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To evaluate importance of paclobutrazol residues on surfaces, begonia (Begonia semperflorens) cv. Whisky and chrysanthemum (Dendranthema grandiflora) cv. Coral Davis plants were grown in flats sprayed with paclobutrazol at 0, 50, 100, 200 and 400 ppm.

For begonia, the plant heights at 2 and 4 weeks after treatments were decreased by 39 to 49% and by 55-69%, respectively. The overall change in height ranged from 2.1 to 4.9 cm compared to 15.3 cm for the control plants.

For chrysanthemum, a reduction in plant height was observed and the overall change in height ranged from 2.9 to 5.6 cm compared to 28.8 cm for the control plants.

Based on these results, there is a potential for paclobutrazol to affect non-target plants when subirrigation is used.

Trees were grown for 2 years as a function of three container volumes (10, 27, and 57 liter) the first year and six shifting treatments (10 liter both years, 10 to 27 liter, 10 to 57 liter, 27 liter both years, 27 to 57 liter, or 57 liter both years) the second year when containers were spaced 120 cm on center, Height and caliper were greatest for magnolias grown in 27- or 57-liter containers both years. Caliper was greater for trees shifted from 10-liter containers to the larger container volumes compared to trees grown in 10-liter containers both years, Trees grown in 10-liter containers both years tended to have few roots growing in the outer 4 cm at the eastern, southern, and western exposures in the grow medium, During the second year, high air and growth medium temperatures may have been primary limiting factors to carbon assimilation during June and August. Using large container volumes to increase carbon assimilation and tree growth may be even more important when daily maximum air temperatures are lower during late spring or early fall compared to midsummer.

Dormant-budded `Gloria' azaleas (Rhododendron sp.) were used to observe the effect of forcing irradiance, temperature, and fertilization on postproduction performance after flower bud dormancy had been broken. Four experiments were conducted during forcing, the treatments for each experiment were: Expt. 1, three forcing irradiances (200,460, and 900 μmol·m^-2·s^-1) and three postproduction irradiances (4, 8, and 16 μmol·m^-z·s^-1); Expt. 2, three forcing irradiances (320, 560, and 1110 μmol·m^-2s^-l); Expt. 3, three controlled day/night temperatures (18/16C, 23/21C, and 29/27C); Expt. 4, fertilizer applied for 7, 14, or 28 days at either 150 or 300 mg N/liter (12% nitrate, 8% ammoniacal) 20N-4.8P-16K soluble fertilizer at every watering, control plants did not receive fertilizer. Days to harvest (time until plants had eight individual open flowers) was less at the high forcing irradiances and temperatures and when fertilizer was applied during forcing. Flower color was less intense at the low forcing irradiance levels, high temperatures, and when duration of fertilization was prolonged and concentration was high. There were more open flower inflorescences at week 2 of postproduction at high forcing irradiance levels, but their number was not affected by forcing temperature or fertilization. Postproduction longevity was shorter when forcing was at 29/27C (day/night) and when plants were fertilized for 28 days at 300 mg N/liter, but was not affected by forcing or postproduction irradiance.

Five cultivars of potted miniature roses (`Candy Sunblaze', `Lady Sunblaze', `Orange Sunblaze', `Red Sunblaze' and `Royal Sunblaze') were grown until stage 1 (bud showing color with sepals starting to unfold). At this stage one half of the plants were moved to interior conditions (12 μmol s<sup>-1</sup> m<sup>-2</sup> from cool white fluorescent lights for 12 hr daily and 21 ± 1C) and the other half were maintained in the greenhouse at recommended production conditions. Stage 1 bud respiration, flower respiration at flowering and at 2, 4, 6 and 8 days after flowering were assessed for plants in the greenhouse and under interior conditions. Also, flower interior longevity was assessed for all the cultivars and the correlations between flower longevity and flower respiration at the different stages were analyzed. At flowering and under interior conditions `Red Sunblaze' lasted the longest (23 days) followed by `Orange Sunblaze' (18 days), `Lady Sunblaze' and `Candy Sunblaze' (16 days), and `Royal Sunblaze' (13 days) and flower respiration was 2.08, 2.74, 3.91, 3.59 and 3.94 mg CO₂ g^-1 hr^-1, respectively. In miniature rose, flower longevity was negatively correlated with flower respiration rate (P = 0.01).

