農業気象
Online ISSN : 1881-0136
Print ISSN : 0021-8588
ISSN-L : 0021-8588
59 巻, 4 号
December
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)
  • 大場 真, 高木 健太郎, 高橋 英紀
    原稿種別: その他
    専門分野: その他
    2003 年 59 巻 4 号 p. 259-267
    発行日: 2003年
    公開日: 2004/12/17
    ジャーナル フリー
    断続光(光強度が高·低値に周期的に変化する)条件における植物の光合成についての研究が行われてきた。過去の研究に基づき, 次の仮説を立てた:平均光合成速度(A-)は, 断続光周期約102秒オーダーで最小値を示す;周期が1あるいは103秒オーダーでは, A-は平均光強度における定常光合成速度(A)あるいは各光強度におけるAの平均にそれぞれ近づく。この仮説を確かめるための葉モデルを開発し, 断続光条件における周期とA-の関係を推定した。この仮説はこのモデルによって確認された。本研究で示した変動光の時間スケールと平均光合成速度の関係は, 複雑な光環境における植物の動態を推定するための情報を提供している。
研究論文
  • 石神 靖弘, 清水 庸, 大政 謙次
    原稿種別: その他
    専門分野: その他
    2003 年 59 巻 4 号 p. 269-276
    発行日: 2003年
    公開日: 2004/12/17
    ジャーナル フリー
    In a previous paper, we modified some sub-models of BIOME3 to be applied to 1×1 km mesh data in order to increase the accuracy of simulation.
    Using this modified model, we estimated potential natural vegetation distribution under climatic change using 4 types of GCM experiment data. GCM data that can be used presently have rough spatial resolution, so it is difficult to estimate the effect of climatic change at a local scale. Therefore, we used GCM data around Japan that was interpolated to a 10×10 km mesh.
    We calculated the NPP, and predicted the distribution of potential natural vegetation and its vulnerability for the 2020s, 2050s and 2080s. Results from the simulation indicated the possibility of 60-100% increase of NPP in the 2080s. The increase in NPP was explained by the increase in air temperature and the concentration of CO2. Potential natural vegetation in Japan would be affected over a wide area by climatic change. In particular, the alpine plants/subalpine conifer forest area would decrease. In mixed forest in the Hokkaido area, where broad-leaved deciduous trees and conifer trees coexist, broad-leaved deciduous trees would become dominant. Broad-leaved evergreen forest area would expand, and the subtropical forest would to a prior species along the coastline of western Japan.
  • 脇山 恭行, 井上 君夫, 中園 江
    原稿種別: その他
    専門分野: その他
    2003 年 59 巻 4 号 p. 277-286
    発行日: 2003年
    公開日: 2004/12/17
    ジャーナル フリー
    The present study was conducted to show a simple model for rice yield predicting by using a vegetation index (NDVI) derived from satellite and meteorological data. In a field experiment, the relationship between the vegetation index and radiation absorbed by the rice canopy was investigated from transplanting to maturity. Their correlation held. This result revealed that the vegetation index could be used as a measure of absorptance of solar radiation by rice canopy. NDVI multiplied by solar radiation (SR) every day was accumulated (Σ(SR·NDVI)) from the field experiment. Σ(SR·NDVI) was plotted against above ground dry matter. It was obvious that they had a strong relationship. Rice yield largely depends on solar radiation and air temperature during the ripening period. Air temperature affects dry matter production. Relationships between Y SR-1 (Y: rice yield, SR: solar radiation) and mean air temperature were investigated from meteorological data and statistical data on rice yield. There was an optimum air temperature, 21.3℃, for ripening. When it was near 21.3℃ in the ripening period, the rice yield was higher. We proposed a simple model for yield prediction of rice based on these results. The model is composed with SR·NDVI and the optimum air temperature. Vegetation index was derived from 3 years, LANDSAT TM data in Toyama, Ishikawa, Fukui and Nagano prefectures at heading. The meteorological data was used from AMeDAS data. The model was described as follows:
    Y=0.728 SR·NDVI−2.04(T−21.3)2+282 (r2=0.65, n=43)
    where Y is rice yield (kg 10a-1), SR is solar radiation (MJ m-2) during the ripening period (from 10 days before heading to 30 days after heading), T is mean air temperature (℃) during the ripening period. RMSE was 33.7kg 10a-1. The model revealed good precision.
  • 濱嵜 孝弘, 岡田 益己
    原稿種別: その他
    専門分野: その他
    2003 年 59 巻 4 号 p. 287-296
    発行日: 2003年
    公開日: 2004/12/17
    ジャーナル フリー
    The effect of row cover on the growth of Komatsuna (Brassica campestris L. rapifera group) was evaluated using a simple model describing the relationship between temperature and leaf growth. The model was developed from a growth chamber experiment and shows that a) relative leaf area growth rate (RLGR) varies inversely as the 0.6th power of leaf area (LA) and b) RLGR is related to temperature by a sigmoid curve. Separate field experiments were carried out over six periods of growth and the parameters of the model were derived so as to fit the model to the results of these experiments. The growth-promoting effect of row cover was best described when the model was driven by soil temperature rather than air temperature, and it was therefore concluded that the growth-promoting effect of row cover strongly depends on its ability to warm the soil. The model-aided analysis of field-grown Komatsuna showed that leaf growth under row cover was stimulated most at lower temperatures and in the earlier growth stages. The effect of temperature was explained by the relationship between soil temperature and RLGR, in which the temperature-stimulation of RLGR decreases at higher temperatures. The effect of early growth stage was due to the enhanced rate of soil warming that results from better penetration of solar radiation to the soil surface when canopy leaf area is relatively undeveloped. Although both of these effects are already known empirically, the model-aided analysis used in the present study is able to explain them quantitatively.
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