Corn planting tip – Watch maturities

It is a funny time of year to discuss corn maturity but as we make our final plans for spring it is important that we realize the factors that go into assessing corn maturity and the difference between physiological maturity and dry-down. Corn maturity starts after pollination and is complete at physiological maturity (black layer). Imagine the kernel as a glass and at pollination the glass is full of water. For the next 55 – 60 days we keep adding pebbles (starch and protein) to the glass (kernel) displacing water till the kernel is full. When the kernel is full of starch and protein and the maximum amount of water is displaced (there is still water between the pebbles (starch)). The kernel then full forms a layer of cells (bottom of the kernel) that turn black/brown forming what is called the black layer. The moisture of the kernel at this point is approximately 28 – 35 %.
What factors affect the rate of water displacement in the kernel?– Heat and sunlight
– Insects and disease – European corn borer, stalk rots, crown rots, rust
– Frost
– Cold weather – 4 to 5 days where maximum temperature does not exceed 130 C.
How do we get the rest of the water out of the kernel? Evaporation. The measure of moisture at harvest is a measure of dry down or the rate of evaporation of the remaining water from the kernel. Factors affecting the evaporation are: Thickness of pericarp (thin skin on the kernel), Kernel type (flint vs. dent), starch density (bu. weight) environmental (humidity), husk type/amount and ear orientation (by hanging down the ear sheds rain/dew accumulation)
How do we assess corn maturity?
Many factors are considered such as flowering (pollination) date to black layer formation and dry down. The most important is black layer compared to similar maturing products. Moisture is used to predict maturity but is more relevant when the harvest moisture is over 28 % moisture.
Taking it to the field A excellent corn year, such as 2010, often will skew corn maturities. It is important to not get caught planting too many late day varieties the following year. Maximum yield is produced with early planting dates for all the corn hybrid maturity groups (short, mid and full season). However, the yield reduction with delayed planting is the greatest with the full season hybrids compared to earlier maturing varieties.
At NK Brand we feel it is important to select a risk-free seed portfolio allowing you to manage the environmental risk of the growing season. By planting a 20:60:20 (short:mid:full season) maturity portfolio manages risk. When planting this type of portfolio, plant the full season varieties first, then the mid season and lastly the short season varieties. For maximum corn yield, all groups of hybrids should be planted as early as possible. Full season variety selection should include varieties that exhibit early flower and fast dry down traits. It is also important to have a late planted short season variety with the same characteristics.
Work with your seed specialist or NK Brand representative to build your corn portfolio.


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