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Volume 64, Issue 2
Displaying 1-4 of 4 articles from this issue
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Full Papers
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Motonori OKUMURA, Akira TANI, Yuji KOMINAMI, Satoru TAKANASHI, Yoshiko ...2008 Volume 64 Issue 2 Pages 49-60
Published: March 10, 2008
Released on J-STAGE: July 31, 2008
JOURNAL FREE ACCESSWe conducted field measurements of isoprene emissions from sunlit and shaded leaves of Quercus serrata, which is one of the major tree species in Japan. The measurements were conducted at the Yamashiro Flux Tower site in a deciduous broad-leaved forest. In June 2006, the isoprene emission rate (I), together with the net assimilation rate (A) and photosynthetic photon flux density (PPFD), was measured using a leaf cuvette. The experimental results demonstrated that I peaked at around noon for both the sunlit and shaded leaves, while A of the sunlit leaves peaked in the morning with a subsequent gradual decline. Consequently, the ratio of carbon emitted as isoprene to carbon fixed by photosynthesis (carbon ratio) increased during the afternoon. Data sets obtained at PPFD values higher than 1000 µmol m-2 s-1 revealed that highly correlated with the leaf temperature. The averages of the basal emission rate IS, calculated using the Guenther algorithm (G93), were 42.9 and 20.5 nmol m-2 s-1, respectively, for the sunlit and shaded leaves of Q. serrata. Our result indicates that Q. serrata should be categorized as a strong isoprene emitter. The measured I value estimated by the G93 model was consistent with the I value within a root-mean-square (RMS) error of 4 nmol m-2 s-1, suggesting that the G93 model can be used to determine the isoprene emission response of Q. serrata to PPFD and the leaf temperature.View full abstractDownload PDF (784K)
Full Papers (in Japanese)
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Daitaro ISHIKAWA, Takeshi YUDA, Shin-ichi SEKIOKA, Hiroki HIYAMA, Etsu ...2008 Volume 64 Issue 2 Pages 61-68
Published: March 10, 2008
Released on J-STAGE: July 31, 2008
JOURNAL FREE ACCESSThis study focused on how to identify a disaster stricken area hit by localized heavy rains using the remote sensing data from trees grown there. It has been known that the condition of a plant reflects the soil water-content. There is a good possibility, therefore, that trees in the areas caught in a heavy downpour should show some observable change in the remote sensing data.
The spectral responses of broad-leaf trees, Sudaji (Castanopsis cuspidate (Thunb) Schottky, var. sieboldii Nakai, sp. sudaji), were measured by a handheld spectroradiometer (400 nm to 1,000 nm at 3 nm intervals, IFOV with 3 degrees) at various water-stress levels. From this fundamental experiment, a couple of indices were found to be candidates; normalized differential vegetation index, NDVI and the ratio of reflectances in green and red regions, RIGR, which could represent the water-content. These results were confirmed using aerial photographs as well as video camera images. Images of a video camera with several band pass filters were analyzed of which two band pass filters, namely 660 nm and 750 nm, were usable. Indices were subsequently derived using the following equations, ND750, 660 = (R750 - R660)/(R750 + R660).
The concept of water-content fluctuation, WCF, representing the changes of water-content was introduced. WCF was derived by the following equation: WCF = [NDA - NDB]/NDB, where NDA and NDB represent the indices of the water-content of leaves. As the areas with lower WBF values collapsed after several weeks, it was confirmed this concept would be effective in estimating collapsed areas.View full abstractDownload PDF (1717K) -
Takanori YAMAMOTO, Kanako SUZUKI, Kohhei OKUYA, Reiko TAGASHIRA, Koh K ...2008 Volume 64 Issue 2 Pages 69-79
Published: March 10, 2008
Released on J-STAGE: July 31, 2008
JOURNAL FREE ACCESSRemarkable stained skins arose in persimmon ‘Hiratanenashi’ fruits after treatment for the removal of astringency via 95% ethanol at under room temperatures (RA95%ETOH) in 2004. When the surfaces were observed at high magnification before RA95%ETOH, barely detectable fine cracks were invisible to the naked eye. Further, however, a multitude of cracks stained with methylene blue were found. We presumed the cause to be salty wind damage because many typhoons had passed through the Japan Sea and our country during the late summer season and the dirty flecks after RA95%ETOH had been distributed on the unilateral fruit surfaces. Subsequently, in 2005 and 2006, certain tests were carried out to assess whether spraying salt solution might reproduce the fine cracks, and whether certain washing treatments could inhibit the damage. In addition, two different treatments designed to remove astringency were tested to prevent staining of the skin. The proportion of the cracked area relative to the fruit surface after the spraying of 5% salt solution without washing was well approximated to that found in 2004. The proportion of one in 2004 and that in several treatments with 5% or 3% salt solutions, meanwhile, were significantly higher than the lower salt levels or 0%, while the stained skin after RA95%ETOH was very similar to that found in 2004. Stained skins after the removal of astringency at a temperature of around 20°C by 35% ethanol or that by carbon dioxide gas was very little. We hypothesized an explanation that the fruits might not have been moistened with water drops during the latter two treatments because of the constant air temperature. As countermeasures to prevent damage and stained skins, the following were proposed: washing with copious water immediately after the passage of a typhoon, removal of remaining water droplets from plant surfaces by the vibration of branches and selection of the astringency removal method.View full abstractDownload PDF (1293K)
Short Papers (in Japanese)
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Hiroshi HAMAMOTO, Kouzo UENO, Keisuke YAMAZAKI2008 Volume 64 Issue 2 Pages 81-86
Published: March 10, 2008
Released on J-STAGE: July 31, 2008
JOURNAL FREE ACCESSA new film that absorbs ultraviolet radiation (UV) and fluoresces red light was tested as a rain shelter for the cultivation of turnip (Brassica rapa L.), spinach (Spinacia oleracea L.), and Welsh onion (Allium fistulosum L.). The effect of this UV-visible ray translation film on various growth parameters (height, fresh and dry weight, leaf area and leaf sheath diameter) was compared with those under normal clear film, new UV-cut film, and used UV-cut film respectively. The transmissivity of UV was about 70% for the normal clear film, about 20% for the UV-visible ray translation film and used UV-cut film, and about 10% for the new UV-cut film. The transmissivity of photosynthetically active radiation (PAR) was about 90% for the normal clear film and the new UV-cut film, and about 80% for the used UV-cut film, while the mean transmissivity of PAR was about 80% for the UV-visible ray translation film, with about 60% transmissivity of blue radiation and over 90% of red radiation. The UV-visible ray translation film did not promote the growth of turnip roots but did significantly promote the growth of spinaches and Welsh onions compared with the normal clear film. The UV-visible ray translation film cover promoted the growth of spinaches and Welsh onions to a similar or greater extent compared to the new UV-cut film and also to a greater extent compared to the used UV-cut film.View full abstractDownload PDF (691K)
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