets per spike, plant height and flowering time are the parameters that determine the quality of this flower. This study was carried out to evaluate the effect of gibberellic acid (0, 50, 100 and 150 ppm) and humic acid (0, 250 and 500 ppm) on quantitative and qualitative characteristics of Gladiolus grandiflorus L. cv. White prosperty. The experiment was laid out in a factorial arrangement based on randomized complete block design with two factors; gibberellic acid and humic acid, with 3 replications. Results showed that application of gibberellic acid at all used concentrations significantly increased plant height, inflorescence length and number of florets per inflorescence, compared to the control as well as reduced the time of flowering. Also, gibberellic acid at 50 ppm increased the number of cormlet per plant, and at 100 and 150 ppm enhanced the number of leaves, corm weight and chlorophyll index. Humic acid had no significant effect on flowering time, while significantly increased plant height, inflorescence length, number of cormlet per plant and cormlet weight at both used concentrations and number of leaves, number of florets per inflorescence and leaf chlorophyll index at 500 ppm compared to control.Finally, application of 100 ppm gibberellic acid and 500 ppm humic acid are suggested to improve growth and inflorescence quality in Gladiolus cv. White prosperty, respectively.