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Throughout the growing season, farmers, market analysts and government officials all rely on estimates of corn growth phases as they make management and marketing decisions for the crop.
The Kansas State University Department of Agronomy identifies the two main growth stages of corn as vegetative and reproductive. The separation of these two stages is the appearance of silks and leads into the pollination period (R1).
Following pollination, corn crops are monitored throughout the reproductive stages for kernel development, which gives farmers and analysts indicators of maturity and yield.
The blister stage (R2) has small white kernels with fluid that is usually clear and 85 percent water.
The milk stage (R3) follows when kernels begin to show a yellow color. The inner kernel fluid has a milky texture from accumulating starch. Stress at this stage can limit kernel size and weight.
The dough stage (R4) follows as the ear becomes brighter yellow, accumulated starch begins to thicken, and the cob develops a reddish color.
The dent stage (R5) begins when kernel moisture content begins to decrease from approximately 55 percent, getting its name from how the kernels look as starch begins to harden at the top of the kernel and moves down toward the cob. Stress or a frost at this stage only affects kernel weight.
The final stage is physiological maturity (R6) and occurs when the hard starch layer of the kernel reaches the cob and a black layer has formed. At the beginning of this stage, the kernel is 30 to 35 percent moisture depending on variety and environment.
Farmers monitor the progression of drying to a level that fits their harvest and storage plans, usually 15 to 20 percent moisture.
For additional information on corn growth and development visit: http://www.agronomy.k-state.edu/extension/crop-production/corn/corn-grow...