Is cool weather good or bad for grain fill?
Does this mean that we can expect another record-setting statewide average yield? Not necessarily so............................ Whoa! Why not?
We tend to forget about the excessive rainfall events that occurred throughout the state early in the season. Those rains prior to planting that provided such good opportunities to compact the soil with pre-plant field operations and with the planting operation itself. Those rains that resulted in large, drowned out areas in fields. Those rains that resulted in extended periods of soggy, saturated soils that took its toll on root development and health. Those rains that resulted in the loss of soil nitrate by leaching or denitrification. Consequently, many fields are not uniformly healthy. Stress from saturated soils during the ear size determination period may have compromised the top end ear size potential before pollination even occurred. Excessively cloudy weather during pollination may have reduced photosynthetic rates enough to interfere with the success of ovule fertilization and initial kernel development. In other words, in contrast to the record-setting year of 2004, the 2013 growing season has not been perfect.
I suspect that Indiana will end up with a solid overall average yield in spite of the early season stresses, in large part fueled by the favorable weather during pollination and grain fill. In essence, this is what USDA-NASS told us in their initial August yield estimate for Indiana. That being said, "it ain't over until it's over", meaning that the situation could still change.
By now, barely half of the state's crop has probably reached the dough stage of kernel development. At that stage, nearly half of the kernel dry weight is yet to be determined. Most fields have at least another 30 days of grain filling remaining before physiological maturity (kernel black layer) occurs. Some fields will require more than 30 days to reach physiological maturity. A lot could still happen, both favorable and unfavorable.
Many areas of the state have received less than normal rainfall for the past 30 days. The U.S. Drought Monitor does not currently (Aug 13) depict any areas of drought in Indiana, but compacted areas of fields, shallow-rooted crops, and crops in soils with naturally low water-holding capacity are in fact showing symptoms of drought stress. The current forecast for the remainder of the month is for above normal temperatures. Without meaningful amounts of rainfall, temperatures significantly above normal will cause similar stress in more fields around the state and interfere with the successful completion of the grain filling period.