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- Author or Editor: Richard A. Criley x
- Journal of the American Society for Horticultural Science x
Abstract
Three substances with gibberellin-like activity in the dock and barley endosperm bioassay systems were detected in the root exudate of poinsettia cultivar ‘Paul Mikkelsen’. In the isopropyl ether:acetic acid (95:5, v/v) solvent system on 250 µ layers of silica gel G, these substances had Rf values of 0–0.1, 0.4–0.6, and 0.7–0.8. The extracted exudate material at Rf 0–0.1 generally showed greater activity in plants grown under long day conditions while the relative proportion of the other 2 fractions to the first increased under short day conditions. Following a drench with (2-chloroethyl) trimethylammonium chloride (Cycocel), the activity of all 3 fractions was reduced in comparison to the control. The Rf 0–0.1 material evidenced lower activity in relation to the other 2 fractions in exudate from Cycocel spray-treated plants.
Abstract
A technique using 2-branched rooted cuttings of azalea ‘Hexe’ was devised to provide uniform plant material for studying the effect of photoperiod and growth regulators on early stages of flower bud initiation and development. Flower initiation was most rapid under 8-hr daylengths, as a definite change of shape of apex was observed the 4th to 5th weeks. No change was observed on plants subjected to interrupted nights with 50 ft-c incandescent light supplied between 10 pm and 2 am.
Short days plus a drench of 0.4 g Cycocel, (2-chloro-ethyl) trimethylammonium chloride, accelerated initiation over short days alone. Gibberellic acid applied to Cycocel-treated plants at 3 and 4 weeks of short days delayed flower initiation. Gibberellic acid applied to short day plants during the 4th to 6th weeks was effective in preventing flower initiation in this cultivar.
Abstract
A short daylength of 8 hours was significantly more effective than daylengths of 14 to 14.5 hours in the early and continued initiation of inflorescences of Bougainvillea glabra Choisy cv. Carmencita. There was no statistically significant effect of 3 growth retardants, (2-chloroethyl)-trimethylammonium chloride, (Chlormequat), succinic acid-2,2-dimethylhydrazide, (daminozide), or α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol, (ancymidol), upon the enhancement of flowering in this double cultivar. There was little variation in the number of nodes to the first inflorescence when the plants were grown outside under full sunlight, but some delay was encountered as the days lengthened for plants grown in a shaded greenhouse. Flowering was low during the summer months for the greenhouse-grown plants and only slightly higher for the outdoor plants. Short daylengths (9 hours) with full sun produced the most floriferous plants. It is suggested that growth retardants may not be needed, given proper culture and daylength control, in a program of year around flowering.
Abstract
Terminal cuttings of Protea neriifolia R. Br. gave earlier rooting and superior rooting index values when they received basal pretreatments of combinations of (2-chloroethyl)phosphonic acid (ethephon) at 300 ppm and indoleacetic acid (IAA) at 4000 ppm followed by a commercial rooting preparation composed of 1.0% indolebutyric acid (IBA) plus 0.5% NAA diluted 1:9 and combinations of 2500 or 4000 ppm butanedioic acid mono-(2, 2-dimethylhydrazide) (daminozide) with 4000 ppm of IBA or IAA. Treatment effects were evident after 3 and 4 months while the control required 5 to 6 months for similar rooting results.