As the calendar marches forward and temperatures continue to rise, planting begins. Planting plays a critical role in influencing seed germination and emergence. It can even impact yield at the end of the season.

For these reasons, it’s important to review some of the key requirements to ensure planting, germination, and emergence are a success. 

 

Priority of the Planter Pass & Conditions at Planting

The goal of the planter is to ensure uniform seeding depth, spacing, and seed-to-soil contact.

 

Planting Depth

For corn, seeds are planted around 2” deep. If corn is planted shallower than this, the nodal root system will not develop at the ¾” soil depth. This can lead to a poorly developed root system that can’t adequately access water and nutrients for the plant, as well as a root system that can’t physically support the plant.  

In some extreme cases, corn plants with a shallow root system can develop rootless corn syndrome early in the season. This impacts the growth and development of the crop for the remainder of the season.

Additional seeding depths for many of the crops grown in the Corn Belt are shown in Table 1.

Table 1

Table 1: Suggested planting depths and minimum soil temperatures for planting.

Soil Temperature

Prolonged exposure to soil temperatures below certain minimums (50°F for many crops) after planting affects the germination process. It and can leave the seed susceptible to attack from early season diseases and insects.

For example, cold stress in corn can result in imbibitional chilling injury and delayed and uneven emergence.

Table 1 includes suggested minimum soil temperatures for planting various crops in the corn belt. Current 4” soil temperatures can be found through your local university mesonet.

 

Soil Moisture

Adequate soil moisture at planting is key to successful germination and emergence. In some dry soil conditions, increasing the planting depth may be appropriate to ensure moisture is available for the germination process. 

 

Other Factors

There are numerous non-environmental factors that impact germination and emergence.

  • Seedbed preparation
  • Seed-to-soil contact
  • Seeding rate
  • Variety selection
  • Row spacing
  • Seed quality
  • Seed treatment
  • Use of starter fertilizers or biostimulants

These all impact the speed and success of the process.

 

The Germination Process

The first 24-48 hours after planting are critical for germinating seeds. Stress during this time can reduce viability of the seed, increase the length of time for emergence, and increase the chances for infection from seedling diseases.

The germination process includes several components.

  • Imbibition of water: during this time, seeds take in 30-50% of their weight in water. 
  • Hormone production: imbibition of water triggers the production of growth hormones which signal to the seed to produce alpha-amylase, an enzyme that begins to remobilize nutrients stored in the endosperm of the seed.  
  • Phosphorus: this key nutrient provides the energy to drive the germination of the seed.  
  • Zinc: this key nutrient helps with enzyme activation during germination.  

Starter fertilizers and other products applied at planting help to address these needs during germination. They do this by supplying seeds with additional nutrients, hormones, or biostimulants to help drive the process.

 

The impact of delayed and uneven emergence

Delays during stand establishment can impact the crop for the remainder of the season. At an average soil temperature of 50°F it takes corn plants around 20 days to reach 50% emergence. That’s a long time for seeds to survive prior to emergence!  

 

Example of delayed emergence’s impact on yield

University researchers in Wisconsin and Illinois conducted a 2-year study to evaluate the effect of delayed emergence on yield. They found that delaying corn emergence by 1½ weeks reduced yield by 5% (Figure 1). Delaying emergence by 3 weeks reduced yield by 12%.

Figure 1

Figure 1: Results from a 2-year study evaluating the effect of delayed emerging plants on end of season corn yield. (Source: pioneer.com; Adapted from: Nafziger, Carter and Graham, Crop Science 31: 811-815 (1991)).

However, most stands contain a mix of early and late emerging plants, which can impact yield by as much as 20%! Planting into soils with adequate moisture and the proper temperature helps to maximize the crop yield potential from day one.

 

Product Solutions

Table 2 highlights several Innvictis product options at planting that supply nutrients, plant growth hormones, or biostimulants to aid with germination and emergence.

Table 2: INNVICTIS® product reccomendations

 

Table 2: INNVICTIS® product reccomendations

 

The Takeaway

  • The first 24-48 hours after planting are critical to avoid chilling injury of the seed.
  • Early planted crops that experience delays in germination and slowed growth rates may be more subject to damage from insects and diseases. In addition to uneven emergence and reduced yield.
  • Waiting until average soil temperatures in the seed zone are above the recommended minimum (50°F for many crops), and having a favorable two-day forecast helps alleviate the potential risk of germination issues.

Please consult any of your local Agronomy Sales Enablement Team or your local Simplot Grower Solutions Crop Advisor to answer your application questions.

Authors

Brice Bunck, Midwest
Kevin Caffrey, Eastern Cornbelt
Chris Carpenter, Great Plains
Darrin Roberts, Northern Plains

Click to read more about the authors