, Farm Journal intern
The grain filling period is the final important stage in growth and development of the corn crop. Stress on the crop during this time period can mean lower yields, says Robert Nielsen, professor of agronomy at Purdue University.
Nielsen says the most common stresses that occur from July to early September, the grain filling period, are drought stress, severe hail storms and severe leaf diseases.
Though the farmer can't do much for the corn that is suffering from one or more of these stresses, the best way to combat the stresses late in the season is to begin early. For best results, growers should try to raise a vigorous and healthy crop that can withstand some of these weather conditions and diseases, he says.
Yield loss in the corn crop can result from unfavorable weather and diseases during the grain filling period.
The loss can occur from:
- Stand loss
- Incomplete kernel set
- Decreased kernel weight
- Premature plant death
Stand loss during the grain fill period usually causes greater yield loss than the stand loss in the vegetative phase, Nielsen says. When stand loss occurs in this late period, the ears have stopped growing, which means their size is set. The only thing that can compensate for the lesser competition of a thinner stand is the kernel weight.
The level of development of the kernels is the kernel set. If the kernel set is incomplete, it may not be obvious. The size of the cob and husk will continue to grow, even if the kernels aren't developing properly, Nielsen says. Unsuccessful fertilization of the ovules during pollination is one of the causes of an incomplete kernel set. If there is unsuccessful fertilization, there are ovules that never developed into kernels, he says.
Abortion of fertilized ovules is another cause of an incomplete kernel set. This means that the kernels began developing but never finished. These kernels will be shrunken, mostly white, and they may have the yellow embryo visible inside, he says.
Stress during dough and dent stages of the grain filling period may result in kernel black layers forming prematurely, which decreases kernel size and weight, Nielsen says. Premature plant death can stop photosynthesis of the whole plant or the leaves of the plant, which stops the development of the crop.
For More: Effects of Stress During Grain Filling in Corn
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