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Volume 57, Issue 3
Displaying 1-6 of 6 articles from this issue
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Takumi KISHIDA, Toru IWATA, Takeshi MIURA, Eiji OHTAKI, Katsutoshi NIS ...2001 Volume 57 Issue 3 Pages 117-126
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe carbon dioxide concentration (pCO2) in irrigation water in a rice field was measured from August 9 to 11, 1996. The pCO2 showed low values of a few μatm in the daytime, and high values over 2, 500μatm (=253.3Pa) in the early morning. This large diel change of pCO2 is associated with three factors; water temperature change, gas exchange across air-water interface, and biological consumption of carbon dioxide in water through photosynthesis. The effect of water temperature change results in the modification by 60μatm in pCO2 (2% of the diurnal change) taking into account the diurnal change of water temperature (ca. 6°C). The carbon dioxide exchange across the air-water interface varied from -2.7 to 28.4μgm-2s-1, with a daily mean of 5.5μgm-2s-1, causing a variation of about 609μatm per day (24% of the diurnal change). Dissolved carbon dioxide [CO2] and oxygen [O2] data showed the photosynthetic (respiration) relationship: [CO2]/[O2]=-106/138. This suggests the possibility that the photosynthetic (respiration) activity of algae is responsible for the residual fraction (ca. 73%) of the diurnal change of pCO2. It is also noted that there was a measurable increase in the downward carbon dioxide flux (ca. 0.3mgm-2s-1) from the atmosphere when the paddy field was flooded compared to when it was drained. The increment of the downward carbon dioxide flux was compatible with the carbon dioxide emission rates at the soil surface. The carbon dioxide exchange rates at the water surface were smaller by a factor of 1, 000 compared with fluxes over a rice stand and smaller by a factor of 100 than the carbon dioxide emission rates at the soil surface.View full abstractDownload PDF (1193K) -
Ko NAKAYA, Kazuhiro SHOJI2001 Volume 57 Issue 3 Pages 127-133
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSChlorophyll fluorescence is known to be a sensitive probe of photosynthesis. Laser induced fluorescence (LIF) is useful for remotely sensing physiological information of plants by optical measurement. However, it is difficult to assess the LIF independently because of changes in background light. Background light, like sunlight, not only stimulates photosynthetic reaction but also induces fluorescence.
To demonstrate the possibility of detecting changes in photosynthetic reaction according to background light from the LIF spectra, the correlation between LIF spectra and intensity of incident light on leaves was investigated.
The LIF spectra from rice (Oryza sativa L.) leaves, which were illuminated with a metal halide lamp as background light, were measured. A gated CCD camera with monochrometer was synchronized to a pulsed UV-laser (Nd: YAG, 355nm) to detect the LIF spectrum under background light of different intensities. The LIF magnitude increased linearly with the laser intensity at each intensity of background light. The slope of fluorescence against laser intensity was considered to be a measure of fluorescent efficiency. The fluorescent efficiency increased with intensity of illumination. This increase of fluorescent efficiency was mainly caused by the increase of blue-green fluorescence (BGF) but chlorophyll fluorescence was constant. These changes of LIF spectra can be explained by the interaction of the fluorescent efficiency of chlorophyll and re-absorption of BGF; these phenomena reflect the redox state of the first electron acceptor (QA) in the photosynthetic reaction. The ratio of regression coefficients of BGF to chlorophyll fluorescence against the laser intensity changed in accordance with the change of photosynthetic rate of rice leaves.
Photosynthetic information of leaves was detectable by analyzing the correlation between induction intensity and LIF spectra under changing background light.View full abstractDownload PDF (947K) -
Rie SEO, Haruo SUZUKI, Duangpaeng ARCHANA, Toshiyuki MATSUI, Yukihiro ...2001 Volume 57 Issue 3 Pages 135-144
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe purpose of this paper is to clarify the effect of the amount of contact between film mulch and row surface upon the variations of 10 soil temperatures and their deviations at the same 10cm depth, and thereby properly compare the soil temperatures of two plots.
Three process zones, consisting of a zone without mulch, a zone with black polyethylene mulch, and a zone with transparent polyethylene mulch, were established. Each zone was divided into three sub-zones whose contact percentages, that is, the amount of contact between the variations of mulch and the soil, were set to 100%, 70%, and 50%, respectively. Each sub-zone was further divided into two plots: one where no vegetation would be grown, and the other where radish plants would be grown. In all, 18 experimental plots were prepared.
