Search Results
Abstract
Plants of ‘#2 Golden Shoesmith’ and ‘Fred Shoesmith’ chrysanthemum (Chrysanthemum morifolium Ramat.) were grown in soil-filled greenhouse benches with soil heating by warmed water in buried pipes. During the growing period a soil temperature of about 23°C (21°-25°) initially increased stem elongation and shoot fresh weight of ‘#2 Golden Shoesmith’ plants compared with about 19° (17°-20°) or ambient (10.5°-15.5°). Both 23° and 19° later slowed stem elongation and decreased shoot and root fresh weights compared with ambient soil temperature. Soil temperature had little effect on growth and development of ‘Fred Shoe-smith’. Soil heating advanced harvest date by about 2 to 3 days, but did not affect dimensions or weight of inflorescence.
Abstract
Increased soil moisture stress reduced growth and transpiration rate of Ficus benjamina. Leaf drop during indoor phase was greater for plants previously watered during production at 3 day intervals than for plants grown under the 6- and 9-day water regimes.
Abstract
No appreciable signs of phytotoxicity were observed for 4 days following fumigation of plants (including begonias, petunias, snapdragons) with ozone of up to 80 parts per hundred million (pphm) or sulfur dioxide of up to 400 pphm for 2 hr. Thereafter, there was considerable necrosis, particularly on begonias fumigated with the highest concn of the pollutants. Growth suppression was reflected in reduced shoot and flower wt, and to a lesser degree in reduced flower number. Overall, begonias and petunias were the most sensitive. Coleus and snapdragons were moderately sensitive, while marigold, celosia, impatiens and salvia were tolerant. ‘White Tausendschon’ was the most sensitive begonia cultivar while blue-flowered ‘Capri’ was the most sensitive petunia. Mixed color petunias exhibited varying degrees of tolerance. ‘Scarlet Rainbow’ coleus was more sensitive than ‘Pastel Rainbow’. Measurements of growth alterations in plants were found very useful in determining latent forms of air pollutant injury.
Uniconazole was applied as a spray to the surface of container media prior to planting bedding plant plugs. This medium spray was compared to a standard whole-plant spray applied 2 weeks after planting. For petunia (Petunia ×hybrida Vilm.) and coleus (Solenostemon scutellarioides L.) the efficacy of the medium spray was similar to the whole-plant spray. However, for impatiens (Impatiens wallerana Hook. f.) and vinca [Catharanthus roseus (L.) G. Don.] the medium spray had greater efficacy than the whole-plant spray. Increased concentrations of uniconazole in the medium spray decreased plant height; however, the effect of higher concentrations was greater in a medium with out pine bark compared to a medium with pine bark as a component. In the above experiments, uniconazole was applied in a volume of 200 mL·m-2. In a test where spray volume varied, there was a negative linear relationship between plant height and spray volume. Chemical name used: (E)-(+)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ane-3-ol (uniconazole).
Abstract
Tulip bulbs (Tulipa spp.) were placed under ventilated low pressure storage (LPS) conditions for 14 days in either August or September. Compared to 760 mm Hg stored bulbs, LPS suppressed leaf growth and floral development. These effects were highly visible after storage in air at either 76 or 150 mm Hg and in the month of August. When tulip bulbs were forced, LPS treatments applied in August delayed flowering of most cultivars and flower size was occasionally reduced; in September treatments, LPS ventilation with additional O2 and CO2 accelerated flowering of 2 cultivars, but flower size was reduced. When stored under 76 mm Hg in air in August, most cultivars of hyacinth (Hyacinthus spp.) were subsequently delayed in flowering, but daffodils (Narcissus spp.) were not. Except for one cultivar of each species, LPS did not affect the percent of plants flowering, plant height or flower size. Penicillium growth on the bulb tunics was enhanced by humidifying the air under LPS conditions. It is concluded that LPS provides no advantages over the ventilated, temperature controlled units presently employed.
Abstract
Pinched plants of Chrysanthemum morifolium Ramat. ‘Orange Bowl’ and ‘Surf’ grown in a chamber maintained at 22° day/18°C night were transferred to 30° day/26° night at the beginning of week 1, 3, 5, or 7 after start of photoinduction period (15-hr nyctoperiod). Plants remained at high temperatures for 2, 4, 6, 8, or 10 weeks and then were returned to the 22°/18° chamber. Exposure to high temperatures during the first 4 weeks of short days increased the number of nodes, leaf area, stem length, and dry weight of leaves and stems. Rate of floret initiation and perianth differentiation decreased when exposed to high temperatures during the first 4 weeks of short days in ‘Orange Bowl’ but not in ‘Surf’. ‘Orange Bowl’ exposed to high temperatures for 10 weeks from the start of short days flowered 12 days later than plants grown at lower temperatures and formed bracteate buds. Flowering of ‘Orange Bowl’ grown at 22718° during the first 4 weeks of short days, then transferred to high temperatures, was not substantially delayed and flowers developed normally. Flowering was delayed 3 days when ‘Surf’ was exposed to high temperatures for 8 weeks from the start of short days. Exposure to high temperatures did not cause bracteate bud formation in ‘Surf’. With both cultivars, increasing the duration of high temperature exposure increased the time to flowering.