5 SCIENTIFIC REVIEW, CROPS
5.2.5 Barley, wheat and oats
Cropping practice and use in Denmark
Barley (Hordeum vulgare) and wheat (Triticum aestivum) are among the most extensively grown crops in both North West Europe and the world in general. In Denmark, barley and wheat occupy the largest part of the total arable area, whereas the area of oats (Avena sativa) is small by comparison. Altogether the three cereals are grown on approx. 1.43 million ha or approx. 50% of the Danish cultivated area, and they constitute a very important part of the supply of feed for Danish livestock production and to a lesser extent for human food. Due to the wide distribution of these crops in nearly all regions of Denmark, these three cereal crops have a significant impact on the landscape and environment.
Crop area, Denmark, 2002 and 2006 (Rounded figures)
Year of cultivation 2002 2006 Conventionally grown barley for production 770,000 ha 633,000 ha Conventionally grown barley for seed 39,000 ha 36,000 ha Conventionally grown barley in total 809,000 ha 669,000 ha Organically grown barley for production 17,000 ha 9,000 ha Organically grown barley for seed 3,000 ha 1,000 ha Organically grown barley in total 20,000 ha 10,000 ha
Barley in total 829,000 ha 679,000 ha
Year of cultivation 2002 2006
Conventionally grown wheat for production 550,000 ha 656,000 ha Conventionally grown wheat for seed 24,000 ha 23,000 ha Conventionally grown wheat in total 574,000 ha 679,000 ha Organically grown wheat for production 7,000 ha 7,000 ha Organically grown wheat for seed 1,000 ha 1,000 ha Organically grown wheat in total 8,000 ha 8,000 ha
Wheat in total 582,000 ha 687,000 ha
Year of cultivation 2002 2006
Conventionally grown oats for production 43,500 ha 48,000 ha Conventionally grown oats for propagation 2,500 ha 2,300 ha Conventionally grown oats in total 46,000 ha 50,300 ha Organically grown oats for production 7,700 ha 9,900 ha Organically grown oats for seed 800 ha 500 ha Organically grown oats in total 8,500 ha 10,400 ha
Oats in total 54,500 ha 60,700 ha
Sources: Kristensen, 2007; The Danish Plant Directorate, 2006b.
In 2006 the cereal area had decreased by approx. 2% from the 2002 area; however, this includes a decrease of 18% in the barley area and a corresponding increase of the wheat area of 18%. The area of oats, which is much smaller, increased by approximately 11%. The organic area covers approx.
2.2% of the area of cereal crops.
In addition, cereals are grown alone or in mixture for whole-crop silage on approx. 58,000 ha conventionally and approx. 11,000 ha organically. However, the areas for this purpose are decreasing (rye and triticale is discussed in section 5.2.7).
Experience with GM cereals in Denmark
There is no experience as yet with growing genetically modified varieties of these cereals in Denmark, but several types of genetically modified wheat and barley were developed at the Faculty of Agricultural Sciences at the University of Aarhus, and they are expected to be tested in field trials in the years to come.
Experience with GM cereals outside Denmark
In the EU, a total of 31 releases of GM wheat have been recorded, chiefly wheat with improved resistance to fungi, especially Fusarium, improvement of baking quality and nitrogen exploitation, fertility, modifications in the starch synthesis and some types of herbicide tolerance. For GM barley, a total of 6 releases have been recorded in the EU with improved resistance to fungi and improved malting ability as well as for use in model systems for studying gene dispersal (JRC, 2007 a & b). Some of the releases are tolerant to herbicides. In North America, Monsanto in particular has worked on a glyphosate tolerant GM wheat, which was approved in 2004, but which has not been marketed since then (AGBIOS, 2006). Thus, there is still no experience either worldwide or in Europe with growing GM cereals, only results from trial releases.
Sources of dispersal
Barley, wheat and oats are generally highly self-pollinating, which means that their gene dispersal is weak through cross-pollination. Their possibility of gene dispersal through cross-breeding with wild relatives is also very limited in Denmark, and they do not generally survive for a long time as volunteers.
