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Effects of early-season drought stress on corn

June 28, 2016

While some areas in the U.S. had adequate rainfall, others experienced hot, dry weather for most of June. Scattered rain and more rain chances in the future have brought some relief to the corn fields, but growers are wondering if the early-season heat and drought stress have affected the yield potential on their corn.

Effects of drought on the corn plant

  • Leaves roll up. (Pictured above). Leaf rolling helps to conserve water by reducing the surface area of the leaf exposed to sunlight. This comes at a cost to the plant, however, as it will reduce photosynthesis, which in turn can affect the overall plant size and reduce yields.
  • Root growth is affected. Dry soils cause the root tips to desiccate and stop growing. It will also cause brace roots to grow along the surface instead of penetrating the dry soils, which can lead to standability issues later in the season. The decrease in root growth also limits the amount of root surface area that is available to collect nutrients and water from the soil solution. This can lead to a reduction in overall plant growth if conditions don’t improve.

poor root development

Poor root development and brace roots growing on the soil surface due to dry soil conditions.

  • Reduced nutrient availability. Drought conditions reduce the soil moisture and available nutrients in the soil solution. Potassium (K) availability is reduced as the soil dries, and can become tied up in soils with heavier clay contents. Fields that have adequate K levels will help to increase the drought tolerance for the corn plants. K-deficient corn will compound the stresses brought on by drought.

potassium deficiency

Potassium deficiency in corn. Note the firing running down the leaf margins.

Early-season drought stress and yield potential

Drought stress during the vegetative growth stages is generally less detrimental to yield than stress during pollinations and grain fill. That being said, it can still result in kernel loss and yield reduction, as there are important developmental processes taking place in the plants. Corn that is rolled up for a couple of days likely won’t see any significant yield loss, while corn that is rolled up most of the day for two weeks may see yield losses up to 20 percent. Actual yield reduction will vary greatly and depend on the severity and duration of the drought stress.

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Submitted by Scott Gard, Syngenta agronomic service representative, and Bob Lawless, Syngenta product development agronomist.

Photos are either the property of Syngenta or used under agreement.