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Nicacio Cruz-Huerta, Jeffrey G. Williamson, and Rebecca L. Darnell

60% flattened and deformed fruits and thus are unmarketable ( Ali and Kelly, 1993 ; Aloni et al., 1999 ). Several reports have previously addressed the effect of low night temperature (LNT) on flower and fruit development and malformation in sweet

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Rebecca L. Darnell, Nicacio Cruz-Huerta, and Jeffrey G. Williamson

temperature and carbohydrate availability ( Aloni et al., 1999 ; Tomer et al., 1998 ). Low night temperatures (15 °C or lower) negatively affect bell pepper fruit quality. One of the more striking effects of LNT on pepper flower development is an increase in

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F. Todd Lasseigne, Stuart L. Warren, Frank A. Blazich, and Thomas G. Ranney

research was to characterize differences in growth and photosynthetic response to supraoptimal day and night temperatures across a diverse taxonomic range of Salvia . Materials and Methods Eight Salvia taxa were selected to represent a cross

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Lu Zhang, Xiuming Hao, Yonggeng Li, and Gaoming Jiang

temperature set points (ST) and actual temperatures (AT) in the four growth chambers for temperature integration treatments with low pre-night temperature to achieve the same daily (24 h) average temperature of 19.4 °C from May to Oct. 2008. z Air temperature

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Yin-Tung Wang

PPF with a 12-h photoperiod. Ninety percent of the irradiance was provided by cool-white fluorescent tubes and 10% was from incandescent bulbs. There was no barrier between the light source and plants. Treatments were day/night temperatures being

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Meriam Karlsson

The growth of Primula vulgaris Huds. `Dania Lemon Yellow' and `Blue Danova' was evaluated for plants grown at day/night temperature differences of 9, 3, 0, –3 or –9°C. The day temperature was maintained for the duration of the 16-hour photoperiod and the day and night temperatures were selected to provide an average daily temperature of 16°C. The plants were grown at the specific temperatures starting 8 weeks from seeding until flowering. Total daily irradiance was 12 mol·d–1·m–2. Time for visible flower bud, flower color and first open flower was recorded. Plant height and flower bud number were determined at the termination of the experiment. `Dania Lemon Yellow' plants grown with a positive or negative difference of 9°C were significantly (P < 0.05) later in reaching a visible bud stage. There were no differences however, in the number of days required for flower color or first open flower for `Dania Lemon Yellow'. Plants of `Blue Danova' showed a significant difference only in the number of days required for flowering. The plants grown with a positive or zero difference between day and night required on average 2 more days to reach the stage of first open flower. There were no significant differences in plant height or flower bud number in `Dania Lemon Yellow' or `Blue Danova'.

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Meriam Karlsson and Jeffrey Werner

The growth of Cyclamen persicum Mill. `Laser Scarlet' and `Sierra Scarlet' was evaluated for plants grown at day/night temperature differences of +9, +3, 0, –3 or –9°C. The day temperature was maintained for the duration of the 16-hr photoperiod and the day and night temperatures were selected to provide an average daily temperature of 16°C. The plants were grown at the specific temperatures starting 15 weeks from seeding until flowering. Total daily irradiance was 10 mol/day per m2. There was no significant difference in time to flower for plants of `Laser' (115 10.3 days from transplant). Flower buds appeared earlier above the foliage for `Sierra' plants grown at negative differences of 3 or 9°C (113 11.4 days) compared to plants grown at constant 16C (124 9.7 days). At flowering, plants grown with a positive difference of 9°C were significantly taller (22 1.9 cm for `Laser' and 24 2.0 cm for `Sierra') than the plants at 16C (19 1.9 cm for `Laser' and 21 2.1 cm for `Sierra'). Plants of `Laser' grown at +3C difference were also taller (21 2.1 cm) than the control plants at 16°C. Plant dry weight was larger for plants of both `Laser' and `Sierra' grown with +9°C. There were no differences in flower number or flower size among plants within each cultivar grown at the different temperature conditions.

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Matthew G. Blanchard and Erik S. Runkle

In many plant species, stem elongation is influenced by the difference between the DIF ( Myster and Moe, 1995 ). Stem elongation is promoted when the day temperature is higher than the night temperature (+DIF) and suppressed when the day temperature

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Stephanie S. Ningen, Janet C. Cole, and Kenneth E. Conway

Effect of night temperatures on the severity of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. on Euonymus fortunei (Turcz.) Hand.-Mazz. rooted cuttings of `Emerald Gaiety', `Canadale Gold', and `Emerald 'n Gold' was investigated. Uniform cuttings were exposed to day temperatures of 35.3 °C and night temperatures of 19.3 °C or 28.6 °C in growth chambers. Plants exposed to a 28.6 °C night temperature had higher disease ratings than those exposed to a 19.3 °C night temperature. `Emerald Gaiety' was damaged least by C. gloeosporioides compared to `Canadale Gold' and `Emerald 'n Gold'. Disease ratings on all cultivars increased linearly over the 6-week experimental period.

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Mary M. Peet and Michael Bartholemew

Lycopersicon esculentum Mill. `Laura' plants were grown in the North Carolina State Univ. phytotron at 26C day temperature and 18, 22, 24, or 26C night temperatures to determine the effects of night temperature on pollen characteristics, growth, fruit set, and early fruit growth. Total and percentage normal pollen grains were higher in plants grown at night temperatures of 18 and 22C than at 24 and 26C, but germination was highest in pollen produced at 26C. Seed content was rated higher on the plants grown at 18C night temperatures than in any of the other treatments. Numbers of flowers and fruit on the first cluster were lower in the 26C night treatment than in the other night temperature treatments. Plant height was greatest but total shoot dry mass was lowest in the 22C night temperature treatments. Fruit fresh mass increased with night temperature, reflecting more rapid development, but the experiment was not continued to fruit maturity, so the effect of night temperature on final fruit size and total plant production could not be determined. Night temperatures of 26C reduced fruit number and percentage fruit set only slightly at a day temperature of 26C, even though these temperatures were above optimal for pollen production and seed formation. To separate temperature effects on pollen from direct or developmental effects on female reproductive structures, pollen was collected from plants in the four night temperature treatments and applied to stigmas of a male-sterile cultivar kept at 24-18C minimum temperatures in adjacent greenhouses. In the greenhouse-grown male sterile plants, no consistent effects of night temperature treatment given the pollen could be seen in fruit set, fruit mass, seed content (either on a rating or seed count basis), seedling germination, or seedling dry mass.