Grain Fill Stages in Corn


Today managing your corn crop requires knowledge of the different growth stages of the corn plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Throughout the growing season I will discuss the various corn growth stages and management issue at each stage. 

Grain Fill Stages

The grain fill period begins with successful pollination and initiation of kernel development, and ends approximately 60 days later when the kernels are physiologically mature.  During grain fill the plant will do all it can to “pump” dry matter into the kernels, sometimes at the expense of the health and maintenance of other plant parts including the roots and lower stalk.

Kernel Development. The embryo and non-embryo sides of each kernel.

Cross-section of primary ears from R1 to R6. The embryo and non-embryo sides of each ear are shown once they are distinguishable.


A stress-free grain fill period can maximize the yield potential of a crop, while severe stress during grain fill can cause kernel abortion or lightweight grain and encourage the development of stalk rot (see table 1). The health of the upper leaf canopy is particularly important for achieving maximum grain filling capacity. Some research indicates that the upper leaf canopy, from the ear leaf to the uppermost leaf, is responsible for no less than 60% of the photosynthate necessary for filling the grain.


Table 2 shows the average amount of water needed for each growth stage and the cumulative total for the entire growing season.


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