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Today I visited another corn field in Champaign, Illinois to collect gas samples. The corn growing stage is mostly in R1 stage, but I saw some corns reached to R2 stage.

After R1 (silking) stage, the period to determine kernel number has gone, and new period is here. It’s kernel weight. Approximately 12 days after silking, silks become dark, and will dry out rapidly over time. In this stage, the developing kernels are white “blisters” (resemble a blister) on the cob and contain abundant clear fluid. Therefore, we call this stage R2 (Blister) stage. Usually, R2 stage occurs about 10 – 12 days after silking.

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