There were some very interesting correlations between PhotosynQ data and crop and stover yield (see combined results link below). When combining all measured leafs on each plant, SPAD was positively correlated with grain yield while PhiNPQ (active regulation of energy away from photosynthesis) reduced yields. The results from individual leaves (top, middle, or bottom) were all different (see links below)
Combining all the PhotosynQ data with harvest and treatment information, predictive models with r2 of over 0.5 were found. This is excellent considering that there doesn't appear to be very large differences between the yields of the various treatments.
These results were analyzed by Dan TerAvest using the statistical program R.