New knowledge
Barley, wheat and oats are traditionally considered to be predominantly self-fertilising because they flower with closed flowers. Gene dispersal through cross-pollination is therefore considered to be very low, and conventional seed production from these species does not use isolation distances as such, only separation in the form of boundaries or the like.
Cross-pollination between dense wheat plants has previously been reported to be 0-6% (Martin, 1990; Hucl, 1996). Corresponding cross-pollination frequencies between 0 and 7% between dense plants were reported for barley (Abdel-Ghani et al., 2004; Parzies et al., 2000; Ritala et al., 2002).
Studies of cross-pollination between fields in Canada showed that wheat pollen can cross-pollinate at distances up to 300 m from the source of pollen, but that the cross-pollination frequency between plant populations decreases very rapidly with distance into the receptor. Receptor plants approx. 20 cm from the pollinator showed 0.2 and 0.08% cross-pollination respectively in the two trials, whereas the cross-pollination frequencies one metre inside the receptor plot were 0.17 and 0.06%, and cross-pollination frequencies decreased very quickly with distance into the receptor. A field just
one metre wide without any isolation distance from the pollinator was below the 0.9% in both trials (Matus-Cádiz et al., 2004).
Hansonet al. (2005) achieved comparable cross-pollination frequencies with three different receptor varieties. Cross-pollination frequencies in the receptor quite close to the pollinator were below 0.1%, and simulation studies have resulted in similar conclusions (Gustafson et al., 2005).
In recent field trials in Australia with barley and wheat, cross-pollination from GM plots into adjacent non-GM wheat and barley was measured. In one trial with GM wheat grown at a distance of one metre from the surrounding trap crop, a cross-pollination frequency of 0.012% was found.
With plants grown 40 cm from each other, cross-pollination was 0.055%. In another Australian study with wheat and barley, comparable low cross-pollination frequencies of 0.0037% for wheat and 0.005% for barley were found (Gatford et al., 2006).
Seed dropped at harvest may germinate in a succeeding crop providing a source of gene dispersal, especially if the succeeding crop is of the same species. A recent review of literature concerning the ability of wheat seeds to survive and germinate (Anderson & Soper, 2003) supports previous knowledge on the subject. Most volunteer wheat seeds die within the first year, but some may survive considerably longer in the soil, up to 2 years (Anderson & Nielsen, 1996).
It has become clear that wheat hybridises with a wide range of wild relatives belonging to Triticum andAegilops that occur in wheat growing areas in Europe (Zaharieva & Monneveux, 2006).
However, none of these species is distributed in Denmark, and their cross-pollination frequencies with wheat are so low that they can hardly act as genetic reservoirs for cross-breeding back into other crops. They may become a problem as weeds if for example herbicide resistant genes are transferred from wheat to these species.
Measures
The most important measures in these species are the supply of seed with no GM content, as gene dispersal with pollen is very limited and survival of volunteers is relatively small. For the production of seed, no proper isolation distance is set out between fields with barley, wheat and oats; however, a clear separation or boundary is required. Based on the most recent knowledge in the area, there ought to be an isolation distance of one metre to fields with non-GM crops of the same species when GM crops of the three species are grown. This corresponds to a clear boundary.
For seed production of these 3 cereals, a cropping interval of 1 year is used before seed production of the same species on the same area to avoid transfer of genetic material between the varieties as a result of seeds that are shed during the first year and then germinate and develop in the next crop.
This 1-year cropping interval is also recommended in this evaluation as the time needed to pass from growing one GM crop to a non-GM crop of the same species to avoid significant transfer of GM material to the next crop. This cropping interval is still considered sufficient provided that effective control of volunteers is carried out.
Need for further knowledge
More knowledge about cross-pollination frequencies between fields of barley, wheat and oats, especially under Danish conditions, would still be useful. Furthermore, the problems concerning volunteers are inadequately explained for all species under Danish growing conditions. There is a special need for simple and effective instructions on the control of volunteers.
Conclusion
The cereal areas in Denmark are almost unchanged since 2002, and they comprise approx. 50% of the total cultivated area; however, there has been a shift so that the barley area has decreased by approx. 18%, which corresponds to an increase in the wheat area of approximately 18%. The wholecrop areas have been significantly reduced. The organic area is approx. 2.2% of the cereal area.
