Exponential Growth of Gladiolus ‘Glamini’ Under the Influence of Plant Growth Regulators

Gladiolus xhybridus is a perennial monocot in the Iridaceae. Gladiolus is top ten major cut flowers sold in the USA. In commercial production, gladioli corms produce 1-2 inflorescences per shoot, each of which produce multiple flowers. However, gladioli have the ability to generate multiple shoots, which could influence the flowering timing and floral traits of gladiolus in addition to cormel production. Our objectives are to analyze the influence of plant growth regulators (gibberellic acid 3, GA₃; 6-benzyadenin, BA) on the number of shoots, number of inflorescences/shoot, flower timing, plant and flower height, weight and number of corms and cormels produced. BA treatments significantly increased the generation of multiple shoots (vegetative, floral): 6.0 vs. 1.2 (BA vs. control and GA₃, respectively). Also in week 7, GA₃ and the control treatments resulted in significantly taller vegetative shoots than BA. However, in week 13 and beyond the BA treatment overcame this foliage height difference. BA treatments utilized the energy in gladiolus corms to enhance the generation of stalks as a tradeoff of foliage height; yet over time the multiple vegetative shoots were able to support the energy demands, resulting in an exponential growth pattern.