scholarly journals GAS EXCHANGE RATES BY A STAND OF SOYBEANS GROWN IN A TIGHTLY SEALED CHAMBER

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1151c-1151
Author(s):  
R.M. Wheeler ◽  
K.A. Corey ◽  
J.C. Sager ◽  
C. L. Mackowiak ◽  
W.M. Knott
Keyword(s):  
Glycine Max ◽  
Life Cycle ◽  
Exchange Rates ◽  
Dark Period ◽  
Photon Flux ◽  
Canopy Closure ◽  
Photosynthetic Photon Flux ◽  
Respiration Rates ◽  
Soybean Plants ◽  
Photosynthesis And Respiration

Soybean plants [Glycine max (L.) Merr. cv. McCall] were grown from seed to harvest (90 days) in NASA's Biomass Production Chamber. The chamber provides approximately 20 m2 of growing area with an atmospheric volume of 113 m3. Photosynthesis and respiration rates of the stand were tracked by monitoring CO2 increase during the 12-h dark period and the subsequent drawdown to controlled set point (1000 ppm) when the lamps were turned on each day. Stand photosynthesis [under 875 μmol m-2 s-1 photosynthetic photon flux (PPF)] peaked at 35 μmol m-2 s-1 at 30 to 35 days after planting (DAP) and averaged 22 μmol m-2 s-1 throughout the life cycle. Dark period respiration peaked near 8 μmol m-2 s-1 at 30 to 35 DAP and averaged nearly 5 μmol m-2 s-1 throughout the life cycle. Prior to full canopy closure near 30 DAP, the light compensation point (LCP) for stand photosynthesis was lass than 100 μmol m-2 s-1 PPF; by 54 DAP the LCP had increasad to 175 μmol m-2 s-1. Stand transpiration rates peaked at 8.2 L m-2 day-1 at 40 to 45 DAP and averaged 4.3 L m-2 day-1 throughout growth.

CARBON DIOXIDE EXCHANGE RATES OF FRUITING SOYBEAN PLANTS EXPOSED TO OZONE AND SULPHUR DIOXIDE SINGLY OR IN COMBINATION

1984 ◽  
Vol 64 (1) ◽  
pp. 69-75 ◽  
Author(s):  
N. M. LE SUEUR-BRYMER ◽  
D. P. ORMROD
Keyword(s):  
Carbon Dioxide ◽  
Glycine Max ◽  
Exchange Rates ◽  
Sulphur Dioxide ◽  
Net Photosynthesis ◽  
Exposure Period ◽  
Carbon Dioxide Exchange ◽  
Continuous Stirred Tank Reactor ◽  
Glycine Max L ◽  
Soybean Plants

Carbon dioxide exchange rates (CER) of intact soybean (Glycine max (L.) Merr.) plants at the fruiting stage were measured in continuous stirred tank reactor (CSTR) chambers. Plants were exposed to clean air, 67 ppb ozone (O3), 300 ppb sulphur dioxide (SO2), or 67 ppb O3 plus 300 ppb SO2 for 7.5 h∙day−1 for 5 days. Carbon dioxide exchange rates were measured hourly during the last 6 h of each exposure period and decreased progressively during the first period of exposure to O3 plus SO2, dropping in hour 6 to 42% of the hour 1 rate, and to a lesser extent in the second daily exposure when the corresponding decline was to 70%. There was a declining trend in CER of SO2-treated but not O3-treated plants with increasing number of days of exposure. Carbon dioxide exchange rates of all plants generally peaked and declined during each exposure period.Key words: Air pollution, net photosynthesis, mixtures, Glycine max

Response of Soybeans (Glycine max) and Four Broadleaf Weeds to Reduced Irradiance

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 570-574 ◽  
Author(s):  
Edward W. Stoller ◽  
Randy A. Myers
Keyword(s):  
Glycine Max ◽  
Leaf Area ◽  
Leaf Respiration ◽  
Common Lambsquarters ◽  
Eastern Black Nightshade ◽  
Black Nightshade ◽  
Respiration Rates ◽  
Growth Irradiance ◽  
Soybean Plants ◽  
Root:Shoot Ratios

