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- Author or Editor: Richard A. Criley 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
Chloroethyl-trimethylammonium chloride (chlormequat) was the most effective of several growth retardants in retarding new growth of field-grown of Hibiscus rosa-sinensis L. without serious side effects. A reduction by one-third to one-half of non-treated growth occurred for 1000 and 3000 ppm (active ingredient), respectively. Over 3½ year period of repeated shearings plus spray applications, 1500 ppm was the most satisfactory following each shearing, while 3000 ppm could be used with alternate shearings. The growth retarding effect of 3000 ppm chlormequat was carried over from previous applications when sheared growth was untreated.
As part of a research study on growth and flower production of 20 commercial heliconia cultivars, plants were established at the Waimanalo Research Farm (Oahu) of the Univ. of Hawaii in July 1999. This report focuses on Heliconia ×rauliniana. Five plants in 7.6 L pots were planted at spacings of 2.5 M in row, with between row spacings of 3 M. Beginning a month later, newly emerged shoots were tagged every four weeks. At flowering, the shoots were harvested and leaf counts made. The information derived from the data include time frame from shoot emergence to flower, rate of shoot production, percentage of shoots from each tag date that flowered and the periodicity of flowering in a two year period. The range of times from shoot emergence to harvest was 208 to 450 days. In the first 12 months following planting, the average cumulative new shoot production since planting was 77 shoots per plant, while more than 58 inflorescences per plant were produced from the tagged stems for a 75% productivity rating. H. X rauliniana evidenced periodic flowering behavior, with peak flowering in the April to June period, that suggested it is a short-day plant for flower initiation.
The flowers of pakalana are initiated under long days (LD) at 18C or above. At 21 and 24C, inflorescence initiation occurs after 3 weeks of LD, and the clusters grow to 6 mm in another 2 weeks, but at 18C, about 12 weeks are required to achieve the 6-mm length. This length is critical, as a shorter stage often fails to develop further. From a length of 6 mm, clusters develop to anthesis in 3 to 4 weeks at 24C, 4 to 5 weeks at 21C, and 6 to 7 weeks at 18C. This work is important to the production of pakalana flowers for Hawaii's winter lei flower trade.
Abstract
Abscission of young fruits of the coconut palm occurred following sprays of (2-chloroethyl)phosphonic acid (ethephon) and methyl-2-chloro-9-hydroxyfluorene-9-carboxylate (chlorflurenol) at 2500 and 5000 ppm, but not if the inflorescence was sprayed prior to the time pistillate flowers were receptive. Fruits ranging in diam from 4 to 8 cm abscised the most readily, but occasionally maturing fruit up to 20 cm diam were affected.