The effects of growth-retarding chemicals on stem anatomy were compared on poinsettia (Euphorbia pulcherrima Wind. `Annette Hegg Dark Red'). Micrographic examinations revealed that secondary walls of nonsclerotic phloem fiber cells were either completely or greatly reduced by retardant treatment. Wall thickening of phloem fiber cells was eliminated by paclobutrazol foliar sprays at 25 mg·liter-1. Fiber cell development was reduced, but not eliminated, by sprays of chlormequat and ancymidol at standard rates, while the triazole uniconazole at 10 mg·liter-1 permitted only limited fiber wall thickening. Chemical names used: (2-chloroethyl)-trimethyl ammonium chloride (chlormequat); α -cyclopropylα- (4-methoxyphenyl) -5-pyrimidine methanol (ancymidol); (E)-(p -chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol (uniconazole): and (R*,R*)- β -[(4-chlorophenyl)methyl]- α -(1,1-dimethylethyl)- 1 H-1,2,4,triazole-1-ethanol (paclobutrazol).
Abstract
Paclobutrazol was found to be an effective growth retardant for weeping fig (Ficus benjamina L.). Plants treated with a soil drench at rates of application from 0.125 mg a.i. to 8.0 mg a.i. per 10-cm pot exhibited retardation in plant height, leaf production, internode length, and leaf size. All measured responses were retarded linearly with increasing concentration, to the point of saturation at 0.5 mg a.i. per 10cm pot. Leaves developing under the influence of paclobutrazol also appeared darker green than in untreated plants. The growth retarding influence of a single application of PP333 persisted after transplanting. Chemical names used: (2RS,3RS)-l-(4-chlorophenyl)-4,4-dimethyl-2(l,2,4-triazole-l-yl)pentan-3-ol (paclobutrazol; ICI-PP333).
Abstract
‘Mace’ kalanchoe usually produces dense foliage with a cluster of long cymes, but under optimal growing conditions plants grow excessively tall and quality is decreased. Growth retardation of ‘Mace’ has been achieved with daminozide (2), chlormequat (Carlson, unpublished data), ethephon (3), and ancymidol (3). Of these four compounds, ancymidol was the most effective The present study was conducted to determine the effect of increasing ancymidol concn applied at specific time periods during flower inducing (short day) conditions.
Abstract
Foliar applications of 100 to 150 mg (ai/liter of an aqueous solution containing 5% of 1-allyl-l -(3, 7-dimethyloctyl) piperidinium bromide (piproctanyl-bromide, Stemtrol), reduced the height of all chrysanthemum cultivars tested. Best results were obtained when applied to cuttings 5 to 10 days after the beginning of propagation followed by a second application when the axillary shoots were 2 — 3 cm long. Penetration and translocation to the apical meristems were better through young, soft leaves near the apex than through older bottom leaves. The growth retardation effect of piproctanyl-bromide was independent of nutrient level.
Abstract
Height of potted chrysanthemums (Chrysanthemum × morifolium Ramat.) was effectively controlled by soil drench applications of paclobutrazol [ICI-PP-333 = (2RS, 3RS)-l-(4-chlorophenyl)-4,4-dimethyl-2-l,2,4-triazol-l-yl-pentan-3-ol]. While response to the chemical depended on normal flowering height of each cultivar, rates of 0.125–0.750 mg ai/15-cm pot were effective on the tall- and medium-height cultivars tested. Aqueous foliar sprays were ineffective in controlling plant height. Foliar sprays of paclobutrazol mixed in 15% ethanol caused significant height reduction of chrysanthemum. Foliar sprays were not as effective as soil drench applications for controlling growth.
Abstract
A single spray application of succinic acid-2, 2-dimethylhydrazide (daminozide) at 2,500-15,000 ppm at pinch was effective in retarding growth of bleeding heart, reducing plant height 33 to 75%. A single spray or drench of (2-chlorethyl) trimethylammgrium chloride (chlormequat) had little retarding influence. Spray application of (2-chloroethyl) phosphonic acid (ethephon) had little effect on plant height, but considerably increased the number of nodes and delayed flowering.
Abstract
Aqua-Gro (50% polyoxyethylene ester, 50% polyoxyethylene ether), a nonionic commercial surfactant, retarded growth and reduced yield of Zea mays L. ‘Golden Bantam’ and ‘XL-367’ when a 1,000 ppm aqueous solution was applied to the foliage. There was seemingly no toxic effect on Pisum sativum L., Cucumis melo L., or Citrullus vulgaris Schrad.
Abstract
Compared with manual pruning, use of fatty acid pruning compounds (Emgard, Off-Shoot-O and C-10) increased time to bloom for Rhodedendron obtusum Planch ‘Alaska’ and ‘Red Wing’ and decreased flower number on ‘Alaska’. Pruning compounds interacted with succinic acid-2,2-dimethylhydrazide (SADH) and (2-chloroethyl)triethylammonium chloride (chlormequat) as well as frequency of application in affecting date of bloom and number of flowers.
Abstract
The growth-retardant activity of 4 quaternary ammonium derivatives of (+)-limonene was determined by application of foliar sprays on greenhouse-grown grapefruit seedlings. The most active compound was 1-p-men-thanol-2-dimethylamino heptyl bromide. The 3,4-dichlorobenzyl chloride and p-methylbenzyl chloride quaternary ammonium derivatives of 2-dimethylamino-1-p-menthanol were occasionally rated as highly active, but in some tests these compounds were either only slightly active as growth retardants or moderately active as growth stimulators. The 2,4-dichlorobenzyl chloride derivative was only moderately active on grapefruit seedlings. Alar in some tests was moderately effective as a growth retardant, and in other tests it was either inactive or somewhat active as a growth stimulator. The heptyl derivative at 3000 and 6000 ppm was also effective in reducing growth of 3-year-old field-grown lemon trees for a relatively short period of time. A 1000 ppm application appeared to stimulate growth of lemon trees and grapefruit seedlings.
Abstract
Tomato plants (Lycopersicon esculentum) infected with root-knot nematodes, Meloidogyne javanica, contain 2.2 to 2.6-times higher levels of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in the roots and leaves compared with uninfected plants. The nematode-induced increase in the ACC coincides with increased ethylene production in the infected plants. Foliar spray with aminoethoxyvivyl-glycine (AVG), which inhibits ethylene production or with silver thiosulfate (STS) which inhibited ethylene action, partially or completely eliminated the pathogenic symptoms displayed by a nematode-infected plant, indicating that the ethylene induced by the nematode infection plays a major role in the pathogenic symptoms infliced by the nematode. Foliar spray with 3 mM STS 4 to 8 days after the nematode inoculation was found to be the most effective treatment for reversing the nematode infection symptoms.