The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Kenji Omasa - One of the best experts on this subject based on the ideXlab platform.

  • effects of temperature photosynthetic Photon Flux Density photoperiod and o2 and co2 concentrations on growth rates of the symbiotic dinoflagellate amphidinium sp
    Journal of Applied Phycology, 2008
    Co-Authors: Yoshiaki Kitaya, Masashi Tsuda, L Xiao, A Masuda, Tomoko Ozawa, Kenji Omasa
    Abstract:

    Symbiotic dinoflagellates of the species Amphidinium are expected to be pharmaceutically useful microalgae because they produce antitumor macrolides. A microalgae production system with a large number of cells at a high Density has been developed for the efficient production of macrolide compounds. In the present study, the effects of culture conditions on the cellular growth rate of dinoflagellates were investigated to determine the optimum culture conditions for obtaining high yields of microalgae. Amphidinium species was cultured under conditions with six temperature levels (21–35°C), six levels of photosynthetic Photon Flux Density (15–70 μmol Photons m−2 s−1), three levels of CO2 concentration (0.02–0.1%), and three levels of O2 concentration (0.2–21%). The number of cells cultured in a certain volume of solution was monitored microscopically and the cellular growth rate was expressed as the specific growth rate. The maximum specific growth rate was 0.022 h−1 at a temperature of 26°C and O2 concentration of 5%, and the specific growth rate was saturated at a CO2 concentration of 0.05%, a photosynthetic Photon Flux Density of 35 μmol Photons m−2 s−1 and a photoperiod of 12 h day−1 upon increasing each environmental parameter. The results demonstrate that Amphidinium species can multiply efficiently under conditions of relatively low light intensity and low O2 concentration.

D. J. Yates - One of the best experts on this subject based on the ideXlab platform.

  • seasonal variation in the red far red ratio and Photon Flux Density in an australian sub tropical rainforest
    Agricultural and Forest Meteorology, 1993
    Co-Authors: Matthew H. Turnbull, D. J. Yates
    Abstract:

    The temporal distribution of red light (R, in the range 655-665 nm) and far-red light (FR, in the range 725-735 nm) was measured at 10 min intervals for 1 year at three contrasting sites in a sub-tropical rainforest. It was measured in the understorey beneath a closed canopy, in the middle of a 450 m2 tree-fall gap, and at the transition between the gap and understorey. The red/far-red ratio (R/FR) was calculated from these data. Values of Photon Flux Density (PFD, in the range 400-700 nm) were also determined from the output of the R sensing channel of each sensor. Although a higher overall R/FR ratio was measured in the gap site compared with the understorey and gap-edge sites, R/FR ratios in the gap were at levels which are indicative of canopy shade (between 0.4 and 0.8) for much of the day. No distinct seasonal variation in daily average R/FR ratio was observed in any of the three sites, although day to day variation was marked. Daily average R/FR ratio was generally higher in the gap-edge and gap sites than in the understorey. Daily average PFD in the understorey was below 20 μmol m-2 s-1 for all but 1 day during the year, and below 30 μmol m-2 s-1 for 7 months at the gap-edge site and 3 months in the gap. While daily average PFD also varied from day to day in the gap-edge and gap sites, observations showed considerable seasonal variation during the course of the year.

  • Seasonal variation in the red/far-red ratio and Photon Flux Density in an Australian sub-tropical rainforest
    Agricultural and Forest Meteorology, 1993
    Co-Authors: Matthew H. Turnbull, D. J. Yates
    Abstract:

    The temporal distribution of red light (R, in the range 655-665 nm) and far-red light (FR, in the range 725-735 nm) was measured at 10 min intervals for 1 year at three contrasting sites in a sub-tropical rainforest. It was measured in the understorey beneath a closed canopy, in the middle of a 450 m2 tree-fall gap, and at the transition between the gap and understorey. The red/far-red ratio (R/FR) was calculated from these data. Values of Photon Flux Density (PFD, in the range 400-700 nm) were also determined from the output of the R sensing channel of each sensor. Although a higher overall R/FR ratio was measured in the gap site compared with the understorey and gap-edge sites, R/FR ratios in the gap were at levels which are indicative of canopy shade (between 0.4 and 0.8) for much of the day. No distinct seasonal variation in daily average R/FR ratio was observed in any of the three sites, although day to day variation was marked. Daily average R/FR ratio was generally higher in the gap-edge and gap sites than in the understorey. Daily average PFD in the understorey was below 20 μmol m-2 s-1 for all but 1 day during the year, and below 30 μmol m-2 s-1 for 7 months at the gap-edge site and 3 months in the gap. While daily average PFD also varied from day to day in the gap-edge and gap sites, observations showed considerable seasonal variation during the course of the year.

Charles P. Chirko - One of the best experts on this subject based on the ideXlab platform.

