| dc.description.abstract | These investigations were conducted to determine the
effect of growth regulators and environmental factors on the
growth and flowering of Clerodendrum thomsonae Balf. "Wisconsin"
clone. Whether terminal or stem-bud cuttings were
used, there was little difference in growthand flowering of
the plants. plants propagated from cuttings taken from the
uppermost portion of the stem of young stock plants (four
months) developed about five times as many flowers as t.hose
from old stock plants (one and one-half years). plants
defoliated and water stressed for one week produced axillary
shoots at 79% of the nodes compared to axillary shoots at
5.3% of the nodes of non-defoliatE:d and non-water stressed
plants.
Of eight different media used, a peat-vermiculite-sand
medium was most satisfactory for growth-a-nd flowering. plants grown in a medium at pH (6.9) and treated with
ancymidol (30 ppm used as a drench at the rate of 30 ml/four inch
pot) produced more -flowers than plants grown in media
with a pH of 5.0 or lower.
Ancymidol treated piants had twice the concentration
of N, P, and K present in untreated plants. plants receiving
as low as 80 ppm N and as high as 320 ppm N showed
little difference in growth and flower development.' The
dry wt of leaves, stems, and roots decreased with increased
ancymidol concentrations.
plants grown from stem-tips given heat therapy were
virus free and produced the same number of flowers as plants
that did not receive heat therapy.
Elongation of untreated plants was considerably greater
than ancymidol treated onp.s regardless of photoperiod;
whereas, there was little effect of light intensity on the
elongation of treated and untreated plants. Ancymidol
treated plants produced as much as a 50-fold increase in
flowers compared to untreated ones. In controlled environment
chambers, fewer flowers were produced under low light
intensity (under 1200 ft-c) than under high light intensity
(6500 ft-c). plants exposed to ~ hour of red light before
the dark period in both sl)ort and long days flowered profusely;
whereas, those exposed to Ear-red remained vegetative.
Of the numerous growth regulators tested, encapsulated
cycocel and ancymidol stimulated flowering and inhibited
excessive elongation. Studies on the former were discontinued
because of severe chlorosis and leaf distortion.
Morphactin stimulated axi.llary shoot development, but also
caused extensive apical and foliar injury.
Ancymidol retarded growth of plants whereas gibberellic
acid (Gl'l.3) only and GF_3 plus ancyrnido L promoted stem
elongation. Untreated and ancymidol treated plants grown
under a IS-hour photoperiod remained' vegetative, but
flowered under a 12-hour photo period , Plants treated with
GA3 and GA3 plus ancymidol remained vegetative in both 12
and 15-hour photoperiods.
Anatomical examinations of the stem tips revealed that
ancymidol enhanced the early development of floral parts
however, untreated plants flowered at nearly the same time
as treated ones. 'The reason for this may 'be that the greater
number of flowers produced on ancymidol treated plants require
a greater amount of photosynthate. There was a
striking increase in gibberellic acid in flowering compared to
vegetative plants. The Effeciveness of ancymidol to
increase the GA concentration which may induce plants to
flower strengthens the hypothesis that ancymidolI does not
interfere with inhibition of GA3 biosynthesis | en |
