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ANTH 2120
Eytan Lasry

Annals of Applied Biology ISSN 0003-4746 REVIEW ARTICLE Relevance of genetically modified crops in light of future environmental and legislative challenges to the agri-environment M. O’Brien & E. Mullins Plant Biotechnology Unit, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland Keywords Abstract Climate change; crops; EU environmental legislation; fertiliser; genetically modified;y challenge for countries like Ireland up to 2030 is to produce sufficient pesticides; traits. supplies of food, feed and fuel, without compromising on public health or neg- atively impacting the environment. As we progress through the technology era, Correspondence certain agricultural technologies [e.g. genetically modified (GM) crops] have E. Mullins, Plant Biotechnology Unit, Teagasc been championed to maximise production while minimising environmental Crops Research Centre, Oak Park, Carlow, impact. Yet, multiple arguments have been made to counter such a claim, which Ireland. Email: [email protected] has led to a polarisation of opinions and a plethora of generic commentaries being made in regard to the impact of this technology. Yet, few studies within Received: 26 June 2008; revised version the European Union (EU) have conducted a critical needs analysis to assess the accepted: 28 October 2008. potential of specific GM traits in light of issues, such as climate change, increased environmental legislation (e.g. EU Water Framework, Nitrates Directive, pro- doi:10.1111/j.1744-7348.2008.00304.x posed reform to the Pesticide Directive and Common Agricultural Policy reform), mitigating biodiversity loss and sustainable biofuel production. The goal of this study is to collate a register of GM traits such that a list of potential GM crops could be prioritised against the backdrop of the challenges facing the tillage sector. Clearly, the crops with the most significant potential for genetic modification are those that are grown widely and/or receive high applications of pesticides and fertilisers (e.g. potato, wheat, barley and maize). GM traits with significant agronomic potential include late blight resistant potato, Fusarium head blight resistant wheat and Septoria resistant wheat and herbicide- tolerant winter oilseed rape and maize. Following on from these, crops with enhanced nitrogen-use efficiency could provide significant input to the tillage sector in light of EU-based restrictions on nitrogen usage, crops with elevated protein content could offset the costs of imported animal feed and crops with modified oil content/lignocellulose composition could assist in biodiesel/bio- energy production at a regional level. This study is relevant to other European countries that cultivate similar crops and like Ireland, are facing multiple challenges to their tillage sector in the near future. Introduction able agricultural land is devoted to pasture-based systems, with approximately 9% (0.4 m ha) devoted to arable pro- Agriculture is an integral part of the Irish economy gener- duction (Department of Agriculture and Food, 2007a). ating in excess of V8 billion in exports and providing pre- Ireland’s accession to the European Economic Commu- dominantly rural-based employment for over 110 000 nity (EEC) in 1973 precipitated a significant increase in people. Over 3.9 million hectares (m ha) or 91% of avail- crop yields through a greater scientific understanding of Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC 323 Journal compilation ª 2008 Association of Applied Biologists Relevance of GM crops in Ireland M. O’Brien & E. Mullins the processes underlying plant husbandry, chemical in- ensure informed consent, adequate labelling and trace- puts and increased on-farm mechanization (Feehan, ability and to safeguard against the introduction of an 2003). Indeed, between 1985 and 2006 Irish cereal pro- unauthorised GM crop (European Commission, 2008a). duction increased by 4.6%, yet the area under cereals The moratorium was lifted in 2004 to allow GM crops to declined from 0.38 to 0.27 m ha (229%) during the be grown commercially in the EU, but as yet no GM same period (Department of Agriculture and Food, crops are grown in Ireland. 2007a). However, this yield increase came with a signifi- This paperis thesecond in aseries of threefrom research cant social and environmental cost. The number of agri- tasked to examine the possible environmental impacts of cultural workers in Ireland today has declined to cultivating GM crops in Ireland. To be in a position to approximately 40% of what it was in 1973 (Department describe the impact of a range of different GM crops/traits of Agriculture and Food, 2007a), and our environment on Irish biodiversity, it is first necessary to identify those has suffered an enormous deterioration in both water GMcropsthatcouldbesuitedtoIreland’sagri-environment and soil qualities and a very noticeable reduction in bio- over the next 20 years against a