Influence of Potting Media, Temperature, and Concentration of Ancymidol on Growth of Chrysanthemum morifolium Ramat.1

Abstract

Influence of temperature, media and concentration of ancymidol (α-cyclopropyl-α-[p-methoxyphenyl]-5-pyrimidine-methanol) on the growth and flowering of selected cultivars of Chrysanthemum morifolium were studied. As day/night temperature increased or decreased from 22/18°C length of time required for the plants to come into flower increased. Stem elongation and leaf area decreased while fresh weight increased as temperatures decreased from 30/26° to 18/14°. Ancymidol applied at a concentration of 0.25 mg/pot of aqueous drench was sufficient to control height of plants grown in most media except pine bark humus. Incorporation of river sand, greenhouse soil or Ca(OH)2 into pine bark humus increased ancymidol's effectiveness. Increasing growth regulator concentration also resulted in adequate height control for plants grown in pine bark humus.

Chrysanthemum Height Control by Ancymidol, PP333, and EL-500 Dependent on Medium Composition1,2

“…The ancymidol drench resulted in re duced shoot elongation in both media com pared to untreated plants, but the plants in the medium without pine bark were shorter than plants in medium with pine bark. The reduced growth retardant activity in media with pine bark was similar to that reported by other researchers (4,8,12).…”

“…The binding of the growth retardants by pine bark probably is not a cation exchange mechanism, as is likely for K (5) and NH4 (9), since other media components such as peat that have a high cation exchange ca pacity should have a similar effect. However, in this study and others (4,8,12), the chem icals had more activity in peat mixtures than in pine bark mixtures. Also in this study, the cation exchange capacity for Vergro Klay Mix (0.51 me/g or 0.07 me/ml) was higher than for the medium with bark, Metro Mix 300 (0.27 me/g or 0.05 me/ml) (J. N. Joiner and T. A. Nell, unpublished).…”

“…One report indicated that ancymidol but not chlormequat had reduced effectiveness with pine bark (8). Pine bark's effect is un affected by temperature within the range at which plants are normally grown (4) but the effect is overcome by increasing the appli cation rate by a factor 2 or 3 (4,12). In a study comparing movement of ancymidol through 30.5 cm columns of soil-sand or pine bark-sand mixtures, Tschabold et al (12) ob served that 61 % of the recovered ancymidol was found in the leachate from soil-sand mix ture after heavy leaching and the remaining chemical was fairly evenly spread through the column.…”

“…Ancymidol, which has the broadest spectrum of the currently used compounds, suffers from reduced effectiveness when applied as a drench to a medium with pine bark as a component (4,8,12). Since ancymidol and EL-500 are substituted pyrimidines and because of the rapidly expanding use of container media with pine bark as a component, the effect of pine bark on the action of EL-500 and PP333 was evaluated.…”

Response Surface Analysis of Flowering in Chrysanthemum ‘Bright Golden Anne’

“…In the summer, decreasing day and night temperature is predicted to decrease time to flower by 10 days, decrease stem length 2 cm, and increase flower area by 80%. The temperature responses observed are expected both in direction and relative magnitude (2,3,6,13,29,30,31).…”