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Causes of Germination Failure in Cereal Crops – Part 1: The Importance of Seed Quality

Materials, Chemistry & Biology
Crop germination failure

Germination failure for farmers can be expensiveIt is not just the cost of the seed but the field preparations and operations before and after the crop failure that need to be taken into account should a failure occurThese include:  

Added to these will be the loss in yield at harvest because later autumn sowings have lower establishment rates and spring-sown crops yield less than autumn-sown crops.  Therefore, farmers could justifiably include all these additional costs if they are making an insurance claim. 

The variation in establishment of cereal crops ranges nationally from 2 to 100% according to research data gathered between 1977 and 2002 (Blake et al, 2003).  On average it is around 67%, but the expected percentage for wheat, for example, should be 85%.  The reason for the actual figure being much lower in commercial practice may be because experimental work done to determine germination is usually sited in the better areas of fields and receives greater care and attention than many commercial crops would.  I describe below some of the other reasons for poor establishment:  

Unloading grain in a grain store

Whether certified or farm-saved[1], it is important to understand the quality of seed. By law, seed must be officially sampled and tested before it can be certified. Sampling and testing are also important for grain intended for farm-saved seed, although it is not compulsory.  Seed certification schemes protect farmers and their customers by guaranteeing that all UK certified seed meets prescribed standards for varietal identity and purity, germination and freedom from foreign materialSampling and testing determine the cleanliness of the seed and the viability, but if not completed close to the sowing date may impact the  accuracy of the results.  Tests performed by the seed testing laboratory should include:  

The grain drying process

Seed Storage

Seed moisture content and storage temperature are critical to maintain quality over the storage period. Generally, wheat seed with a moisture content of 12%, stored at 20°C for a period of 360 days, will retain about 92% germination. However, seed with a moisture content of only three percentage points higher, will result in a mere 27% germination. 

Ideally, seed should be stored around 10°C, but the availability of such facilities for bulk storage is limited. The viability of grain deteriorates faster when stored at high temperatures, especially above 20°C.  Storage facilities may not be able to keep the temperature below 20°C, especially in the summer months, and with hotter summers as a consequence of climate change, cooled seed storage facilities may become necessary in the future. 

The growth and reproduction of moulds and pests is also influenced by temperature and moisture content.  Storage fungi can grow above moisture contents of 14.5% on cereal grain and 7.5–8% oilseed rape seed. The activity of each fungal group depends on a combination of moisture content and temperature.  These include the following: 

The activity of four fungal groups at various temperatures and moisture contents. A = Aspergillus species; B = Penicillium species; C = Fusarium and related species; D = Thermophilic fungi

Pests are adapted to the grain storage environment. They can breed at relatively low temperatures and moisture contents. A single insect per kilogram of grain could represent a potentially serious infestation.   

Maintaining good hygiene in the store helps reduce insect populations as storage pests can survive on grain residues from the previous harvest and will infest new grain as it is placed into the store.

Common primary species include: 

Seed Treatment

Seed is usually treated with fungicide or insecticide by specialist contractors after storage and before sowingSeed should be cleaned to remove impurities such as chaff, weed seeds, soil particles and dust, otherwise the seed treatment will adhere to these instead of the seed. 

Dirty wheat seed (left) vs clean seed (right) (source: Bayer).

It is important that the treatment is mixed correctly and applied at the proper rate.  Products from well-known agrochemical companies are more expensive, but will be better in the long run because cheaper, inferior products can become lumpy, separate in solution and stick to equipment rather than seed, making them difficult to use. 

The products are usually coloured.  An even colour all over the seed indicates that the coating has been applied properly, but a patchy appearance indicates it has not and could be a result of poor seed quality, dirty seed, poor product quality or incorrect dilution. 

Patchy colouration on poorly treated barley seed (left) compared to even colouration on well treated seed (right) (source: Bayer).

Part 2: Soil and Sowing covers seedbed preparation, sowing operations and environmental conditions.  This will be published next month.

[1] When harvested seeds from cereals or oilseed rape are used to establish a subsequent crop, it is called farm-saved seed (FSS). Farm-saved seed differs from officially certified seed, which meets specific conditions and controls for sale – relating to, for example, germination capacity, varietal identity/purity and contaminant levels.

About the Author

James has over 20 years’ experience in his field, and is experienced in investigating the causes of plant diseases, crop failures and spoilage of fresh produce.

He has worked on projects to breed genetic resistance to diseases in oilseed crops and published research into the effects of climate change on plant diseases in the UK. James has also managed a portfolio of field and glasshouse research projects, gaining extensive experience in plant disease diagnostic techniques.

James joined Hawkins after four years at Berry Gardens Growers, the UK’s leading berry and stone fruit cooperative. During his tenure, he set up the plant disease diagnostic laboratory, and used his expertise to diagnose crop problems and fruit rots and advise growers on disease management strategies.

James is a Senior Associate based in our Reigate Office and has investigated cases of crop germination failure, crop storage problems, fallen trees, mould contamination, pesticide damage, wildfires and plant disease outbreaks in domestic and commercial settings.

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