A study on plant height control of iris flowers.

Abstract

We investigated the effect of paclobutrazol as preplant bulb soaks on plant height of Iris x hollandica cv. ‘Frans Hals’ and ‘Blue Magic’cultivars which were grown in pots. Bulbs of iris were soaked into gibberellin inhibitor paclobutrazol solution at 0, 15, 30 ppm before planting. Effect of paclobutrazol on the flowering time, flower diameter and length, leaf length, plant height, flower life, and chlorophyll content of leaves were determined. The shortest plant height was obtained from the ‘Blue Magic’ cultivar treated with 30 ppm paclobutrazol which gave plants with 11.3 cm, 68% shorter than untreated control. ‘Frans Hals’ cultivar treated with 30 ppm paclobutrazol was 20.9 cm and 50% shorter than control. In ‘Blue Magic’ and ‘Frans Hals’cultivars the lower dose of 15 ppm paclobutrazol were also effective on height control with 11.8 and 21.5 cm plant height, respectively. This gibberellin inhibitor also shortened the leaf length of iris cultivars. Paclobutrazol treatments resulted in higher chlorophyll content per unit area in the leaves. The highest chlorophyll content (57.00 CCI) was obtained from the ‘Blue Magic’ iris treated with 30 ppm paclobutrazol, while the control plants had 32.70 CCI chlorophyll in their leaves. Chlorophyll content of ‘Frans Hals’ treated with 30 ppm paclobutrazol were 52.87 CCI, while control plants of this cultivar were 28.80 CCI. Plants applied with paclobutrazol resulted with smaller flower diameter compared to the control plants of both cultivars. The smallest flower diameter was obtained from 30 ppm paclobutrazol treatment with 38.83 mm in ‘Blue Magic’ iris while the control of this cultivar was 99.63 mm. The flower diameter of ‘Frans Hals’ cultivar treated with 30 ppm paclobutrazol was 109.1 mm, while the control one was 112 mm.