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Temperature is one of the main factors that affects the growth pattern of Gerbera hybrida, which shows vast variation in morphology and stress adaptation among cultivars. However, little is known about temperature responses of plant growth among different cultivars. In this study, four cultivars were planted in different growth temperatures to investigate the effect of temperature on plant growth of Gerbera hybrida during their vegetative growth. Results showed that the optimum growth temperature of the four cultivars was 20 °C, of which plant height, root length, biomass accumulation, leaf area, and photosynthetic rate were enhanced significantly. Different cultivars showed diverse temperature adaptation ranges, which were related with their genetic background, and the temperature adaptability of cultivar Autumn was the best among the four cultivars. Temperature also had significant effects on photosynthetic rate, which was the main factor shaping plant growth. Our research provides the basic guidance for the growth temperature control in the cultivation of Gerbera hybrida.

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The successful germination of triploid watermelon seeds depends largely upon three factors; moisture control, planting depth, and temperature control. The planting medium must be moistened until it is humid, but not wet enough for free water to be squeezed from a handful. This level of humidity must be maintained until germination is complete. The planting depth should be 1.25 to 2.5 cm. This reduces the number of seeds that “push” themselves from the medium and also facilitates correct moisture maintenance. Seeded trays should be placed in a germination room and held 48–72 hours at a temperature of 30 to 32 °C and a relative humidity of 90% to 95% until germination begins. When germination is complete, the plants can be watered normally.

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Little is known about the effect of growth temperature on Aster (Compositae, Asteraceae) flower development. In this study, we report on this effect for two aster lines, `Suntana' and `Sungal'. Growth temperature had a dramatic effect on the duration of flower development, ranging from 22 days for plants growing at 29 °C up to 32 days for plants grown at 17 °C. Flower longevity was ≈40% shorter under the higher temperature for both lines. Growth temperature also affected flowerhead form: `Suntana' flowerhead diameter was 20% larger at 17 °C than at 29 °C. The number of `Sungal' florets per flowerhead was four times greater at the lower temperature. Shading (30%) under temperature-controlled conditions had no effect on any of the parameters measured. For plants grown outdoors, our results suggest that shading plants may increase quality by reducing the growth temperature.

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Abstract

‘Atlas’ and ‘Monika’ alstroemeria (Alstroemeria hybrida L.) were grown in cooled (12 to 16C) and noncooled (15 to 18C) gravel substrate in four temperature-controlled greenhouse compartments having mean day/night air temperatures of: 20/14, 20/13, 22/13, and 24/14C. Total flower production of ‘Atlas’ in all compartments was 1.6 times greater than for ‘Monika’. The greatest production of ‘Atlas’ occurred with 20C average daytime air temperatures combined with root substrate temperatures 12C to 14C, which favored year-round production. Warmer day temperatures tended to improve flower grade and stem length of ‘Monika’; however, the higher yield in cooler air temperatures outweighed the contributions of warmer air temperatures to quality. ‘Atlas’ stems were significantly longer and of better quality than ‘Monika’ in all temperature regimes.

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Abstract

Studies on winter desiccation of broadleaved evergreens have raised the question of low temperature impedance of water movement in roots and stems. Temperature control of a section of stem can be readily accomplished by the use of cooling collars. Johnson (3), Handley (1), and Zimmerman (6) have brought about wilting of the leaves of various tree species by cooling parts of the stem to near or below the tissue freezing point. Presumably, the wilting was caused by restriction of water flow through the cooled section of stems. The wilted foliage recovered after the stem temperatures were allowed to rise, but no attempt has been reported to measure the minimum temperature at which water started to flow through the stem after freezing. To obtain information on this latter question was the primary objective of the study reported here.

Open Access

Abstract

Ficus benjamina was held in light-and-temperature-controlled chambers for 12 weeks under 3 light sources of 20 μE m−2s−1 incandescent (INC) lamps, 20 μE m−2s−1 Cool White fluorescent (CWF) lamps, or 10 μE m−2s−1 INC + 10 μE m−2s−1 CWF light combination totaling 20 μE m−2s−1 photosynthetically active radiation (PAR). Plants also received 4 light durations (6, 12, 18, or 24 hr/day). Growth index was greater for plants held under INC. When plants were held under the light combination, leaf drop was reduced and plant grade was improved. Dry weight and plant grade increased and leaf drop decreased when plants were lighted for 24 hr/day. Chlorophyll content decreased under the light sources in the following order: CWF> light combination >INC.

