EFFECTS OF NAPHTHALINEACETIC ACID, SALICYLIC ACID AND SPERMIDINE ON GROWTH AND BULBING OF ONION PLANT

Abstract

The present study was conducted in the Experimental Farm, Faculty of Agric., Ain Shams University during seasons 2202/2003 and 2003/2004 to investigate the effect of the following growth regulators; naphthalineacetic acid (NAA) at 25 and 50 ppm, salicylic acid (SA) at 10 and 20 ppm, and spermidine (Spd) at 10 and 20 ppm on growth and bulbing of onion (Allium cepa L.) plant. Growth regulator treatments were applied as 3 foliar sprays started at 10 weeks from transplanting, with one week interval. Two samples were taken, the first one were taken at 14 weeks from transplanting. The second sample was taken at harvesting. NAA at 50 ppm increased plant height and blades fresh weight. At harvesting time, all growth regulator treatments increased bulb size, bulbs fresh and dry weight. Spd at 10 ppm gave the highest values of bulb size and bulbs dry weight. The highest bulbs fresh weight was attained by NAA at 25 ppm. Growth regulator treatments reduced total soluble carbohydrates in blades comparing with control in the first sample. On the other hand, an increase in total soluble sugars was detected in blades by treatments. Spd at 10 ppm and NAA at 50 ppm showed significant increase in total soluble sugars and vitamin C in bulbs at harvesting time. SA at 10 and 20 ppm showed significant increase in phenols concentration in blades. The effect of plant growth regulators NAA, SA and Spd on growth, bulbing of onion plant and correlated components " total soluble carbohydrates and sugars, indoles, total soluble phenols and vitamin C" were discussed