Experiments were conducted to determine adaptation characteristics to reduced irradiance of velvetleaf, common lambsquarters, eastern black nightshade, tumble pigweed, and soybean. Plants were grown to the 5- to 8-leaf stage in the greenhouse at ambient radiation (850 μE·m–2·s–1), and 26 and 13% of ambient radiation. Tumble pigweed, a C4plant, had the highest light-saturated photosynthetic rates at all growth irradiances, while common lambsquarters had the highest rates of the four C3species. All species adjusted to reduced irradiance by decreasing light-saturated photosynthesis, leaf respiration rates, root:shoot ratios, and leaf densities, while increasing leaf area ratios (LAR)3. As growth irradiance was reduced, support tissues (roots, stems, and petioles):leaf ratios did not change for common lambsquarters or velvetleaf, increased for soybean, and decreased for eastern black nightshade and tumble pigweed, indicating superior adaptation of the latter two species for efficient light harvesting at reduced growth irradiances. Of these five species, eastern black nightshade had the lowest respiration rate, the highest LAR, and the lowest support:leaf ratio for optimum adaptation to shaded environments.

scholarly journals 506 PB 248 DETERMINING THE EFFECT OF CLOUD CONDITIONS ON THE VARIATION IN DAYLENGTH PERCEIVED BY PLANTS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 504a-504
Author(s):  
James E. Faust ◽  
Royal D. Heins
Keyword(s):  
Dark Period ◽  
Extended Period ◽  
Canopy Height ◽  
Photon Flux ◽  
Flower Initiation ◽  
Plant Canopy ◽  
Maximum Difference ◽  
Photosynthetic Photon Flux ◽  
Naval Observatory ◽  
Actual Difference

Quantum sensors were placed at plant canopy height inside and outside a glass greenhouse. Photosynthetic photon flux (PPF) was measured during September for a 3-hour period near sunrise and sunset, which were determined from US Naval Observatory Circular #171. Under clear skies, the PPF at the canopy exceeded 0.25 μmol·m-2·s-1 for nearly 20 minutes before sunrise through 20 minutes after sunset. Under heavy overcast, the duration was only 5 minutes before sunrise through 5 minutes after sunset. The PPF at the canopy reached 0.25 μmol·m-2·s-1 approximately 12 minutes later in the morning and 12 minutes earlier in the evening than it did outside the greenhouse. The length of the dark period perceived by plants in a greenhouse on September 21st (assuming plants perceive light at 0.25 μmol·m-2·s-1) can range from 11:37 (hr:min) during cloudy conditions to 11:15 during clear ones, a difference of 22 minutes. At 43°N latitude, the maximum difference in date of flower initiation because of an extended period of heavily overcast versus clear weather on a crop such as poinsettias would be one week since the night length during September increases by 3 minutes per day. The actual difference from year to year is probably less because a seven-day duration of heavily overcast weather is unlikely.

scholarly journals Transplant Quality as Affected by Temperature, Light Intensity, and Photoperiod during Storage

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 481C-481
Author(s):  
C. Kubota ◽  
S. Seiyama ◽  
K. Sakami ◽  
T. Kozai
Keyword(s):  
Dark Period ◽  
Solanum Melongena ◽  
Dry Weight ◽  
Continuous Illumination ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Successful Management ◽  
Percent Survival ◽  
Different Temperatures ◽  
Plug Seedling

Storage techniques to hold the seedlings for several weeks prior to shipping/transplanting have been required for the successful management in plug seedling production. During storage, it is required to suppress growth and development of the seedlings as well as to preserve their transplant quality. Illumination during storage has been shown to be important for storage of high-quality transplants. In the present experiments, eggplant (Solanum melongena L.) plug seedlings, which were ready for transplanting after 3 weeks of growth under 28/20C photo-/dark period temperature, 330 μmol·m–2·s–1 photosynthetic photon flux (PPF), and 16-hr photoperiod per day, were stored for 3 to 4 weeks under combinations of different temperatures, PPF, and photoperiods. Storage air temperature affected elongation of the seedlings during 3 weeks of storage. Continuous illumination at a PPF close to the light compensation point maintained dry weight of the seedlings unchanged during storage and kept the high percent survival after storage. Storage in darkness reduced the dry weight during storage and, thus, the percent survival after storage. PPF and photoperiod were shown to be important factors in the preservation of transplant quality and suppression of growth of the seedlings during storage.

scholarly journals Elucidating the effects of TiO2 nanoparticles on the toxicity and accumulation of Cu in soybean plants (Glycine max L.)

2021 ◽  
Vol 219 ◽  
pp. 112312
Author(s):  
Yinlong Xiao ◽  
Ying Du ◽  
Yue Xiao ◽  
Xiaohong Zhang ◽  
Jun Wu ◽  
...  
Keyword(s):  
Glycine Max ◽  
Tio2 Nanoparticles ◽  
Glycine Max L ◽  
Soybean Plants
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