農業気象
Online ISSN : 1881-0136
Print ISSN : 0021-8588
ISSN-L : 0021-8588
64 巻, 2 号
選択された号の論文の4件中1~4を表示しています
研究論文(英文)
  • 奥村 智憲, 谷 晃, 小南 裕志, 高梨 聡, 小杉 緑子, 深山 貴文, 東野 達
    2008 年 64 巻 2 号 p. 49-60
    発行日: 2008/03/10
    公開日: 2008/07/31
    ジャーナル フリー
    ブナ科コナラ属の植物はイソプレン放出能が高いことが知られており,アジアにも広く自生し固有種も多い。本研究では,東アジアにおける森林からの揮発性炭化水素放出量の推定とその放出特性の知見を得るために,日本における二次広葉樹林の主要な構成種であるコナラ(Quercus serrata)からのイソプレン放出の野外観測を行った。イソプレン放出速度と,同時に観測した光合成速度や気孔コンダクタンス,葉温,光強度との関係を調べた。さらに,炭素収支の観点からイソプレンとして放出された炭素量と純光合成で固定された炭素量の比(carbon ratio)を計算するとともにG93モデルの妥当性についても検討した。陽葉において純光合成速度は気孔開度の影響を受け,朝方に最大となり,それ以降は低下したが,イソプレン放出はその影響を受けず,おおよそ正午を最大とする日変動を示した。そのため,carbon ratioは午後に高まる傾向にあった。陽葉において葉温とイソプレン放出との関係を調べた結果,1000 µmol m-2 s-1以上のPPFDにおけるイソプレン放出速度は葉温と高い相関を示した。一方,陰葉のイソプレン放出は陽葉と同様に正午を最大とする日変動を示したが,その値は陽葉の約1/20であった。一日のcarbon ratioを求めた結果,陽葉で0.79~1.63%,陰葉で約0.3%であり,コナラの炭素収支を見積もる際に無視できない割合であった。次に,G93モデルのコナラへの適用を検討した結果,モデルの推定値と実測値は,陽葉で4 nmol m-2 s-1以下,陰葉で0.2 nmol m-2 s-1以下のRMS誤差でよく一致し,コナラのイソプレン放出速度の推定にG93アルゴリズムを用いることが可能であると示された。観測値を用いてG93モデルにより計算したコナラの基礎放出速度の平均値(陽葉:42.9 nmol m-2 s-1,陰葉:20.5 nmol m-2 s-1)から,コナラはブナ科コナラ属の中でもイソプレン放出能が高い部類に属することが示された。
研究論文
  • 石川 大太郎, 湯田 健之, 関岡 信一, 肥山 浩樹, 石黒 悦爾
    2008 年 64 巻 2 号 p. 61-68
    発行日: 2008/03/10
    公開日: 2008/07/31
    ジャーナル フリー
    This 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.
  • 山本 隆儀, 鈴木 雅南子, 奥谷 紘平, 田頭 怜子, 川上 洸, 伊藤 昌美
    2008 年 64 巻 2 号 p. 69-79
    発行日: 2008/03/10
    公開日: 2008/07/31
    ジャーナル フリー
    Remarkable 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.
短 報
  • 浜本 浩, 植野 耕造, 山崎 敬亮
    2008 年 64 巻 2 号 p. 81-86
    発行日: 2008/03/10
    公開日: 2008/07/31
    ジャーナル フリー
    A 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.
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