EFFECT OF PLANTING DENSITY, DEPTH OF PLANTING AND CHEMICAL FERTILIZATION ON GROWTH AND FLOWERING OF Iris hollandica

The experiment was conducted at a nursery in the city of Baghdad, during the time 2013/2014 season. The objective of the experiment was to study the effects of four planting density (1, 2, 3 and 4 bulbs pot-1 ), three depth of planting (3, 6, and 9 cm) and two levels of NPK fertilization (0 and 100 mg L -1) on growth and flowering of Iris hollandica cv. Prof. Blaauw. The studied parameters included number of days to flowering, plant height, flower diameter, flowering stem diameter, flowering stem fresh weight, vase life, fresh weight of new bulbs and fresh weight of bulblets. Plant density at (one bulb pot-1 ) produced the highest plant, largest flower, best stem diameter and heaviest fresh weight of flowering stem, while it gave the lowest fresh weight of bulbs and bulblets per pot. Depth of planting had a significant effects in increasing the number of days to flowering and fresh weight of the new bulbs, while it significantly decreased the fresh weight of the flowering stem. Fertilization significantly increased stem diameter, fresh weight of flowering stem and fresh weight of bulblets, while it significantly decreased the number of days to flowering. Interaction between depth of planting and fertilization and between plant density and fertilization had a significant effect on number of days for flowering and fresh weight of flowering stem respectively.