Based on the most recent knowledge in the area, we propose that for GM crops of barley, wheat and oats an isolation distance of one metre should be kept to fields with non-GM crop of the same species; this corresponds to a clear boundary.
To sum up, the same conclusions are made as in the 2003 Report. These species show very little dispersal of their genes, so that ensuring against GM content in seed is the most important measure to achieve co-existence for these species.
Knowledge about cross-pollination frequencies under Danish growing conditions is still needed, just as the problems concerning volunteers are inadequately studied.
5.2.6 Triticale
Cropping practice and use in Denmark
Triticale (Triticosecale spp) is often spoken of as a man-made cereal, as it was developed from cross-breeding between wheat and rye during the past 50 years. Thus, triticale combines some of wheat’s advantages as a feed with some of rye’s ability to perform in soils where wheat normally does not thrive. In Denmark, triticale is mainly grown as a winter crop, mostly on sandy soils in West Jutland, and it is used almost exclusively for feed, while it is also used in some parts of the world as a component in bread. The total triticale area in Denmark comprises approx. 27,000 ha grown conventionally and approx. 4,000 ha grown organically.
Crop area, Denmark, 2002 and 2006 (Rounded figures)
Year of cultivation 2002 2006
Conventionally grown triticale 24,000 ha 26,200 ha Conventionally grown triticale seed 1,000 ha 1,100 ha Conventionally grown triticale in total 25,000 ha 27,300 ha Organically grown triticale 1,900 ha 3,700 ha Organically grown triticale seed 400 ha 600 ha Organically grown triticale in total 2,300 ha 4,300 ha Triticale in total 27,000 ha 32,000 ha Sources: Kristensen, 2007; The Danish Plant Directorate, 2006b.
The triticale area has increased by approx. 18% in the years 2002 to 2006; of this the organic area is approx. 14%.
Experience with GM triticale in Denmark
There is no experience as yet with growing genetically engineered varieties in Denmark.
Experience with GM triticale outside Denmark
There is no experience as yet with growing GM varieties of triticale in Europe or the rest of the world, but GM types are being developed for research purposes in a number of laboratories worldwide.
Sources of dispersal
Triticale is considered to be more open-pollinating than barley, wheat and oats, and therefore there is an increased likelihood of gene dispersal by pollen. Just as for wheat, barley and oats, the possibilities of gene dispersal from triticale to wild relatives through cross-breeding are very limited, and volunteers do not generally survive for long in the soil.
New knowledge
Triticale is more open-flowering than barley, wheat and oats and has higher cross-pollination frequencies. Therefore, an isolation distance of 20 metres is maintained between seed fields during production of triticale seed. There are no good studies for triticale of cross-pollination frequencies and gene dispersal into neighbouring fields.
Just as wheat is known to hybridise with a wide range of wild relatives within Triticum and
Aegilops, which are widespread in wheat growing areas in Europe (Zaharieva & Monneveux, 2006), it must be assumed that some types of triticale will also be able to cross-breed with these species.
However, none of the species is widespread in Denmark, and their cross-pollination frequencies with triticale are probably so low that they can hardly act as genetic reservoirs for cross-breeding back into other crops. They may become a problem as weeds if for example herbicide resistant genes are transferred from future GM triticale to these species.
Measures
The most important measures will still be ensuring against GM content in seed, isolation distances as well as cropping intervals and control of volunteers.
Triticale can be more cross-pollinating than wheat, barley and oats, and in seed production of triticale a separation distance of 20 metres is maintained to other triticale fields. This separation distance to other fields with the same species should also be observed if GM triticale is grown in the future.
In connection with seed production of triticale, a cropping interval of 1 year before seed production of the same species on the same area is used to avoid transfer of genetic material via volunteers resulting from seed shed during the first year which germinate and develop in the next crop. This 1-year cropping interval is also recommended as the time needed between growing one GM crop and a non-GM crop of the same species in order to avoid significant transfer of GM material to the next crop. This cropping interval is considered sufficient provided that effective control of volunteers is carried out.
