Purdue newletter had a good article on heat during grain fill.


http://extension.entm.purdue.edu/pestcrop/2010/issue19/index.html#excessive

Here is the take home nugget:

High kernel set does not guarantee high yields. Warm and wet conditions (general absence of drought) through late vegetative growth in Indiana meant that we had high potential kernel numbers this season. We have had some kernel abortion occur in the first 2 weeks after pollination, and time will tell what the final kernel weights are going to be for the kernels that were retained. Final kernel size has considerable flex (20% plus variation in weight per kernel within hybrids at a particular plant density) so final yields are going to be affected by how much the current and future weather affects the supply of assimilates from the plant to the grain.

Bottom line is... we will not KNOW until the combines roll. My gut feeling is that we will have lighter corn than the last couple years.