Oat Types and Classifications

Oat Types

Winter Oat

Like winter wheat, they have a vernalisation requirement. This is the need to experience a period of cold which enables the plant to flower. The vernalisation requirement is typically half of that of wheat i.e. 20-25 days compared to 50 days. This is known as the effective days to saturate the response to vernalisation. If drilling is delayed and the vernalisation period is limited a delay in flowering can be expected.

Winter oats are typically sown from mid-September to October and harvested the following August (Northern Hemisphere). Oats are often drilled in the first half of October after OSR and wheat drilling is complete. Crops drilled in mid-September achieved the highest yields. As with other cereal crops there are disadvantages and advantages to earlier drilling. Earlier drilling increases risk of disease such as mildew getting established in the autumn especially if the crop is thick. It also means the crop will be emerged in October and early November when aphids are still active increasing the risk of virus infection. Thicker early drilled crops present a greater lodging risk as a result of better establishment and early autumn growth but this can be managed with lower seed rates.

An advantage of getting the crop established earlier is that a well-established crop has put down a good root system which gives resilience to frost lift. A well rooted crop will also be less susceptible to transient nutrient deficiencies (such as Manganese) that is more common in cold winters.

In summary: 

• Wide autumn drilling window: Mid-September to November. 
• Optimum drilling date: Mid-September to Mid-October. 
• Earlier drilled: 
  • Higher yield potential and more resilient to frost lift 
  • More susceptible to autumn pests and diseases, higher lodging risk.

Spring Oat

In contrast, spring oats do not require cold temperatures (vernalisation) to trigger flowering and thus can be sown when soil conditions are appropriate. The growing season varies between 150 days to 180 days depending on the climate. Spring Oats can be sown fairly early in the spring as soon as the soil is dry enough for cultivation. Early sowing helps the seeds utilize the moisture in the soil. Germination will occur at about 3-5oC, which shows that they resist the coldness of the early growing season.

Oat Classifications

Common Oat (Avena sativa L)

Common oat is the most important of the cultivated oats. All varieties are characterized by a panicle/spike that is pyramidal in shape with equilateral branches that spread outward. Many varieties are awnless, and in awned varieties, usually only the first flower is awned. Lemmas and paleas surround the grain/kernel and may be white, grey, yellow or black in colour.

Red Oat (Avena byzantina.)

A number of important cultivated varieties of both winter and spring habit are included in red oats. The two flowers in the spikelet adhere tightly to each other and separate by fracture of the stem at the base. The lemmas surround the kernel and have weak, non-twisted awns. Stems are usually slender and rather stiff and reddish in colour. Panicles/spikes are small, narrow and upright with relatively few spikelets. Red oat varieties are the kinds generally grown in the southern half of the United States. This type is also grown in the near and middle east.

Large Naked Oat (Hull-less Oat).( Avena nuda L.)

In this species the kernel / grain is loose within the hull/palea as in wheat. The origin of the species appears to have been Central and Eastern Asia. Several varieties have been introduced, but they are grown only to a very limited extent.