農業気象
Online ISSN : 1881-0136
Print ISSN : 0021-8588
ISSN-L : 0021-8588
30 巻, 4 号
選択された号の論文の7件中1~7を表示しています
  • (4) 温床外表面からの顕熱伝達に及ぼす防風垣の効果
    高橋 英紀
    1975 年 30 巻 4 号 p. 155-160
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
    The effects of a shelter-hedge on sensible heat transfer from the surface of a hotbed were measured about a prototype of hotbeds in field and a model in a wind tunnel. The similarity problem between field measurement and model test was examined by using the data of heat transfer from the outer surface of hotbeds. And some model experiments were carried out to make clear the proper usage of shelter-hedge for the hotbed.
    The results obtained are summarized as follows:
    (1) Eq. (3) and Eq. (4) were used as a similarity law to compare the results obtained in model tests with those from field measurements. And the results of model test were in well accordance with those from field measurements (Fig. 4).
    (2) When the wind direction was perpendicular to a shelter-hedge, the effect of the shelter-hedge on reduction of heat transfer from a hotbed was distinguished. But in the case of the angle of the wind direction to a shelter-hedge was 45deg., the effect decreased extremely (Fig. 4).
    (3) The difference between the surface temperature of the hotbed and the air temperature slightly influenced the coefficient of sensible heat transfer under the calm condition. But the influence became negligible under the windy condition (Fig. 5).
    (4) The effects of closeness of the shelter-hedges on sensible heat transfer from the outer surface of the hotbed were examined by using the shelter-hedges with closeness of 30, 65 and 80%. The results indicated that the shelter-hedge with closeness of 30% was not useful to diminish the heat transfer. But the shelter-hedges with closeness of 65 and 80% were useful to diminish the heat transfer from the upper surfaces of hotbeds.
    (5) When the purpose of the shelter-hedge was to reduce heat transfer from hotbeds, the optimum distance between the shelter-hedge and the hotbed was about four times of the height of the shelter-hedge.
  • (4) キュウリ個葉の2, 3の光合成特性
    岩切 敏, 稲山 光男
    1975 年 30 巻 4 号 p. 161-166
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
    群落光合成を計算法によって求める場合の基礎資料となるキュウリ個葉の光合成特性のうち, 光ならびに温度―光合成関数について実験的に検討した。品種は王金半促成で, 無加温ハウス内に栽培した。測定には堀江 (未発表) の作成した3連の個葉光合成測定装置を使用した。
    結果はつぎのように要約される。
    (1) 光―光合成曲線は葉令 (展開後日数) あるいは葉位によって異なり, 下層の老葉では弱光のもとで光飽和に達し, 光飽和総光合成量Pmの値も小さい。Pmの最大値は群落の中層から上層にかけてみられ, 葉令dの関数としてつぎのように近似される。
    pm=23.8+1.248d-0.0361d2
    (2) 双曲線関数で近似した光―光合成関数式に含まれている係数bの値はあまり大きな変化を示さずb≅110mgCO2dm-2hr-1/(calcm-2min-1) とみなすことができる。この係数値とPmを求める式を用いると, 任意の時期における群落の層別の光―光合成関数式を決定することができる。
    (3) 光強度を0.6~0.7calcm-2min-1においたときの総光合成量の温度反応を相対値で示すと葉温Tlの関数としてつぎのように近似できる。
    RT=0.0500Tl-0.00076Tl2
    (4) キュウリ葉の形態形成に関係するパラメータ比葉面積は環境条件によって変化し, ポット栽培の値は普通に栽培されているものよりもやや小さい (葉が厚い)。ハウス栽培キュウリの比葉面積の平均値として300cm2g-1を採用してよいようわれる。
  • 高田 吉治, 玉木 研治
    1975 年 30 巻 4 号 p. 167-171
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
    The effective utilization of solar energy has been urgently required in the fields of agriculture and industry from the view point of energy saving. In order to fulfill this purpose, it would be essential to develop economical and highly reliable pyranometer to measure intensity of solar energy.
    Pyranometer of this type using N on P type silicon solar cell used for artificial satellites has been developed.
    As a result of three year running test with a thermopile type pyranometer, it was found that this new type has the output of smaller zero drift, quicker response and better stability. In addition to these, error caused by temperature dependence peculiar to semiconductors has been minimized by adopting temperature compensator.
    Japan Meteorological Agency has examined this type for one year and admitted the accuracy of within±2.5% error.
  • (7) 蒸散量と葉温との関係
    長谷場 徹也, 伊藤 代次郎
    1975 年 30 巻 4 号 p. 173-182
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
    The rate of transpiration from plant leaves and leaf temperature in the case of changing transpiration with a meteorological factor have been calculated from the equation of stationary energy-balance for a single leaf. The results obtained are represented in the forms of the relations between the transpiration rate and the difference of leaf and air temperatures, under some climatological conditions. Further, some observations are compared with the calculated results.
    i) Variation with solar radiation.
    When assuming that the stomatal aperture in terms of the coefficient of internal vapor transfer increases with solar radiation and the other meteorological factors are fixed, an increase in solar radiation under the conditions of lower air-temperature, higher humidity and smaller internal-transfer-coefficient increases both transpiration rate and leaf temperature. Under the opposite conditions, the increase in solar radiation increases the transpiration rate and decreases the leaf temperature, until the increase of the radiation increases both transpiration rate and leaf temperature when the radiation is above a certain amount.
    When the internal-transfer-coefficient remains constant as solar radiation varies, the transpiration rate and leaf temperature show a nearly proportional relationship, i.e. the transpiration rate increases and the leaf temperature rises with increasing solar radiation.
    ii) Variation with air temperature.
    In both cases when the internal-transfer-coefficient increases with air temperature and when it remains constant as air temperature varies, an elevation of air temperature produces an increase in transpiration rate and a decrease in temperature difference between leaf and air; the leaf temperature rises with air temperature.
    iii) Variation with relative humidity.
    In all cases when the internal-transfer-coefficient decreases or increases with decreasing humidity and when the coefficient remains constant, the transpiration rate increases as humidity varies and the leaf temperature is decreased. The relationships between them are almost linear.
    iv) Variation with wind speed.
    Simulation was done on the assumption that the internal-transfer-coefficient remains constant as wind speed varies.
    When the transpiration is suppressed under the conditions of lower air temperature, higher humidity and smaller internal-transfer-coefficient and the leaf-air temperature difference becomes larger under the conditions of higher solar radiation, an increase in wind speed diminishes both transpiration rate and leaf temperature.
    Under the opposite conditions, the increase in wind speed increases both transpiration rate and leaf temperature.
    Under the medial conditions of air temperature, relative humidity, internal-transfer-coefficient and solar radiation, the tendency for the transpiration rate to increase with wind speed is general and then the leaf temperature falls.
    v) Observations.
    The relations between transpiration rate and leaf temperature obtained from some experiments using citrus, sweet potato and paddy rice plant in controlled environments were in good agreement with the simulation of the leaf-heat-balance.
  • 岩波 悠紀, 内藤 俊彦, 飯泉 茂
    1975 年 30 巻 4 号 p. 183-185
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
  • 鈴木 義則, 谷口 利策
    1975 年 30 巻 4 号 p. 187-190
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
  • 奥山 富子
    1975 年 30 巻 4 号 p. 191-194
    発行日: 1975/03/15
    公開日: 2010/02/25
    ジャーナル フリー
    水稲群落の蒸散・光合成・物質生産に密接な関連をもつ群落表面温度 (表層葉群の平均温度) の実態, ならびに外部要因との関連を明らかにすることを目的にし, 赤外線放射温度計を用いた実験的研究を行なった。得られた結果はつぎのように要約される。
    (1) 群落表面温度は気温より2~3℃低いが, 十分な広さをもつ水田地帯においてはこの差はさらに小さくなるものと考えられる。
    (2) 表面温度は葉温測定値に非常に近く, その差は1℃以下の測定誤差の範囲内にある (Fig. 2)。
    (3) 表面温度Tsは気温Taとの相関が高く, 本実験条件下での両者の関係はつぎのようにあらわされる。
    Ts=1.01Ta-2.74
    (4) 群落条件下の温度差 (Ta-Ts) に及ぼす日射・風速の影響は, 個葉の場合のように明確にあらわすことはできない (Fig.5)。
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