Pre-harvest foliar application of iron sulfate and citric acid combined with urea fertigation affects growth and vase life of tuberose (Polianthes tuberosa L.) 'Por-Par'

The effect of foliar application of citric acid (0, 0.05, or 0.1%, w/v) and iron sulfate (0, 0.5, or 2%, w/v) combined with nitrogen fertigation (0, 100, 150, or 200 mg center dot L-1 N supplied as urea) on flower stalk length, inflorescence length, number of florets, bulblet size, total iron content, and vase life of tuberose was studied. The study was conducted in a randomized factorial design arrangement (3 citric acid levels x 3 iron sulfate levels x 4 nitrogen fertigation levels) with three replications. Four sprays were conducted at every 14 days after the first spray at the 4 to 5 leaf stage. Foliar citric acid spray significantly increased the average vase life. Foliar iron sulfate spray effectively increased total tissue iron content and vase life. The longest vase life was observed with a combination of 150 mg center dot L-1 nitrogen, 2% (w/v) iron sulfate, and 0.1% (w/v) citric acid. Nitrogen fertigation increased all vegetative growth indices, including flower stalk length, inflorescence length, and number of florets, and vase life, especially at 150 mg center dot L-1 N. This nitrogen level, when combined with 0.5% (w/v) iron sulfate and 0.05% (w/v) citric acid, yielded larger sizes of bulblets than other treatments as well.