Open Access

Abstract

Premature ripening, a physiological disorder of ‘Bartlett’ pears, was induced experimentally by use of temperature controlled limb cages. Exposure to 65° day and 45° F night temperatures for 3-31 days prior to harvest caused an early acceleration in ethylene production and occurrence of the climacteric rise in respiration. These changes were accompanied by fruit softening, increases in soluble pectin and protein N, a more rapid decline in malic acid as well as a decrease in the rate of citric acid accumulation. Treatments with gibberellic acid (GA3), 100 ppm, and succinic acid 2,2-dimethyl hydrazide (Alar), 1000 ppm, counteracted the effect of cool temperature exposure and retarded premature ripening. The disorder did not develop in fruit maintained at 75° day and 60° night temperatures during the experiment.

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Abstract

The effects of high (86°F) and low (68°F) day temperature, and of high (2,500 to 5,000 ft-c) and low (500 to 1,200 ft-c) light intensity, on the coloration of ‘Cardinal’ and ‘Pinot noir’ grapes grown in sunlit, temperature-controlled rooms during the ripening period were investigated. Night temperature (7 PM to 7 AM) was 59°F in all treatments.

Low day temperature significantly increased the level of anthocyanin pigments in the skins of both cultivars at both high and low light intensity. Anthocyanin synthesis was almost completely inhibited in the skins of ‘Cardinal’ berries that had average daytime temperatures between 91 and 95°F.

Low light intensity greatly reduced coloration of ‘Pinot noir’ grapes at both low and high day temperatures but decreased the level of pigments in grapes grown at 86°F. It either increased or had little effect on fruit coloration of ‘Cardinal’ grapes grown at 68°F.

Open Access

Lycoris radiata has beautiful bright-red flowers with both medicinal and ornamental value. However, the mechanisms underlying an unusual characteristic of Lycoris radiata, flowering without leaves, remain unclear. In this study, climatic influences, biomass composition, and yearly variations in bulb contents across eight developmental stages of L. radiata were analyzed. Thus, L. radiata summer dormancy was investigated in three dimensions: climate-associated phenology, biomass distribution characteristics, and physiologic bulb changes. The results showed that dormancy was most strongly affected by high ambient temperature, followed by scape development, flowering, leafing out, vigorous leaf growth, flower bud differentiation, flower bud predifferentiation, and leaf maturation. Biomass allocation, bulb contents, oxidoreductase activity, and root activity fluctuated significantly in L. radiata among developmental stages. Relative bulb dry weight was greatest during the dormant period (95.95% of total dry weight) and lowest during vigorous leaf growth (November–December). Root biomass was also significantly greater during dormancy than during flowering, leaf maturation, and flower bud differentiation. Only root biomass during vigorous leaf growth was greater than root biomass during dormancy. However, in dormant bulbs, soluble sugar content, soluble protein content, root activity, superoxide dismutase (SOD) activity, and peroxidase (POD) activity decreased. Thus, summer dormancy in L. radiata only constitutes a morphologic dormancy of the aboveground plant; the bulb and root remain physiologically active. The results suggest that L. radiata is sensitive to both ambient temperature and light, and that summer dormancy is triggered by the synergistic stimulation of these two factors. Although temperature controls dormancy, it plays only a limited regulatory role during the L. radiata flowering period. Thus, it is difficult to induce flowering or regulate annual flowering in this species through temperature control alone.

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Modified Atmosphere Packaging (MAP) in combination with temperature control were investigated for qualify enhancement of sweet cherries (Prunus avium L.). `Bing', `Lambert' and `Rainier' cherries (1 kg/pkg/rep) were wrapped in 1 of 3 different MAP films (5,303; 8,900 and 11,286 cc/sq M/24 hrs of O2 and stored at 0 or 4 C for 3 weeks. Post-storage evaluations included both fruit and stem color, fruit firmness, weight loss, soluble solids, titratable acidity, bruising and pitting valuations, respiration rates and visual assessment. MAP films helped maintain fruit and stem color, and fruit firmness, Whereas weight loss and bruising were reduced. Visual assessment was best with fruit in MAP film packages, There was little change in soluble solids and titratable acidity among fruit in the different MAP films. Control (unwrapped) fruit had considerably higher soluble solids and titratable acidity than wrapped fruit. This difference in soluble solids and titratable acidity between control and MAP fruit was associated with a considerable weight loss in the control fruit. Respiration rates of the fruit varied among the different MAP films and was cuitivar dependent. Fruit stored at 0 C had better quality after 3 weeks of storage than fruit stored at 4 C.

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