Foliar absorption coefficient

The foliar absorption coefficient k ranges from 0.3 to 1.3 for most plants. Light penetrates the vertically oriented blades of grasses rather easily in such cases, k can be near 0.4. What cumulative leaf area per ground area reduces the incident PPF by 95% for grasses with such a foliar absorption coefficient By Equation 9.5, the accumulated leaf area per unit ground area in this case is... 

Such a high foliar absorption coefficient applies to horizontal leaves with at least 0.5 g chlorophyll m-2, which can occur for crops such as potato, soybean, sunflower, and white clover (Fig. 9-6). 

Figure 9-6. Attenuation of PPF down through a plant community with erect leaves having a low foliar absorption coefficient of 0.4 and another plant community with horizontal leaves having a high k of 1.0.

Figure 9-7. Variation in leaf angle and hence foliar absorption coefficient with distance above the ground for (a) various idealized plants and (b) sugar beet measured at various canopy positions (Hodariova, 1979). Hie greater erectness of the uppermost leaves leads to a lower k for them and hence to better penetration of PPF down to the lower leaves.

Suppose that the foliar absorption coefficient is 0.7 for trees with an average... 

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