Effect of Some Growth Regulators on Growth, Flowering, Bulb Productivity and Chemical Composition of Iris Plants

This investigation was carried out at the Nursery of Ornamental plants, Faculty of Agriculture, Minia University, Egypt during the two successive seasons of 2008 / 2009 and 2009 / 2010 to study the effect of different concentrations of gibberellins (GA ), cycocel (CCC) and Alar on the growth, flowering and bulb 3 production of iris plants. In this study the plants of iris were sprayed three times with 0, 250, 500 and 750 ppm of GA , 250, 500 and 1000 ppm of CCC and 125, 250 and 500 ppm of Alar. Results showed that GA treatments 33 significantly increased leaf length, while, CCC and Alar treatments significantly decreased the leaf length compared to control treatment. GA treatments shortened significantly the time taken from planting to flowering, 3 while CCC and Alar treatments significantly delayed the flowering date compared to control. Also, the flowering stalk length was increased by application of GA at the three used concentrations, while, CCC and Alar at the 3 same concentrations led to decrease in the flowering stalk length. The positive or negative effects of GA3 or CCC and Alar were gradually increased by increasing their concentrations. All treatments of GA , CCC and 3 Alar led to increased flowering stalk diameter, fresh and dry weights of the flowering stalk and fresh weight of inflorescence / plant compared to control. The best results were obtained by using of high concentration of GA , CCC and Alar. All GA , CCC and Alar treatments had a stimulatory effect on the formation of new bulbs 33 and bulblets compared to the control treatment. The highest of fresh weight of new bulbs and bulblets / plant and the highest number of bulblets / plant were obtained by the application of GA at 750 ppm, CCC at 1000 ppm 3 and Alar at 500 ppm. Total chlorophyll content of the leaves was increased as a result of using different concentrations of CCC or Alar. Meanwhile, total chlorophyll content was decreased by the application of the three used concentration of GA compared to the control. The highest percentage of the total carbohydrates 3 in the bulbs was obtained by the application of GA at 750 ppm followed by CCC at 1000 and Alar at 500 ppm. 3