Effects of Nitrogen Rate and Planting Time on Vegetative Traits and Corm Yield of Gladiolus (Gladiolus grandiflora L. cv. Oscar)

In order to study the effects of nitrogen and planting time on vegetative traits and yield of Gladiolus (Gladiolus grandiflorus cv. Oscar) corms, an experiment was conducted as a factorial design in the base of RCBD with 3 replications in Horticultural Research Farm, College of Agriculture, Karaj. First factor was 3 nitrogen levels (10, 20 and 30 gm-2). As urea fertilizer and second factor was 3 planting times (May 13, May 23 and June 3, 2003). Results showed that in the first planting time, tallest plants and highest corm yield (dry weight percentage, fresh weight mean, corm diameter and number of cormlets) were obtained. In the second planting time, the highest amount of flower fresh weight was obtained. Planting time had no significant effect on some traits like leaf numer and amount of potassium, calcium and nitrogen contents of corm dry mass. Among nitrogen levels, 20 gcm-2N caused an increasing in leaf number mean, flower fresh weight and corm yield (fresh weight mean, corm diameter and cormlet numbers). Nitrogen had no effect on plant height, corm dry weight percentage and amount of potassium, calcium and nitrogen in corm dry mass.