The daily range in soil temperature was measured beneath each of the 18 plots. The order relation of the daily ranges among the plots was transparent mulch (1.8°C to 2.7°C)>no mulch (1.2°C to 1.9°C)>black mulch (0.8°C to 1.1°C).
The soil temperature order of the two plots based on t-test was as follows : The soil temperature at no mulch zone at 6:00 was 100% plot >70% plot >50% plot. The temperature at 15:00 was 50% plot >70% plot >100% plot. Accordingly, temperature change in the 50% plot was most significant. Soil temperature in the black mulch zone at 6:00 was highest in the 50% plot. Therefore, the insulating effect at the black mulch zone was the greatest. At 15:00, temperature rise in the 70% plot was most significant. In the transparent mulch zone, the 100% and 70% plots showed an equivalent insulating effect at 6:00, and the temperature rise in the 50% plot at 15:00 was largest.
The soil temperature difference between two plots for each mulch zone, the distribution range of the difference between the 100% plot and the 70% plot, and that between the 100% plot and the 50% plot, all increased with increasing amounts of solar radiation. In particular beneath the black mulch with vegetation, the kurtosis of the soil temperature distribution decreased with increasing amounts of solar radiation. Beneath the transparent mulch without vegetation, the tendency toward decreases in the largest frequency became evident with the same variation.View full abstractDownload PDF (1342K) -
Tomomi TAKEDA, Takashi HIRANO, Shin-ichi URANO, Ikuo HORIGUCHI2001 Volume 57 Issue 3 Pages 145-153
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSCanopy structure of crops is an important factor determining the radiation environment of the canopy. Although many researchers have dealt with foliage distribution by using a probability density function, studies that reproduce a spatial destribution and spatial form of foliage in 3 dimensional (3D) space have only recently been reported. In this study, we developed a geometric model by using L-system to reproduce the form of sunflower plants in 3D space. The model consisits of frame and leaf models. In order to obtain functions to illustrate the frame model, positions of nodes, leaf bases, and leaf tips were measured from photographs of sunflower plants taken at five different stages in a growing season, and lengths of internode, petiole and leaf were determined. Moreover, lengths of five lateral veins, and divergence angle between midrib and fifth lateral vein were measured.
Growth curve of internode and petiole could be expressed as a logistic function of step number in L-system. Leaves elongated as a function of petiole length. Zenith angle of petiole decreased with step number from 1 to 7, and then stabilized at about 35°. Leaf zenith angle was related to petiole zenith angle. Divergence angles between successive leaves differed in different phyllotaxis. In distichous phyllotaxis, divergence angle was 180° between the leaves at the same node, and 90° between the leaves at successive nodes. On the other hand, in alternate phyllotaxis, divergence angle was about 135°. Leaf expansion could be related to increase in leaf length.
In conclusion, the geometric model using L-system successfully reproduced the growth of sunflower plants with increase in node number.View full abstractDownload PDF (1041K) -
Tomoko NAKANO, Chie KAMEI2001 Volume 57 Issue 3 Pages 155-159
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDiurnal variation in CO2 flux from the soil was measured by a closed chamber technique at a developed land site in Tokyo from September to November in 1999. The measurements were made four times for 24-h periods at two fixed sites where there was no plant cover (A) and where Miscanthus sinensis was dominant (B). CO2 fluxes averaged 98.2mg CO2 m-2h-1 at the site A and 184.3mg CO2 m-2h-1 at the site B. The fluxes from both sites showed a clear diurnal variation, which was high during the day and low at night. The temporal variation was highly correlated with the air and soil temperatures, especially at depths of 1 and 5cm. The relationship between CO2 flux and temperature was exponential. The CO2 flux increased exponentially 1.99 times when the soil temperature at 1cm deep increased by 10°C.View full abstractDownload PDF (654K) -
Floriculture and Vegetable Productions under Cover and in the OpenIn-Bok LEE, Sadanori SASE, Limi OKUSHIMA, Guo Yu QIU2001 Volume 57 Issue 3 Pages 161-168
Published: September 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESS
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