scholarly journals Effects of Air Temperature Regimes on Physiological Disorders and Floral Development of Tomato Seedlings Grown under Continuous Light

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1304-1306 ◽  
Author(s):  
Katsumi Ohyama ◽  
Yoshitaka Omura ◽  
Toyoki Kozai
Keyword(s):  
Air Temperature ◽  
Floral Development ◽  
Continuous Light ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Tomato Seedlings ◽  
Physiological Disorders ◽  
Air Temperatures ◽  
Temperature Regimes ◽  
Leaf Chlorosis

Providing continuous light (24-h photoperiod) at a relatively low photosynthetic photon flux (PPF) is one possible way to reduce both initial and operational costs for lighting and cooling during transplant production with an artificial light. However, physiological disorders (i.e., chlorosis and necrosis) are often observed in several species under continuous light with a constant temperature. The objective of this study was to find an effective air-temperature regime under the continuous light to avoid such physiological disorders, and simultaneously enhance floral development, using tomato [Lycopersicon esculentum Mill.] as a model. The seedlings with fully expanded cotyledons were grown for 15 d at a PPF of 150 μmol·m–2·s–1, a relative humidity of 70%, and a CO2 concentration of about 380 μmol·mol–1 (atmospheric standard). Leaf chlorosis was observed when the air temperature was constant regardless of average air temperature (16, 22,or 28 °C). Neither leaf chlorosis nor necrosis was observed when the air temperatures were alternated [periods of high (28 °C) and low (16 °C) air temperatures of 16/8, 12/12, and 8/16 h·d–1]. Faster floral development was observed in the seedlings grown at lower average air temperatures. These results indicated that physiological disorders of tomato seedlings grown under continuous light could be avoided, and at the same time floral development could be enhanced, by lowering the average air temperature through modification of the periods of high and low air temperatures.

scholarly journals The Combined Conditions of Photoperiod, Light Intensity, and Air Temperature Control the Growth and Development of Tomato and Red Pepper Seedlings in a Closed Transplant Production System

2020 ◽  
Vol 12 (23) ◽  
pp. 9939
Author(s):  
Hyunseung Hwang ◽  
Sewoong An ◽  
Minh Duy Pham ◽  
Meiyan Cui ◽  
Changhoo Chun
Keyword(s):  
Plant Growth ◽  
Air Temperature ◽  
Production System ◽  
Dry Weight ◽  
Red Pepper ◽  
Photon Flux ◽  
Limiting Factor ◽  
Factors Affecting ◽  
Tomato Seedlings ◽  
Air Temperatures

Understanding environmental factors is essential to maximizing the biomass production of plants. There have been many studies on the effects of the photosynthetic photon flux (PPF), photoperiod and air temperature as separate factors affecting plants, including under a closed transplant production system (CTPS). However, few studies have investigated the combined effects of these factors on plant growth. Germinated tomato and red pepper seedlings were transferred to three different photoperiods with five different photosynthetic photon fluxes (PPFs) at an air temperature of 25/20 °C to investigate plant growth under a different daily light integral (DLI). Three different air temperatures, 23/20, 25/20, and 27/20 °C (photo/dark periods), with five different PPFs were used to examine plant growth under different DIFs (difference between the day and night temperature). Increasing the DLI from 4.32 to 21.60 mol·m−2·d−1, either by increasing the photoperiod or PPF, improved the growth of seedlings in both cultivars. However, when comparing treatments that provided the same DLI, tomato seedlings had s significantly higher growth when grown under longer photoperiods and s lower PPF. Even in higher DLI conditions, reduced growth due to higher PPF indicated that excessive light energy was a limiting factor. At 23 and 25 °C, tomato seedlings showed similar correlation curves between growth and PPF. However, at the higher temperature of 27 °C, while the slope of the curve at low PPFs was similar to that of the curves at lower temperatures, the slope at high PPFs was flatter. On the other hand, red pepper seedlings displayed the same correlation curve between growth and PPF at all tested temperatures, and red pepper plants accumulated more dry weight even at higher temperatures. These results suggested that the combination effect was more useful to observe these overall tendencies, especially in reacting to a second factor. This will provide us with more information and a deeper understanding of plant characteristics and how they will behave under changing environments.

scholarly journals Potential Use of a 24-Hour Photoperiod (Continuous Light) with Alternating Air Temperature for Production of Tomato Plug Transplants in a Closed System

HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 374-377 ◽  
Author(s):  
Katsumi Ohyama ◽  
Koji Manabe ◽  
Yoshitaka Omura ◽  
Toyoki Kozai ◽  
Chieri Kubota
Keyword(s):  
Air Temperature ◽  
Closed System ◽  
Energy Use ◽  
Electric Energy ◽  
Continuous Light ◽  
Dry Weight ◽  
Photon Flux ◽  
Air Temperatures ◽  
Use Efficiency ◽  
Potential Use

To evaluate the potential use of a 24-hour photoperiod for transplant production in a closed system, tomato (Lycopersicon esculentum Mill.) plug transplants were grown for 17 days either under a 24-hour photoperiod with a photosynthetic photon flux (PPF) of 200 μmol·m-2·s-1 or under a 16-hour photoperiod with a PPF of 300 μmol·m-2·s-1, resulting in the same daily integrated PPF (17.3 mol·m-2). Air temperatures were alternated between 28 °C during the first 16 hours and 16 °C for the subsequent 8 hours of each day. Fresh weight, dry weight and leaf area were 41%, 25%, and 64% greater, respectively, under the 24-hour photoperiod than under the 16-hour photoperiod. Physiological disorders (e.g., chlorosis and/or necrosis) were not observed under the 24-hour photoperiod, probably due to the alternating air temperature. Floral development of plants originating from both treatments did not differ significantly. Electric energy use efficiency of the closed system was 9% greater under the 24-hour photoperiod than under the 16-hour photoperiod. These results suggest that using a 24-hour photoperiod with relatively low PPF can reduce both initial and operational costs for transplant production in a closed system due to the reduction in the number of lamps.

scholarly journals Floral Development and Bolting of Spinach as Affected by Photoperiod and Integrated Photosynthetic Photon Flux During Transplant Production

HortScience ◽  
2001 ◽  
Vol 36 (5) ◽  
pp. 889-892 ◽  
Author(s):  
Changhoo Chun ◽  
Machiko Tominaga ◽  
Toyoki Kozai
Keyword(s):  
Air Temperature ◽  
Vegetative Growth ◽  
Floral Development ◽  
Spinacia Oleracea ◽  
Short Photoperiod ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Flower Stalk ◽  
Stalk Length

We recently showed that spinach (Spinacia oleracea L.) transplants produced under a short photoperiod and low air temperature were characterized by a delay of bolting and short flower-stalk length at harvest (Chun et al., 2000a). The present study was conducted to determine whether these changes are caused by the short photoperiod itself or by the lower integrated photosynthetic photon flux (IPPF). Shoot and root dry weights of transplants increased significantly with increasing IPPF, but were not affected by a change in the photoperiod. However, the floral development indices of transplants were significantly greater under a 16-than under a 10- or 13-hours/day photoperiod, but were not affected by a change in IPPF. The percentage of bolted plants 3 days after transplanting (DAT) increased significantly with increasing photoperiod (from 0% at 10 hours/day to more than 85% at 16 hours/day). Flower-stalk length increased with increasing photoperiod (e.g., at 14 DAT, from 15 mm at the shorter photoperiods to 80 mm at 16 hours/day), but was not affected by a change in IPPF. These results show that the delay of bolting that occurs when the photoperiod is reduced during transplant production is due to the delay of floral development and not to retarded vegetative growth as a result of reduced IPPF.

scholarly journals 510 PB 260 COMPARISON OF FIELD AND SHADEHOUSE MICROCLIMATE FACTORS RELATED TO EVAPORATION AND CROP TRANSPIRATION

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 504e-504
Author(s):  
Robert H. Stamps
Keyword(s):  
Photon Flux ◽  
Pressure Gradients ◽  
Crop Canopy ◽  
Photosynthetic Photon Flux ◽  
Water Losses ◽  
Air Temperatures ◽  
Plant Water Use ◽  
Adjacent Field ◽  
Rumohra Adiantiformis ◽  
Incoming Light

Microenvironmental conditions in a shadehouse covered with shade fabric designed to exclude 70% of incoming light were monitored and compared to those in an adjacent field to quantify differences related to plant water use. Radiant flux density and photosynthetic, photon flux inside the shadehouse varied seasonally between about 18% to 28% of outside values. During the day, leaf and air temperatures around the crop canopy were generally lower and relative humidities higher inside the shadehouse than outside. Leaf-to-air vapor pressure gradients inside the shadehouse averaged about half those outside. Wind run inside was <10% of wind run outside. Differences between reference ET (ETo) values, calculated using Penman's equation), inside and outside the shadehouse were greatest during summer months. Outside evaporatory pan (Epan) water losses ranged from 205 mm in July to 95 mm in Nov. For the same months, Epan losses inside were about 80% lower. Monthly ETactual, as determined for Rumohra adiantiformis growing in lysimeters in the shadehouse, ranged from around 40% to 80% of inside Eo.

scholarly journals Analyses of the Zagreb Grič observatory air temperatures indices for the period 1881 to 2017

2018 ◽  
pp. 67-85 ◽  
Author(s):  
Ognjen Bonacci ◽  
Tanja Roje Bonacci
Keyword(s):  
Time Series ◽  
Air Temperature ◽  
Partial Sums ◽  
Daily Maximum ◽  
Absolute Maximum ◽  
Absolute Minimum ◽  
Air Temperatures ◽  
Temperature Regimes ◽  
Urban Heat ◽  
Maximum Temperatures

The paper studies time series of characteristic (minimum, mean, and maximum) daily, monthly, and yearly air temperatures measured at the Zagreb Grič Observatory in the period from 1 Jan. 1881 to 31 Dec. 2017. The following five air temperatures indices (ATI) are analysed: (1) absolute minimum yearly, monthly, and daily; (2) mean yearly, monthly, and daily minimum; (3) average mean yearly, monthly, and daily; (4) mean yearly, monthly, and daily maximum; (5) absolute maximum yearly, monthly, and daily. Methods of Rescaled Adjusted Partial Sums (RAPS), regression and correlation analyses, F-tests, and t-tests are used in order to describe changes in air temperature regimes over 137 years. Using the RAPS method the five analysed yearly ATI time series durations of 137 years were divided into two sub-periods. The analyses made in this paper showed that warming of minimum air temperatures started in 1970, mean air temperatures in 1988, and maximum air temperatures in 1998. Results of t-tests show an extreme statistically significant jump in the average air-temperature values in the second (recent time) sub-periods. Results of the t-tests of monthly temperatures show statistically significant differences between practically all five pairs (except in two cases) of analysed monthly ATI subseries for the period from January to August. From September to December the differences for most of pairs (except in six cases) of the analysed monthly ATI subseries are not statistically significant. It can be concluded that the urban heat island influenced the increase in recent temperatures more strongly than global warming. It seems that urbanisation firstly and chiefly influenced the minimum temperatures, as well as that Zagreb’s urbanisation had a bigger impact on minimum temperatures than on maximums. Increasing trend in time series of maximum temperatures started 20 years later.

scholarly journals (56) Transpiration and Photosynthesis of Grafted Watermelon Transplants as Affected by Environmental Factors during Graft Union Formation

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 996D-996
Author(s):  
Sung Kyeom Kim ◽  
Duk Jun Yu ◽  
Ro Na Bae ◽  
Hee Jae Lee ◽  
Changhoo Chun
Keyword(s):  
Environmental Factors ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Vapor Pressure Deficit ◽  
Photon Flux ◽  
Union Formation ◽  
Graft Union ◽  
Yield And Quality ◽  
Air Temperatures ◽  
Grafted Transplants

