Corn School: Kernel weight pumps up yield

2021 was a big year for corn yield in Ontario. Although not official, the average yield is expected to check in at just over 200 bu/ac — a new record.

On this episode of RealAgriculture’s Corn School, we take a closer look at where this yield is coming from with Purdue University agronomy professor Dr. Tony Vyn. No doubt good growing conditions were a key contributor to the big crop, but in recent years more evidence is pointing to how higher kernel weight is boosting yield.

In his presentation earlier this month at the Ontario Agricultural Conference, Vyn noted that hybrid research over the past 30 years suggests that two-thirds of the yield increase growers are now experiencing can be attributed to higher kernel weights, when hybrids are compared at optimum plant density. He added that one-third of yield increases result from higher kernel numbers.

In the video, Vyn looks at what factors contribute to higher kernel weights throughout the growth and development of a corn plant. He notes that potential kernel weight is determined during the lag phase of development (R1 – R3). The plant then enters a linear phase where steep grain accumulation and a long grain fill period combine to produce heavier kernel weight.

When it comes to management factors that impact kernel weight, Vyn emphasizes that adequate amounts of water and sunlight are most important. Then, during the lag period, it’s essential that nitrogen is highly available to the plant as well as a good balance of other nutrients including sulphur, phosphorus, and micronutrients such as zinc.

The key element, however, is nitrogen but he emphasizes that there really is no optimum rate. With so many factors impacting plant growth it’s difficult to peg a specific rate. But there are some clues growers can pick up to determine whether the plant has sufficient nitrogen. (Story continues after the video.)

“It’s been our experience that we tend to get the best possible potential kernel weights when our leaf nitrogen concentrations going into (the lag) period are about 3 per cent nitrogen,” says Vyn. These levels can be measured in the ear leaf, but growers will need to modify their management to include tissue testing at the V12 stage, before flowering, in order to evaluate leaf tissue nitrogen sufficiency.

Vyn also advises growers to learn as much as possible about the hybrids they plant. He notes that all hybrids will ‘flex’ and increase or decrease kernel numbers and weights depending on management and growing conditions. “It is helpful if growers know which hybrids flex the most in terms of kernel weight and learn as much as possible from seed suppliers about the opportunity for a hybrid to achieve increased kernel depth or length under optimum conditions.”

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