Need for further knowledge
There is a general lack of knowledge about cross-pollination frequencies and gene dispersal between triticale fields.
As for barley, wheat and oats, the problems concerning triticale volunteers under Danish growing conditions are inadequately studied. There is a need for a simple and effective means of controlling volunteers so that they are not incorporated into the soil seed bank.
Conclusion
The triticale areas have increased a little since 2002 but are still only approx. 30,000 ha in Denmark.
Triticale cross-pollinates more than wheat, barley and oats. We propose that the 20 m separation distance from a GM triticale field to a conventional or an organic triticale production field should remain unchanged.
We propose that the cropping interval between growing a GM triticale to growing conventional or organic triticale for production should remain 1 year, i.e. unchanged.
Ensuring purity of seed will be the most important measure for co-existence for triticale.
We lack knowledge of cross-pollination frequencies and gene transfer and lack knowledge to understand problems with volunteers.
5.2.7 Rye
Cropping practice and use in Denmark
The cultivation of rye (Secale cereale) has halved since 2002 and in 2006 is 0.9% of the cultivated area. However, organic growing is almost unchanged and is approximately 11% of the total rye growing in 2006. Growing for wholecrop has almost ceased.
Crop area, Denmark, 2002 and 2006 (Rounded figures)
Year of cultivation 2002 2006
Conventionally grown rye (ripe grain) 42,400 ha 25,100 ha Conventionally grown rye (wholecrop) 6,000 ha 100 ha Conventionally grown rye for seed 1,600 ha 500 ha Conventionally grown rye in total 50,600 ha 25,700 ha Organically grown rye (ripe grain) 2,500 ha 2,550 ha Organically grown rye (wholecrop) 2,300 ha 50 ha Organically grown rye for seed 500 ha 350 ha Organically grown rye in total 5,300 ha 2,900 ha
Rye in total 56,000 ha 29,000 ha
Sources: Kristensen, 2007; The Danish Plant Directorate, 2006b.
Experience with GM rye in and outside Denmark
As far as the Working Group is aware, there have been no trial releases of GM rye from 2003 to now, but scientific papers on genetic engineering are available.
Sources of dispersal
Rye is both cross- and wind-pollinated, and pollen can be dispersed with the wind over large distances. Normally, the seeds survive less than one year in the soil. There are no weeds or cultivated plants in Denmark with which rye can cross-breed.
New knowledge
A computer model has been developed under the research programme DARCOF II in order to calculate wind dispersal of GM pollen from rye to other fields in the landscape
(Geelset al., 2004). In addition to the meteorological data, the dispersal model includes the flowering period of the crop and physical parameters for the pollen for calculations of the dispersal.
National proposals for rye co-existence
The Danish proposal in the 2003 Report was a separation distance of 250 m for winter rye and 500 m for rye hybrids.
The Finnish report “Enabling the Co-existence of Genetically Modified Crops and Conventional and Organic Farming in Finland” proposes 300 m for winter rye and 500 m for rye hybrids (Ministry of Agriculture and Forestry, Finland 2005).
Measures
The measures are ensuring against GM content in seed, separation distances, cleaning of harvest machinery and buffer zones consisting of maize or conventional rye.
Need for further knowledge
As stated in the 2003 Report, we lack knowledge about the dispersal of rye pollen under Danish conditions and studies of the effect of different field sizes and shapes.
Conclusion
The area of rye has halved since 2002 and in 2006 is 0.9% of the cultivated area. However, organic growing is almost unchanged and is approx. 11% of the total rye growing in 2006.
As far as the Working Group is aware, there have been no trial releases of GM rye from 2003 to now.
The Working Group proposes that the separation distances proposed in the 2003 Report of 250 m for common rye (non-hybrids) and 500 m for rye hybrids should be maintained. As in the case with the other cereals, the cropping interval should be 1 year.
There is considerable uncertainty and limited experience regarding cross-pollination between GM rye and conventional and organic rye respectively; therefore, the Working Group does not think that there is scientific justification for changing the proposed separation distances at present.
Studies are needed of rye pollen dispersal under Danish conditions and of the effect of different field sizes and shapes.