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Guidelines For Understanding Corn Production

• A general Rule of Thumb is to plant corn after the morning temperature at the 2" depth is above 50 degrees.
• Working fields wet causes compaction which effects crop growth for the entire season.
• When planting early into No-Till, increase the population 5 to 10%.
• When determining plant populations, select a realistic goal for your farm. Underplanting may limit yields; overplanting can cause barren stalks, small ears, increased disease pressure and standability problems.
• Full season hybrids usually respond more to early planting than shorter season hybrids.

Planting to Emergence

• A dormant kernel will absorb approximately 30% of its weight in moisture to initiate the chemical changes needed for the germination process to begin.
• Corn needs approximately 110 growing degree units to emerge (usually 7 to 10 days).
• For the first 2-3 weeks, the kernel provides the food for the growing plant, as the food reserves are depleted, the roots assume this responsibility.
• As the corn plant emerges, the growing point is located 1-11/2" below the soil surface, and at this time begins to initiate all foliage leaves, ear shoots and the tassel.

Emergence to Knee High

• Under ideal growing conditions, the newly emerged corn plant will unfurl leaves from the whorl at the rate of approximately 1 leaf every 3 days.
• By the time 4 leaves have emerged, approximately 5" tall, the corn plant has begun to create the root system and leaf structure that will be used to later support ear and grain formation. The tassel is initiated in the tip of the stem, but is still below the soil surface. All leaves and ear shoots that the plant will eventually produce have now been initiated.
• When 6 leaves are fully emerged, the nodal roots become the permanent functioning root system of the corn plant.
• When 8 leaves are fully emerged, the corn plant begins to enter a stage of extremely rapid vegetative and vertical growth. The corn plant is now determining how many rows of kernels the new ear will have. This determination cannot be increased later in the growing season. The growing point is now 2-3 inches above the soil surface.

Knee High to Pollination

• The corn plant has now entered a stage of extremely rapid, steady growth, placing heavy requirements on the root system to supply water and nutrients. New leaves unfurl at a faster rate of 1 every 2 days. The tassel now begins to develop rapidly. Although the number of rows of kernels per ear has already been established, the determination of the number of kernels per row will not be complete until 1 week before silking.
• As the plant nears pollination, the leaves unfurl at a faster rate of 1 every 1 or 2 days.
• By the time the tassel has emerged, the corn plant has reached its full height, and the root system has reached its maximum size. Pollen shed normally begins 2-4 days after tassel emergence and continues for 5-8 days. Silks usually appear 1 or 2 days after pollen shed begins, growing from 1-1 1/2 inches per day until fertilized. Pollination is not a continuous process, with pollen shed occurring for only a few hours each day, and only when the tassel is dry. Under normal field conditions, 95% of the pollen falling on a given ear will have originated from another corn plant.
• Moisture, heat, and other environmental stresses occurring 2 weeks prior to 2 weeks after silking can result in very large yield reductions. Moisture stress can delay silk emergence, while heat stress can reduce pollen viability.
• By tasseling, the corn plant has (during the first 50 days of growth):
  • absorbed 50% of its Nitrogen needs
  • absorbed 33% of its P20S requirement
  • absorbed over 50% of its K20 needs

Pollination Maturity

• Within 2 weeks after silking, the kernels resemble a blister in shape. The kernels are now approximately 85% moisture.
• By the end of the 3rd week after pollination, the kernels display a yellow color on the outside and the inner fluid is milky-white due to starch accumulation. The kernel is now approximately 80% moisture.
• Starch accumulation continues into the 4th week as the milky inner fluid now thickens to a pasty consistency. The kernel has now reached about 70% moisture.
• After the 5th week, half the kernels are usually dented and the kernel has reached about 60% moisture.
• By the 6th week, the kernels contain about 55% moisture, are 3-3 1/2 weeks from maturity and have accumulated 3/4 of their mature dry weight. By the time 95% of the kernels on the ear have dented, the moisture is about 50%.
• Black layer occurs when the kernel has reached its maximum dry weight. Average kernel moisture is now 28-35%. Black layer is caused by the collapse and compression of several layers of cells near the tip of the kernel and is an indication the kernel is no longer receiving photosynthate from the plant and signals the end of kernel growth for this season.
• Stress encountered at this stage of development will reduce yields by reducing kernel weights.

We hope this information will help you to better understand the process that a corn plant goes through during the season.

Proper inspection and maintenance of planting and harvesting equipment will greatly increase stand and yield.

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