Every abundant harvest begins with something small—a single maize kernel. Though tiny, this seed carries the full potential of an entire season. Its role, however, is limited to one crucial phase: germination. What happens beyond that point lies in the hands of nature and the farmer. While a strong start doesn’t guarantee a successful season, without it, success is simply out of reach.
When it comes to the maize seed’s contribution to harvest success, two factors are crucial: the genetic potential of the hybrid, and the emergence performance of the kernels themselves. Each maize kernel is essentially a dormant embryonic plant with the potential to produce up to 800 new kernels on a single cob. High yields are therefore achievable—provided the growing conditions are right.
The maize kernel’s role is limited to the germination phase. Once it has successfully germinated, environmental conditions and farming practices take over in determining the final yield. At that point, the seed has done its job.
After germination, the seed no longer influences the plant’s further growth, cob size, health, or yield. The rest of the season’s success depends on factors such as:
- Soil moisture
- Soil fertility (fertilization)
- Environmental factors (e.g., rainfall, pests, etc.)
- Flowering and pollination conditions
Germination is one of the most critical phases in a maize plant’s life – without it, there is no plant. It is therefore essential to understand, support, and protect this process from stress factors.
Important Physiological Processes During Germination
There are four important steps for successful germination:
- Imbibition (the absorption of moisture)
- The breaking of seed dormancy
- Development of the radicle (embryonic root)
- Growth of the mesocotyl (which is responsible for the upward movement of the coleoptile)
These steps are regulated by complex physiological processes influenced by temperature, as well as specific elements, minerals, and plant hormones. In his 2017 article, Getting Germination Off to a Good Start, Tyler Steinkamp (crop protection manager at Winfield United in Marion, Iowa) provides an insightful summary of these processes:
- Imbibition (Rehydration)
The moisture content of the kernel increases from about 12.5% to 35% within 24–48 hours after planting. Water must be warmer than 10 °C. The kernel then begins producing gibberellic acid, which converts starch into sugars to stimulate growth. - Phosphate Uptake
Phosphate is essential for energy transfer and DNA production. Sugars are converted into energy, and phosphate helps transport this energy to areas of cell elongation and growth. - Zinc Uptake
Zinc works closely with phosphate and plays a key role in converting starch to sugar and in producing auxins – a hormone important for cell elongation and division. It also stimulates leaf development, which forms the plant’s “solar panels.” - Cytokinin Production
This hormone is important for cell elongation and differentiation. Without cytokinin, there is no signal for cells to multiply, divide, or differentiate into the various parts of the plant, and roots and stems cannot develop properly.
Although the farmer cannot change the genetics of a chosen hybrid, by understanding the above critical steps, they can optimize germination conditions.
Practical Tips for Successful Germination
Here are practical guidelines to support the germination process of your maize kernels – ensuring a strong start that lays the foundation for a successful harvest.
Planting Depth and Soil Temperature:
Plant maize kernels between 7–8 cm deep. Shallow planting, especially in cold conditions, delays germination. Deeper planting depths offer more stable soil temperatures, which are favorable for successful emergence.
In cold conditions, seed cells lose elasticity and burst during imbibition – known as imbibitional chilling injury. This prevents further germination. A corkscrew-shaped mesocotyl indicates successful germination but chilling injury in the mesocotyl tissue afterward.
Testing soil temperature at planting depth before planting is crucial. If it’s below 10 °C and cold is expected within 48 hours, delay planting until more favorable conditions prevail.
Favorable Moisture Conditions
Seeds should be planted in moist soil, but be cautious – excessive wetness can displace oxygen from the soil and suffocate the plant. Watch for signs of suffocation.
Phosphate and Zinc Application
As explained in the germination steps above, maize kernels need both phosphate and zinc to germinate and develop successfully.
Phosphate:
- Can be applied on or below the kernel.
- Use banded phosphate that doesn’t cause fertilizer burn.
- Apply phosphate alone, not bound with salt.
- The finer the phosphate, the better the uptake.
Sink:
- Zinc must be fully chelated for effective uptake, especially in high pH soils.
- Apply early in the season to new leaves.
- Zinc deficiency appears as broad, striped leaf bands and delayed growth in the first three weeks.
Plant Growth Regulators
The plant produces its own hormones, but additional application of auxins, gibberellic acid, and cytokinins can accelerate emergence and improve early vigour.
Conclusion
The maize kernel may be small, but its role in the success of a harvest is significant – and time-limited. By thoroughly understanding and practically supporting the germination process, producers can ensure the best possible start for their crop. Strong emergence lays the foundation for a healthy plant and a high-yielding season.
By Klaas van Wyk, Regional Agronomist for the Northern Cape, Pannar Seed
