What is the impact of leaf morphology in maize?

Research Questions

1. How does the canopy level leaf structure (i.e. the 3D position of all canopy elements) in maize affect the received distribution of light at the crop scale?
   
   Since photosynthetic response is non-linear, one of my postulates is that instead of evaluating the total received light by a canopy, it is more important to examine the distribution of received light (i.e. how much area and time receive each different level of irradiance). I also hope to understand how differences in morphology (such as more upright vs. more curved leaves) impact both self and neighbor shading.
   
   The approach here is to (i) measure the 'complete' 3D position of all leaves within small plots of two different maize hybrids (Pioneer 3394 vs. 3306), and (ii) use this data as an input to a light interception model to predict the amount of received light by each leaf section during the critical times of the growing season.
   
   
2. With what accuracry can the distribution of received light (including direct, diffuse, ...) be modeled?
   
   Answering the above question requires having a functional (accurate?) model of light interception for maize. Methods (such as the Z-buffer algorithm) seem well established for estimating received direct light, although there are outstanding questions as to the required accuracy of the 3D canopy measurements. Efficient methods for estimating diffuse light are lacking. The approach here is to measure above canopy direct and diffuse light, 3D canopy structure, and within-canopy light (at some number of points) and evaluate what type of accuracy can be achieved toward predicting incident light. The model will predict what light should be present at each point within the canopy for a given solar position, and I will assess the model by comparing these estimates to the measured values.
   
   Based on the initial results, I will evaluate whether it makes sense to try to understand how much additional accuracy can be obtained (and at what processing cost) by also estimating transmitted and reflected light within the canopy.
   
   
3. What is the impact of violations of the assumptions of the LAI approach on the precision of light interception models?
   
   Most agricultural (and other) models use LAI (leaf area index) and a Beer's law approximation to estimate the amount of intercepted light. However, I think there are two problems with this. First, this approach assumes that all leaf material is uniformly distributed throughout each layer, which of course isn't true. Second, determination of k (the extinction coefficient) is based on measuring mean light levels for different heights within the canopy. As such, this approach will only (at best!) estimate mean light levels. As described above, because of the non-linear nature of photosynthetic response to incident light, using mean values will lead to incorrect estimates of photosynthetic response.
   
   The important question however is whether these violations matter when it comes to estimating received light.

Background