‘Nellie White’ Easter lilies were treated with either ancymidol or paclobutrazol as a soil drench (1, 2.5, or 5 mg·pot−1) or as a foliar spray (5 mg·plant−1). Ancymidol significantly retarded plant height at all concentrations and for both methods of application. In addition, ancymidol, at 5 mg·pot−1 soil drench, increased days to anthesis. Paclobutrazol did not retard height in this cultivar; in fact, the 2 lower rates increased height slightly and decreased days to anthesis. Plant height of ‘Ace’ Easter lilies was reduced by paclobutrazol treatments (5,10, or 20 mg·pot−1 soil drench). This cultivar, however, was also more sensitive to ancymidol treatment than ‘Nellie White’. Rates >1 mg ancymidol excessively retarded plant height. Paclobutrazol appears to have limited potential as a growth retardant for Easter lily. Although it must be used in higher amounts than ancymidol to control stem growth, it provides commercially acceptable height retardation over a wider range of treatment rates. Chemical names used: α-cyclopropyl-α-[4-methoxyphenyl]-5-pyrimidinemethanol (ancymidol); and β-[(4-chlorophenyl)methyl]-α-(l,l-dimethylethyl)-lH-l,2,4-triazole-l-ethanol (paclobutrazol).
Freesia (Freesia hybrida Bailey) corms were treated with paclobutrazol or ancymidol as a 5 mg a.i. soil drench, or with paclobutrazol as a 250 ppm preplant corm soak treatment. Both growth retardants significantly reduced plant height and inflorescence length, but had no effect on number of flowering spikes per pot or number of days to flowering. The preplant corm soak treatment was even more effective for height control than the soil drench application. Both compounds can be used to reduce plant height, allowing the adaptation of freesia to pot plant culture. Chemical names used : β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4 triazole-1-ethanol (paclobutrazol) and α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidi nemethanol (ancymidol).
Six genotypes of apple with a range in bloom date of 18 days were used to determine the contribution of the postdormant heat requirement to time of flowering. Spurs containing flower buds were collected after the chilling requirement had been satisfied but before detectable bud growth had begun, and forced at 10°, 15°, or 20°C. Bud development occurred on all samples at 20°, although at different rates which were correlated directly with field bloom date. At 10°, the genotypes fell into 2 groups. The first, consisting of the 3 earliest flowering selections, developed more slowly at 10° than at 20°. The 2nd, consisting of the 3 latest flowering selections, did not grow at all at 10°. The data suggest that late flowering in apple results from high heat and high minimum temperature requirements for bud growth, not from high chilling requirement.
Aquilegia cultivars `Songbird Bluebird', `Songbird Robin', `Dove Improved', `Colorado Violet/White' and five cultivars from new experimental genetic lines (`Red and White', `Rose and White #1', `Rose and White #2', `Scarlet and Yellow' and `White') will flower without vernalization, but little is known of their response to light or plant growth regulators. Plants were started from seed on 5 Jan. 1999 and grown in either natural light or 33% shade, and treated with gibberellins (GA4/7) at the seven-leaf stage. Flowering time, number of flowers/plant, and plant height were evaluated through 31 May 1999. All five cultivars from the new genetic lines bloomed during the study. `White', grown in shade and treated with GA4/7, bloomed 2 weeks earlier (115 days) than untreated plants grown in natural light (130 days). `Songbird Robin', treated with GA4/7, bloomed in 146 days, and was the only other cultivar to bloom. Flower numbers were greater in natural light than in 33% shade. GA4/7 increased flowering for four of five cultivars, in the new genetic lines, grown in natural light. In shade, GA4/7 increased flowering for three of five cultivars. Height response to GA4/7 was significant in both natural light and 33% shade. Four of the five cultivars in the new genetic lines were taller when treated. All five of these cultivars were taller when grown in natural light verses 33% shade. `White' and both `Rose and White' cultivars were consistently taller, bloomed earlier and were more floriferous when treated with GA4/7.
Internode elongation in lily (Lilium longiflorum Thunb.) increased significantly in the uppermost internodes during the development of the flowers. The last 4 internodes contributed as much to plant height as the first 30 internodes. Removal of the flowers reduced internode elongation, and within the range of 1–4 flowers per plant, length of the uppermost internodes was directly related to flower number. Removal of the perianth of the flowers was almost as effective as defloration in reducing internode growth. Application of gibberellic acid to decapitated stems completely replaced the effect of the flowers, whereas indoleacetic acid was only partially effective in restoring internode growth.
Lilies (Lilium longiflorum Thunb.) were treated with ancymidol (A-Rest), propiconazol (Banner), triadimefon (Bayleton), or Mobay RSW0411 as a soil drench or as a preplant bulb soak. At high rates the fungicides triadimefon and propiconazol reduced Easter lily plant height. Neither propoiconazol nor triadimefon were as effective as Mobay RSW0411 or ancymidol in reducing plant height; however, results suggest that chemical treatments for disease and height control may be achieved with the same treatment. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); 1-(2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl)-1H-1,2,4-triazole (propiconazol); 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)-2-butanone (triadimefon); β-(cyclohexylmethylene)-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (Mobay RSW0411).
Ethephon at 200 ppm applied to ‘Cresthaven’ peach trees [Prunus persica (L.) Batsch] in October delayed flowering by 7 days in the first year of this study, but only by 3 days in the 2nd year. Flower bud survival was reduced in both years by this treatment, although the percentage of fruit set increased. The differences observed in the effectiveness of ethephon in delaying bloom may be due to differences in spring temperatures during bud expansion. High temperatures during the period of bud expansion tended to accelerate bud development, minimizing the effect of treatment, whereas low temperatures during this period tended to accentuate treatment effects. GA3 applied in October delayed leaf senescence and abscission, but did not delay flowering.
Precocious flowering can be induced in asparagus (Asparagus officinalis L.) seedlings with N-phenylcarbamate herbicides, such as n-propyl N-(3,4-dichlorophenyl) carbamate (NPC); however, only ≈50% of the treated seeds produce flowering plants because these compounds inhibit germination and seedling emergence. We have improved the treatment method by determining the environmental conditions, timing, dose, and duration needed to maximize the percentage of germination, emergence, and flowering. Imbibing seeds in water for 5 days, and then treating germinated seeds with 0.4 mm NPC for 5 days after radicle emergence, with seedling aeration in the light, resulted in the production of flowering seedlings from >90% of the treated seeds. For freshly harvested seeds, in which germination rates are more variable than aged seeds, individual seedlings must be transferred to NPC within 1 day after radicle emergence to produce a high percentage of flowering plants. For seven male asparagus cultivars, chemical induction of flowering in seedlings with NPC produced a sex ratio similar to that of field-grown plants, demonstrating that NPC induces flowering without altering floral differentiation or sex expression. This method can be used for rapidly and accurately identifying the percentage of females in “male” cultivars.