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This article in AJ

  1. Vol. 59 No. 1, p. 13-21
    Received: June 21, 1966

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Method for Calculating the Photosynthetic Response of a Crop to Light Intensity and Leaf Temperature by an Energy Flow Analysis of the Meteorological Parameters1

  1. S. B. Idso and
  2. D. G. Baker2



The productivity of plants is highly correlated with light intensity and leaf temperature. By an energy flow analysis of the meteorological parameters it is possible to calculate the daily variations of these two factors and predict the photosynthetic response of a crop. To do this a plant is considered as being composed of several different characteristic types of leaves. An energy balance equation is derived for each type and solved for the leaf temperature. Knowing leaf temperature and light intensity, photosynthetic rate curves are then constructed for the different types of leaves. An analysis of the crop geometry gives the fractions of the total number of leaves each characteristic leaf type comprises. The photosynthetic rate curves of the different leaf types are then multiplied by these fractions and added together to give an average photosynthetic rate curve for the plant (and thus the crop) as a whole.

Results are presented for a hypothetical crop at the beginning of growth, and at times of 50% and 100% ground cover. The effect of crop development through the growing season in modifying its energy environment and thus its rate of photosynthesis is made strikingly clear by this comparison.

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