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Corn Gromwell

A new oil crop for UK farmers, containing stearidonic acid (SDA), an omega-3 fatty acid from plants with the health benefit of fish oils

Contact: Steven Bentley

The Crop

Corn Gromwell  
Corn Gromwell commercial crop at NIAB

Corn Gromwell (Buglossoides arvensis) was a well known weed of spring cereals until the extensive use of winter varieties and herbicides. NIAB TAG in collaboration with Technology Crops have developed this weed species into a commercial spring cropping opportunity with the real probability that higher yielding winter lines will soon be available.

The market

SDA is a key precursor in the biosynthesis of long chain, omega-3, polyunsaturated fatty acids commonly found in fish oils. The health benefits of fish oils are generally well accepted and therefore with an aging population and a declining consumption of fish products alternative sources of these fatty acids are needed for inclusion in the diet. Croda have been working with Corn Gromwell using their extraction technology to develop the next generation of products after Echium oil.

Economics for farmers

Currently Echium is the only commercial non-GM plant source of SDA.

Gross margin estimations for Spring Cropping in 2011 show that Echium plantagineum would be the second most profitable farm crop.

Corn Gromwell Margins

However, Echium is a crop that needs specialist harvesting equipment and due to its tendency to shed seed as it matures and needs a high level of management input to ensure maximum yields. These factors restrict the growing of Echium to a few specialist growers, but also ensures that high crop prices are paid to those growers.

Buglossoides arvensis is a more ‘farmer friendly’ crop. It can be allowed to senesce (mature) naturally and then be harvested as a standing crop. It holds on to its seed very tightly so seed loss at harvest is minimal. Management input and variability are significantly reduced.

Trials and small commercial test crops indicate a yield of 0.75 – 1.0 t/ha are achievable.

NIAB TAG and Technology crops have developed a complete agronomy package for this new crop. This will minimise the risk to any grower trying the crop for the first time. We have completed trials for:- seed rates (fig 1), planting dates, nitrogen rates (fig 2), regional trials, herbicides and fungicides. The information developed during the project will be used to establish the 2011 trial series which will be available for demonstration.

Corn Gromwell
Fig 1 Sowing density trials: Medium pop, High pop, Low pop

Corn Gromwell
Fig 2 Nitrogen Application Rate Trials

Corn Gromwell needs to be established in the early spring at a similar timing to a spring barley crop but would be ready for harvest in June or July. The crop is therefore unlikely to clash with other crops for harvesting and provide a good entry into winter wheat. In addition to providing a new break crop for the rotation there will clearly be an opportunity to address any blackgrass issues and no residual weed problems in following crops.

Basic Agronomy of Corn Gromwell (Buglossoides arvensis)

  • Corn Gromwell is a spring drilled crop which is grown for the oil produced in the seed.
  • It is a member of the Boraginaceae family (others included Borage and Echium) so it is unrelated to other common farm crops,
  • Drilled early spring using standard farm equipment
  • Reaches maturity in July/August
  • Can be left to naturally senesce and direct combined or it can be swathed and harvested using a pick-up header
  • Low input crop, only needs about 50 kg/ha of Nitrogen depending on soil fertility
  • Range of SOLA’s available.
  • Low pest and disease pressure
  • Not palatable to pigeons or rabbits.
  • Leaves ideal, slug free, min-till entry for following wheat crop.

 

Clearance for food use

At present there is no novel food use or GRAS approval for oil from B. arvensis. However a successful application for a similar crop, Echium, has been made by Croda Chemicals Europe Ltd for refined Echium oil; stearidonic acid-rich oil from Echium. Whilst Croda consider that the market justifies the significant costs involved in such an undertaking, they are aware that this market is attractive and substitute products will be developed, especially if they provide the significant market advantage offered by Buglossoides. The commitment of this consortium to the development of the crop is therefore driving early discussions for commitment to get approval for novel crop use for B. arvensis.

Biochemistry of Fatty acids and Health implications

SDA is a key precursor in the biosynthesis of long chain (LC) omega-3 (or n-3) polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA, C20:5n-3) and docosahexanaenoic acid (DHA, C22:6n-3) that are commonly found in fish oils. Essential fatty acids is a term used to describe fatty acids which are needed in order to manufacture body lipids, biological membranes and hormone like substances such as prostaglandins, but which cannot be synthesised in the body and therefore must be obtained from the diet (Brooks, 1984, Newton, 1996). Only two fatty acids are truly essential, linoleic acid and alpha-linolenic acid, the remaining PUFAs are derived from these by a sequence of desaturation and elongation steps (Figure 1). Linoleic acid is the precursor for the omega-6 series of fatty acids which are found primarily in plant oils whereas alpha-linolenic acid is the precursor for the omega-3 series of fatty acids which occur mainly in green leafy vegetables and oily fish (Newton, 1996).

Corn Gromwell

Elongation and Desaturation of n-3 and n-6 PUFAs (after Newton, 1996)

The n-3 and n-6 fatty acids compete for the same enzymes in the synthesis of their respective long-chain PUFAs. Both series of essential fatty acids are the starting materials for the manufacture of a group of complex hormone like compounds known collectively as eicosanoids, which include the prostaglandins, leukotrienes, prostacyclins and thromboxanes. The eicosanoids have profound physiological activity even at extremely low concentrations. They are implicated in the functions of the nervous, cardiovascular and immune systems and can also affect the function of both the endocrine and exocrine glands.

The correct balance between the various eicosanoids is required in order to maintain good health. The ratio of omega-6:omega-3 fatty acids in the body is about 1:1 in the brain, 5:1 in fat tissue and 4:1 in other tissues (Erasmus, 1993). The levels of the eicosanoids can vary during different stages in the development of the body, with age and during the menstrual cycle. Delta-6-desaturase is the rate-limiting step in the synthesis of long-chain PUFAs; in addition, the activity of delta-6-desaturase is known to be inhibited by a number of factors, including diabetes, stress, excess saturated fats, high alcohol intake, smoking and viral infections. This can lead to deficiencies in the levels of the various essential fatty acids (Horrobin, 1995). The same enzymes are used to metabolise both the omega-3 and the omega-6 series of essential fatty acids and it is believed that the metabolites of alpha-linolenic acid will compete for these enzymes with the metabolites of linoleic acid. SDA conversion to EPA does not require this rate limiting step and feeding studies have shown an increase in the tissue levels of EPA.

The future

NIAB plant breeding and crop improvement.

NIAB have screened populations of Corn Gromwell collected from all the major agricultural areas of the world. As demonstrated in Fig xx we have found considerable variation in both the types and oil contents of the lines.

Using traditional selection techniques we have identified new and improved spring types and also of significant interest winter types. Winter types have the potential to be higher yielding and earlier to harvest. These new varieties are currently undergoing multiplication for full field scale testing. We are confident that these will deliver a significant increase in commercial value relative to what has currently been achieved.

Corn Gromwell
Fig 3 Genetic variation

Project Sponsors

Croda Chemical Europe Ltd

Technology Crops Ltd

MRC human Nutrition research

This project has been sponsored by DEFRA under the Sustainable Arable LINK programme.