Grafted transplants are widely used for watermelon culture in Korea mainly to reduce the yield and quality losses caused by soil-borne diseases. It is normal practice to cure the grafted transplants under high relative humidity (RH) and low photosynthetic photon flux (PPF) conditions for a few days after grafting to prevent the wilting of the transplants. Transpiration rate (TR) and net photosynthetic rate (NPR), however, could be suppressed under those environmental conditions. In the present study, TR and NPR of the grafted watermelon transplants were compared during graft union formation under 18 environmental conditions combining two air temperatures (20 and 28 °C), three RHs (60%, 80%, and 100%), and three PPF s (0, 100, and 200 μmol·m-2·s-1). Percentages of graft union formation and survival were also evaluated. TR and NPR dramatically decreased just after grafting but slowly recovered 2 to 3 days after grafting at 28 °C. The recovery was clearer at higher PPF and lower RH. On the other hand, the recovery of TR and NPR was not observed in 7 days after grafting at 20 °C. Differences in TR and NPR affected by RH were nonsignificant. Percentage of graft union formation was 98% when air temperature, RH, and PPF were 28 °C, 100%, and 100 μmol·m-2·s-1, respectively, which was the highest among all the treatments. Percentage of survival was over 90% when air temperature was 28 °C and RH was higher than 80% (when vapor pressure deficit was lower than 0.76 kPa). In addition, higher PPF enhanced TR and NPR and promoted rooting and subsequent growth of grafted transplants. Results suggest that the acclimation process for grafted watermelon transplants can be omitted by properly manipulating environmental factors during graft union formation.

scholarly journals Branching of Chrysanthemum Cultivars Varies with Season, Temperature, and Photosynthetic Photon Flux

HortScience ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 74-78 ◽  
Author(s):  
Richard K. Schoellhorn ◽  
James E. Barrett ◽  
Terril A. Nell
Keyword(s):  
Linear Relationship ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Root Zone ◽  
Lateral Branch ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Lateral Shoot ◽  
Commercial Cultivars ◽  
Lateral Branches

Effects of photosynthetic photon flux (PPF) and temperature on quantitative axillary budbreak and elongation of pinched chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] plants were studied in three experiments. In Expt. 1, 12 commercial cultivars were compared under fall and spring environmental conditions. Spring increases in lateral shoot counts were attributable to increased PPF and air temperature. Cultivars varied from 0 to 12 lateral branches per pinched plant and by as much as 60% between seasons. There was a linear relationship between lateral branches >5 cm at 3 weeks after pinching and final branch count (y = 0.407 + 0.914(x), r2 = 0.92). In Expt. 2, air was at 20 or 25C and the root zone was maintained at 5, 0, or –5C relative to air temperature. With air at 20C, lateral branch counts (3 weeks after pinch) declined by ≤50% with the medium at 15C relative to 25C. At 25C, lateral branch count was lower with medium at 30C than at 20C. Cultivars differed in their response to the treatments. Experiment 3 compared the interactions among temperature, PPF, and cultivar on lateral branch count. Depending on cultivar, the count increased the higher the PPF between 400 and 1400 μmol·m–2·s–1. Air temperature had no effect on lateral branch count. PPF had a stronger effect on lateral branch count than air temperature, and cultivars differed in their response.

scholarly journals Effects of Three Hotcap Designs on Temperature and Tomato Transplant Development

HortScience ◽  
1993 ◽  
Vol 28 (9) ◽  
pp. 878-881
Author(s):  
G.E. Welbaum
Keyword(s):  
Solar Energy ◽  
Lycopersicon Esculentum ◽  
Growth Chamber ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Ripe Fruit ◽  
Air Temperatures ◽  
Cloudy Weather ◽  
Soil Temperatures ◽  
Opaque Plastic

Hotcaps are covers used to protect individual plants from suboptimal temperatures. Temperature, solar energy, photosynthetic photon flux (PPF), and tomato (Lycopersicon esculentum Mill.) transplant development were compared for three hotcap designs: 3.8-liter, opaque plastic jugs (PJs); 24-cm-tall wax paper (WP); and Wall-O-Water water-filled plastic teepees (PTs). The average solar energy inside the hotcaps was 57.3%, 67.6%, and 28.9% of full sun at midday and PPF was 44.7%, 49.7%, and 43.8% of full sun at midday for WP, PJs, and PTs, respectively. The rate of temperature decline in a growth chamber was fastest for PJs and slowest for PTs. In the field, air and soil temperatures inside hotcaps were higher than ambient during sunny periods and essentially the same during cloudy weather. The overall mean and mean maximum daily soil and air temperatures for all hotcaps were higher than ambient. PTs had the highest minimum daily soil and air temperatures—2.0 and 1.9C above ambient, respectively. The meantime to first ripe fruit was reduced by 10.7 days for PTs, 6.7 days for WP, and increased by 5 days for PJs compared to noncovered plants. Plants grown under hotcaps weighed less and produced fewer fruit on the first cluster. PJs could not maintain night air temperatures above ambient and were not effective hotcaps.

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