  • influence of direction and distance from trees on wheat yield and photosynthetic Photon Flux Density qp in a paulownia and wheat intercropping system
    Forest Ecology and Management, 1996
    Co-Authors: Charles P. Chirko, Michael A. Gold, Phu V. Nguyen, J P Jiang
    Abstract:

    Abstract A Paulownia -winter wheat intercropping experiment with the object of quantifying photosynthetically active radiation (PAR) and its effect on wheat yield was conducted 60 km south of Zhengzhou (35°N 113°E), Henan Province, PR China, from September 1991 to July 1992 using a tree and crop interface approach. The middle row of three 240 m long rows of 11-year-old trees was studied for its effects on the yield of irrigated and fertilized winter wheat. Photosynthetic Photon Flux Density ( Q p ) was quantified using a split-plot design with four blocks. There were four distance (subplot) treatments (2.5 m, 5 m, 10 m and 20 m) and two direction (main plot) treatments laid out to the east and west of a north-south tree line. Results showed no difference in direction effects but Q p did affect total grain weight ( P = 0.0047) between 2.5 m and 20 m. A regression equation was fit using the mean for each distance treatment: Y = 391.7 + 4.57 X with r 2 = 0.9310 indicating a yield increase of 4.57 g m −2 (45.7 kg ha −1 ) over a distance of 2.5 m to 20 m from the trees.

  • Influence of orientation on wheat yield and photosynthetic Photon Flux Density (Qp) at the tree and crop interface in a Paulownia—wheat intercropping system
    Forest Ecology and Management, 1996
    Co-Authors: Charles P. Chirko, Michael A. Gold, Phu V. Nguyen, Jianjun Jiang
    Abstract:

    Abstract An on-farm field research study to characterize wheat yield in plots oriented 2.5 m east (E), west (W), and north (N) from the canopy of a north-south row of 11-year-old Paulownia trees was conducted at Zhengzhou, Henan Province, PR China. Wheat yield was higher on the east orientation compared with the west and north as determined by total grain weight and 1000-grain weight. Measured photosynthetic Photon Flux Density (Qp) was higher on E orientation during critical stages of wheat development. Soil pH, soil organic matter, available nitrogen, phosphorus, and air temperature parameters did not affect yield differences. In a second, related study, yield data from plots with and without plastic root barriers, placed to a depth of 1 m between the tree and winter wheat yield plots located 2.5 m E or W of the tree row, indicated that tree and crop root interaction had no effect on total grain weight or 1000-grain weight. However, there was a significant increase in yield of the E orientation as compared with the W.

Kachi Naoki - One of the best experts on this subject based on the ideXlab platform.

  • A measuring system for characterizing spatial and temporal variation of Photon Flux Density within plant canopies
    Forest Ecology and Management, 1997
    Co-Authors: Tang Yanhong, Kachi Naoki
    Abstract:

    Abstract A light measuring system is introduced to characterize spatial and temporal variation of photosynthetic Photon Flux Density on small scales within plant canopies. This system consists of an array of 100 gallium arsenide phosphide (GaAsP 1118), a high-speed data-logger with a maximum of 360 channels, and a portable computer. GaAsP cells, being small in size (total surface area of a single cell 5 × 6 mm), light in weight and inexpensive, make it possible to sample Photon Flux Density simultaneously for a large number of microsites. With the high-speed data logger, the system provides a useful tool for measuring dynamics of sunflecks within plant canopies. It is easy to separate spatial and temporal components of the variation in Photon Flux Density from the measurement using the system. A testing measurement was carried out in a tropical forest. Considerable spatial and temporal variations of Photon Flux Density along a 50 cm transect were observed in a gap of the forest. Some potential applications of the system were also discussed.

M P Fuller - One of the best experts on this subject based on the ideXlab platform.

  • effect of photosynthetic Photon Flux Density on growth photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of dieffenbachia cultivars
    Plant Growth Regulation, 2016
    Co-Authors: Mohammed Elsayed Elmahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S A Alshmgani, M P Fuller
    Abstract:

    The effects of 35, 70 and 100 µmol m−2 s−1 photosynthetic Photon Flux Density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m−2 s−1), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest irradiance. Stomatal resistance, transpiration rate and F v/F m values decreased with the incremental light irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m−2 s−1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all light treatments. These results depict that lower PPFD (35 µmol m−2 s−1) was suitable for acclimatization of Dieffenbachia plants. High PPFD (>70 µmol m−2 s−1) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels.

  • Effect of photosynthetic Photon Flux Density on growth, photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of Dieffenbachia cultivars
    Plant Growth Regulation, 2015
    Co-Authors: Mohammed Elsayed El-mahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S.a. Al-shmgani, M P Fuller
    Abstract:

    © 2015, Springer Science+Business Media Dordrecht. The effects of 35, 70 and 100 µmol m −2  s −1 photosynthetic Photon Flux Density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m −2  s −1 ), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest irradiance. Stomatal resistance, transpiration rate and F v /F m values decreased with the incremental light irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m −2  s −1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all light treatments. These results depict that lower PPFD (35 µmol m −2  s −1 ) was suitable for acclimatization of Dieffenbachia plants. High PPFD ( > 70 µmol m −2  s −1 ) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels