Abstract:
A series of 3 experiments was conducted from 1984 to 1986 to
determine the influence of ethylene gas treatments and ethephon
[(2-chloroethyl) phosphonic acid] dips, in combination with several
heat curing durations, on the performance of greenhouse-forced Blue
Ribbon and Ideal iris.
In the first study which examined the effects of ethylene gas
concentration and heat curing duration, a treatment consisting of 7
days of heat curing preceded by exposure of the bulbs to either 8
or 80 ppm ethylene resulted in the shortest greenhouse phase for
both cultivars. Average blooming date was reduced from 116 days
(untreated check) to 69 days (treated bulbs) with Blue Ribbon and
from 65 days to 51 days with Ideal.
In the second study which examined effects of ethephon dip and
heat curing duration, an ethephon (0.5 g a.i./l) dip for 1 hour
before 7 days of heat curing with Blue Ribbon or 3 days with Ideal
significantly decreased the length of time required for greenhouse
forcing. Compared to untreated checks, the average flowering date
of Ideal was 15 days earlier, while Blue Ribbon bloomed 21 days
earlier.
These same ethylene or ethephon treatments, generally, led to
a favorable reduction of sprouting time, leaf number per plant, and
leaf height. Treatment with either growth regulator increased
total flowering percentage, because of a reduction of blindness.
Results showed that ethylene or ethrel can be used to improve
forcing of bulbous iris grown in the Pacific Northwest.
In a third experiment bulbs from several size categories were
evaluated. Ethylene and ethephon treatments were compared, and
several heat curing durations were used. Treatments were based on
results of the first two experiments. Regardless of bulb size,
flowering percentage increased and the greenhouse period decreased
when ethylene at 80 ppm followed by 3 days of high temperature were
applied to the bulbs of either cultivar, or when an ethephon dip
for 1 hour prior to 3 days of heat in Ideal and 6 days in Blue
Ribbon were used. These treatments resulted in optimal
combinations for all variables evaluated.
