STUDIES ON HEAT STORAGE OF PLANT CANOPY DUE TO THE VARIABILITY OF AIR AND SOIL TEMPERATURES.

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Heat storage and temperature of plant canopy is an important factor for plant growth, heat budget and remote sensing. The purpose of this research is to make clear some subjects with respect to the heat storage of plant canopy or temperature of plant. The first subject is the influence of soil heat flux under plant canopy. The second one is the comparison of plant temperature with a few models and the third one is the comparison of the observed leaf temperature with model.About the first subject, the following result was obtained. Under row plant canopy, there are large differences of the soil heat fluxes according to the positions. The soil heat flux observed in the interrow space may be two fold of the mean value under canopy. As the difference occurs systematically, it is not able to neglect in the analysis of heat budget.On the second, the estimation of the heat storage was tried by the following three models ; model using heat budget equation and gradient method, one layr model of plant canopy and a simplified multi-layr model. As the results, the one layr model was good in spite of the simple calculation method. The first model showed the large variation in every observed time. The last model has shortcomings of complicated calculation.On the third, observed leaf temperature was estimated by one layr model using the empirical parameters although it is difficult to identify the evaporation efficiency and the bulk transfer coefficient. Leaf temperatures obtained by multi-layr model were smaller than the observed one. It seems that the difference between the row plant canopy of the field and the uniform canopy in the theory chages the patterns of transmission of solar radiation in the canopy.