Enhancement models at high light intensities.

The separate package and spillover models of photosynthetic enhancement are generalized and extended to light saturation assuming hyperbolic or exponential rate versus intensity curves. The available data are more consistent with the exponential model at high light intensities. Two significant conclusions follow: (a) the decreases in enhancement observed at high light intensities are accounted for by the curvatures of the light intensity curves for photosynthesis, and (b) nonlinearity of rate versus intensity curves may be sufficient to reduce enhancement greatly even when the intensity curves appear linear.