作物群落の生産機能および状態の非破壊非接触診断に関する研究 : 第2報赤外線放射センサによるトウモロコシキャノピー温度の特性および気象要因との関係

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The present study was aimed to obtain basic knowledge to monitor remotely the physiological-ecological functions and status of crop community. In this paper the features of canopy temperature in corn crop field and its relations with climatic factors measured simultaneously by a multi-sensing system were investigated. The results obtained are summarized as follows: 1. The coefficients of variance of canopy temperature were as small as around 1% for uniform communities (Table 1). 2. The mean temperature of leaves measured by thermocouples differed between adaxial and abaxial surfaces by 0〜0.3℃ under cloudy conditions and 0.1〜1.2℃ under sunny conditions. The temperature of adaxial surface was always higher than abaxial one. The coefficients on variance of leaf temperature within upper layer of crop community were 1.3〜2.5% under cloudy conditions and 2.5〜6.5% under sunny conditions. 3. The canopy temperature measured by an infrared thermometer was relatively lower than the mean temperature of upper layer of the crop community measured by thermocouples. Because of high correlation between them, the latter could be successfully estimated by the former (Fig. 2, Eq. 1). 4. The canopy temperature varied in the same pattern as that of ambient air temperature keeping lower by 2〜5℃ under steady conditions of the other factors. A very high correlation was observed (r = 0.989) between the simultaneous values of them. The time constant of the response of canopy temperature was estimated to be very short and the temperature seemed to respond almost instaneously (Fig. 3). 5. A linear relationship (r = 0.8) was obtained between the air-canopy temperature difference and the vapor pressure deficit of air, and the canopy temperature decreased in proportion to the increment of the vapor pressure deficit (Fig. 4). The depression of the canopy temperature is caused by the cooling effect of the transpiration. It is considered that this relationship was brought about under such conditions that crop water deficit was so small as to give no significant influence on stomatal resistance and the potential transpiration. The above result suggests that the air-canopy temperature difference may be a good index of crop water stress in arid zones where the deficits of air vapor pressure and soil water, both, are large. 6. According to a multiple regression analysis, variance of canopy temperature was estimated almost fully by the three climatic factors ; air temperature, vapor pressure deficit and PAR (r = 0.91〜0.96). Canopy temperature had close relation with these three variables as indicated by the partial correlation coefficients : 0.87 for air temperature, -0.74 for VPD and 0.82 for PAR. And the mean ratio of the contribution of them were estimated as 0.86 for air temperature, -0.62 for VPD and 0.60 for PAR. These relationships were obtained within a wide range of those three factors (Table 2, Fig. 5).
日本作物学会の論文
1987-03-05

作物群落の生産機能および状態の非破壊非接触診断に関する研究 : 第2報赤外線放射センサによるトウモロコシキャノピー温度の特性および気象要因との関係

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作物群落の生産機能および状態の非破壊非接触診断に関する研究 : 第2報 赤外線放射センサによるトウモロコシキャノピー温度の特性および気象要因との関係

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作物群落の生産機能および状態の非破壊非接触診断に関する研究 : 第2報赤外線放射センサによるトウモロコシキャノピー温度の特性および気象要因との関係