Research was conducted to investigate the relationship between flower respiration and flower longevity as well as to assess the possibility of using miniature rose (Rosa hybrida L.) flower respiration as an indicator of potential flower longevity. Using several miniature rose cultivars as a source of variation, four experiments were conducted throughout the year to study flower respiration and flower longevity under interior conditions. For plants under greenhouse as well as interior conditions, flower respiration was assessed on one flower per plant, from end-of-production (sepals beginning to separate) up to 8 days after anthesis. Interior conditions were 21 ± 1 °C and 50 ± 5% relative humidity with a 12-hour photoperiod of 12 μmol·m^-2·s^-1 (photosynthetically active radiation). Flower respiration was higher if the plants were produced during spring/summer as compared to fall/winter. `Meidanclar', `Schobitet', and `Meilarco' miniature roses had higher flower respiration rates than `Meijikatar' and `Meirutral'. These two cultivars with the lowest respiration rates showed much greater flower longevity if grown during spring/summer as compared to fall/winter. The three cultivars with the higher respiration rates did not show differences in flower longevity between seasons. For plants under greenhouse or interior conditions, flower respiration was negatively correlated with longevity in spring/summer but a positive correlation between these parameters was found in fall/winter. During spring/summer, flower respiration rate appears to be a good indicator of potential metabolic rate, and flowers with low respiration rates last longer.

Paclobutrazol was applied as soil drench to potted petunia, and the treated plants were shorter than untreated ones. Three types of compost were then made from the treated and untreated plants: the shoots, the medium (including roots), and both shoots and medium. They were mixed with Vergro Klay Mix at the ratios of 0%, 5%, 10%, 20%, and 40% (v/v). In a factorial experiment, plugs of Begonia semperflorens cv. Gin were planted in the media with compost. Plants grown in media containing paclobutrazol residue were shorter and had less dry weight compared to those grown in media containing no paclobutrazol residue. Compost ratios at 5% and 40% reduced plant height to 65% and 42% and shoot dry weight to 55% and 20% of the control plants, respectively. These results indicate that residues from plants treated with paclobutrazol may carry over in soil of landscape beds and affect the growth of subsequent crops grown in that soil.

The effect of two temperature regimes (29 °C day/24 °C night and 24 °C day/18 °C night) and of a 4-hour night interruption, during production, was studied on postproduction flower longevity and bud drop of 'Meirutral' and 'Meidanclar' potted, miniature roses (Rosa L. sp.). High production temperatures increased postproduction flower longevity and decreased postproduction bud drop. In 'Meidanclar', the high production temperature increased incidence of malformed flowers. No effects of night interruption could be shown on either postproduction flower longevity or bud drop.

Paclobutrazol drench treatments were evaluated for efficacy on Caladium ×hortulanum (Birdsey) cultivars Aaron, White Christmas, and Carolyn Wharton. Drenches at 2.0 mg/pot did not reduce height of `Aaron' and `White Christmas' plants when applied 1 week after planting, but 2.0 mg applied at 3 weeks after planting did result in shorter plants. The difference for time of application may be due to the amount of roots present to take up paclobutrazol when applied. In two factorial experiments, there were no interactions between cultivar and time of application or amount of chemical. Paclobutrazol at 0.5 mg/pot resulted in plants that were shorter than the controls. Higher amounts of paclobutrazol provided additional reductions in height, but there was variation between the experiments for degree of effect with amounts >1 mg. Generally, commercially acceptable height control was provided by paclobutrazol drench treatments at 0.5 and 1.0 mg/pot applied 3 weeks after planting. Chemical names used: (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazol-1-yl-pentan-3-ol (paclobutrazol).

Growth of Magnolia grandiflora Hort. `St. Mary' (southern magnolia) trees in containers spaced 120 cm on center was studied for 2 years. During the 1st year, trees were grown in container volumes of 10, 27, or 57 liter. At the start of the second growing season, trees were transplanted according to six container shifting treatments [10-liter containers (LC) both years, 10 to 27LC, 10 to 57LC, 27LC both years, 27 to 57LC, or 57LC both years]. The mean maximum temperature at the center location was 4.8 and 6.3C lower for the 57LC than for the 27 and 10LC, respectively. Height and caliper, measured at the end of 2 years, were” greatest for magnolias grown continuously in 27 or 57LC. Caliper was greater for trees shifted from 10LC to the larger containers compared with trees grown in 10LC both years. Trees grown in 10LC both years tended to have fewer roots growing in tbe outer 4 cm of the growing medium at the eastern, southern, and western exposures. During June and August of the 2nd year, high air and growth medium temperatures may have been limiting factors to carbon assimilation. Maintenance of adequate carbon assimilation fluxes and tree growth, when container walls are exposed to solar radiation, may require increasing the container volume. This procedure may be more important when daily maximum air temperatures are lower during late spring or early fall than in midsummer, because low solar angles insolate part of the container surface.

Four experiments using container-grown Dendranthema ×grandiflorum (Ramat.) Kitamura `Nob Hill' or `Tara' were conducted to determine effects of application site and spray volume on uniconazole efficacy. Uniconazole applied only to mature leaves was less effective in controlling stem elongation than were stem applications, whole-plant sprays, or medium drenches. Spray volume altered efficacy more for uniconazole than for daminozide. Also, the effect of uniconazole spray volume was greater when the medium was not covered than when covered to prevent spray solution entering medium. Results from these studies showed the efficacy of uniconazole increased with increased stem coverage and with amount of chemical reaching the medium, which was achieved with high spray volumes. Chemical names used: (E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol) (uniconazole); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide).