Some Effects of Indol-3-ylacetic Acid on the Rates of Initiation and Development of Flower Buds of Chrysanthemum morifolium

Abstract

Frequent applications of a solution containing 50 p.p.m. IAA to the upper leaves of Chrysanthemum plants reduced the numbers of open and opening flowers and delayed harvesting. The rates of initiation and development of flower buds were studied by dissection in relation to the concentrations of indol-3-yl-acetic acid (IAA) (20–200 p.p.m.) applied to the tops of the plants. Inereasing the concentrations of IAA resulted in a progressive delay in bud initiation (P<0⋅001), but had little effect on their subsequent rates of development. The results differed from those previously obtained with copper deficient plants in that the latter deficiency affected both initiation and development of the buds.