backdrop of future agri- logical diversity on farms (Feehan, 2003; reviewed in cultural challengesand alternativemanagementpractices. O’Brien et al., 2008). The goal of this paper is therefore to complete this task and Looking ahead, the changes predicted to occur in agri- provide a level of clarity and focus for future research and culture up to and beyond 2030 will be equally, if not more policy initiatives, be they ecologically or agronomically dramatic, than previous decades. The old challenges of based. Additionally, we highlight the progress being producing cheap and abundant food have been replaced made internationally to genetically modify and/or com- with the more complex issues of peak oil, global warming mercialise maize, oilseed rape, wheat, potato and barley, and potential shortages in global food reserves. There is when applicable to the Irish agri-environment. Our work- now firm consensus among the scientific community for ing assumption on GM crop cultivation is based on the the need to farm in a more sustainable manner. Imple- premise that there is no scientific case for ruling out all mented into European policy the result has seen an GMcrpsdhtroutredigablet- increased awareness among the agricultural sector of the proval: each GM crop should be assessed on a case-by-case necessity to reduce the environmental impact of farming, basis (UK GM Science Review Panel, 2003, 2004). as underpinned through the commitment of farmers (>50 000) to the Rural Environmental Protection Scheme Future macro-challenges faced by the Irish (REPS). tillage industry Yet, as we progress through the technology era, the potential introduction of technologies [e.g. genetically Under theEU’s CommonAgricultural Policy (CAP), Mem- modified (GM) crops] to the management of Irish tillage ber States focussed on elevating crop yields through systems has been championed by some as a positive devel- increased pesticide and fertiliser inputs. It is now accepted opment for crop production in Ireland, but labelled by that such an intensification of agriculture is no longer sus- others as a negative step because of perceived biosafety tainable because of societal concerns for the environment. issues. Genetic modification has been defined as a tech- In addition, multiple challenges to how we farm now exist nique that allows the movement of genes among different at all levels and these must be considered before taking species and also to modify genes so that their expression into account the suitability of specific crops for certain occurs when and how we desire (Beringer, 2000). In agri-environments. 2007, over 114 m ha were cultivated with GM crops across 23 countries worldwide (James, 2007). Yet, Bt Climate change maize is the only commercial GM crop grown within the European Union (EU) on over 110 000 ha across Spain, Climate change will be the single greatest challenge facing France, Portugal, the Czech Republic, Germany and tillage systems into the future. Global temperatures are Slovakia (Kleter et al., 2008). This disparity in GM crop projected to increase by between 1.8▯C and 4.0▯C by the cultivation between European and other Organisation end of the present century because of a doubling of atmo- for Economic Co-operation and Development countries spheric CO 2 (Intergovernmental Panel on Climate has partly arisen because of the de facto moratorium on Change, 2007). By 2040, temperatures in Ireland are the cultivation of GM crops within the EU, which was predicted to increase by 1.25–1.5▯C, with rainfall established in 1998 in response to public concerns amounts expected to increase by up to 15% in the win- regarding the biosafety of GM technology when applied ter months and decrease by up to 20% over the summer to food production. Up to 2003, the response of the EU (Intergovernmental Panel on Climate Change, 2007). At was to introduce a series of legislative measures to a regional level, the principal effects of this change have 324 Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC Journal compilation ª 2008 Association of Applied Biologists M. O’Brien & E. Mullins Relevance of GM crops in Ireland led to more intense rainfall in the northern and western (P)] of Irish rivers and estuaries, with 70% of P (Envi- coasts, with decreases or small increases in the south and ronmental Protection Agency, 2006) and 82% of N east (McElwain & Sweeney, 2007). The viability of (Stapleton et al., 2000) loads attributed to agricultural potato as a commercial crop in these regions will be very sources because of the excessive application (or mis- much dependent on the availability of irrigation water to application) of fertilisers to lands. Rivers in the south- offset drought stress and the degree to which projected east of Ireland have much higher concentrations of rainfall increases in spring and autumn will interfere nitrate than elsewhere because of the greater extent of with sowing and harvesting operations, respectively tillage crops in this region (Environmental Protection (Holden et al., 2003). In contrast, it is predicted that bar- Agency, 2004). It has been estimated that the mean N 21 ley will remain viable with a diminutive change in the loss from land to rivers can be as high as 76 kg ha crops geographical distribution, beyond its present core year21 (for ploughed land) (Neil, 1989). The goal of the in the east and south-east of the country (Holden & Nitrates Directive (Directive 91/676/EEC) is to reduce Brereton, 2003; Holden et al., 2003). The rise in temper- such pollution by increasing the management of nutrient ature and CO 2 levels could possibly extend the growing application on arable (and all farm) systems (European season, thereby increasing the potential for new crops, Commission, 1991); for example, tillage farmers who with forage maize likely to increase in importance in the import organic manures are now limited to 170 kg coming decades (Feehan, 2003; Holden & Brereton, organic N ha21 (Environmental Protection Agency, 2003). Naturally, weeds will adapt to climate change 2006). The EU Dangerous Substances Directive (Directive more rapidly than crops because of their genetic advan- 76/464/EEC) requires control of P and its compounds tage (Bunce & Ziska, 2000) and there will be a tendency (European Commission, 1976), and in Ireland the Phos- for pests and diseases that are currently found further phorus Regulations (Department of the Environment and south in Europe to migrate north towards Ireland’s lati- Local Government, 1998) require local authorities to tude (Holden & Brereton, 2003). implement measures in order to reduce the impact of In the EU25, agriculture accounts for approximately P-induced eutrophication. 9.5% of greenhouse gas (GHG) emissions (Environmen- Independently, legislation governing the application of tal Protection Agency, 2006) and while GHG emissions pesticides is currently being discussed at EU level. The from Irish agriculture have fallen in recent years, agri- revision of Pesticide Directive 91/414/EEC is seeking culture is still the source of a much larger share of GHG a reduction in plant protection products, which could sub- emissions (28%) than in most other developed countries stantially reduce the type of chemical fungicides available because of its importance to the Irish economy (O’Mara to farmers. The ratification of this Directive would seri- et al., 2007). The application of artificial fertilisers under-ously undermine the existing programmes of disease pins present tillage management but the GHG nitrous control for potato, wheat and barley, whose economic oxide (N 2O) is a resulting by-product of this usage and viability is reliant upon fungicide programmes to control has a global warming potential 296 times greater than diseases caused by Phytophthora infestans, Mycosphaerella CO 2Intergovernmental Panel on Climate Change, 2007). graminicola and Rhynchosporium secalis, respectively. Understandably, significant emphasis will be placed on agriculture to share in meeting the EU’s legally binding Common Agriculture Policy target for a reduction of 20% in GHG emissions by 2020 (European Commission, 2008b), which underlines the In 2003, the CAP was reformed to facilitate the decoupling importance of developing novel crops/crop systems to of subsidised income from agricultural production (the reduce the tillage sector’s fertiliser requirements. Luxembourg Agreement) (European Commission, 2008c). This fundamental change to the CAP will be a major driver of agricultural change as the new single farm pay- EU environmental legislation ment, is now linked to environmental, food safety and The EU Water Framework Directive (2000/60/EC) re- animal welfare standards. It is expected that full decou- quires member states to protect, enhance and restore all pling will change the pattern of land use in Ireland, with bodies of surface water to good status by 2015 (European some farmers increasing the intensity of their production Commission, 2000). Presently, 70% of the river channel in order to minimise unit costs, while others may decide length in Ireland would achieve this target, but signifi- that the cost and effort required to work the land is not cant efforts are required to improve the remaining 30% warranted, given the possibility of low or negative returns (Environmental Protection Agency, 2006). Agriculture in the competitive world market. In certain instances, contributes significantly to the eutrophication [i.e. this could result in land abandonment for agricultural enrichment of water by nitrogen (N) and phosphorus production or a gradual withdrawal from farming. Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC 325 Journal compilation ª 2008 Association of Applied Biologists Relevance of GM crops in Ireland M. O’Brien & E. Mullins Intensification of farming practices and land abandon- Challenge of producing sustainable biofuels ment, each has its own potential impact on the environ- ment.Itfollowsthatintensificationislikelyto resultinan Global warming coupled with the imminent arrival of the peak oil scenario has created an urgent need to produce increased use of fertilisers and chemicals for crop man- agement purposes, which will increase the risk of water ecologically friendly fuels. Critically, a biofuel will only contribute to the solution if it is economically, socially quality degradation and biodiversity loss, particularly where it leads to clustering of intensive agricultural and environmentally sustainable (The Royal Society, 2008). While indicative targets of 5.75% for biofuel mar- practices within the country. At the other extreme, land abandonment and the withdrawal of traditional ket penetration by 2010 and 10% by 2020 have been set by the European Commission (Department of Commu- farm management practices may result in the loss of bio- diversity on farmland, as traditional farming contributes nications, Marine and Natural Resources, 2007), the logistics of achieving these outputs in Ireland are signifi- to safeguarding certain existing natural or semi-natural habitats (Environmental Protection Agency, 2006). This cant with up to 250 000 ha of tillage land required to achieve the target of 5.75% alone (Rice, 2007). In the is particularly true for Ireland, where land abandon- ment frequently precipitates afforestation with conifer- short term, ethanol from cereals and biodiesel from rapeseed can contribute to the solution (Department of ous plantations, which are supported through State grants (Feehan, 2003). Communications, Marine and Natural Resources, 2007) but unless large tracts of set-aside pasture is returned to arable cropping, the increased acreage of oilseed rape Mitigating biodiversity loss required for competitive biodiesel production will be in direct competition with land cultivated for food use. Modernagriculturalsystemshaveproducedalandscapein whichmanyfieldshavefewweedsorinvertebrates,which results in decreasing food reserves for birds (Sanvido et al., Conceivable impacts of specific GM traits 2006). The intensification of modern agricultural prac- tice, such as the switch from spring to winter crops, loss As farmers address the need to deliver an economically viable output against a background of higher energy costs of marginal hedgerows and the decline in the area under cultivation have over the past three decades caused a and increased environmental consciousness, a suite of agronomic practices (e.g. intercropping, minimum-till, dramatic decrease in many species that are dependent on traditional arable practices (Curtis et al., 1988; Hickie organic farming and precision agriculture) are available to make arable farming more sustainable. In addition, novel et al., 1999; Taylor & O’Halloran, 2002). Ireland and other governmental signatories to the Convention on plant breeding methods such as marker-assisted selection and genetic modificationarebeing usedtoimproveexisting Biological Diversity have committed to significant reduc- tions of biodiversity loss by 2010 (Convention on Biolog- or generate novel plant traits. But what are the purported benefits to the environment and to tillage farmers – should ical Diversity, 2002), and while most farmers seek to enhance the environmental quality of their farms, they they wish to adopt GM-developed traits? are constrained from doing so by the need to run a prof- itable enterprise (Beringer, 2000). However, efforts have Reducing fungicide and herbicide inputs been made to minimise the environmental impact of till- age agriculture through the promotion of sound envi- The goal of crop protection is not the elimination of pests ronmental practices and/or organic systems with such but to reduce crop losses to an economically acceptable EU initiatives as the REPS. The introduction of crops for level (Sanvido et al., 2006). In 2004, total chemical in- energy production has raised concerns about biodiversity puts for arable crops in Ireland (based on active sub- loss where native ecosystems are converted to meet stances) totalled 1520 tonnes, including 663 tonnes of demand for both food and biofuels. As with all tillage herbicide, 619 tonnes of fungicide, 29 tonnes of insecti- operations, the potential impacts to biodiversity will cide and 209 tonnes of other products (e.g. growth regu- lators and molluscicides) (Department of Agriculture and depend on the crop, its density, duration and distribu- tion on the landscape. Given the range of potential bio- Food, 2007b). Hence, novel crops modified to express energy crops (from tall grasses to trees) impacts to durable disease resistance should present farmers with biodiversity will vary greatly (The Royal Society, 2008) the opportunity to reduce fungicide applications, but using set-aside land to grow biofuel crops will clearly thereby diminishing the quantity of chemical residues have a greater ecological impact relative to intensively in food/feed and in soil and watercourses. From an Irish cropped land (Critchley & Fowbert, 2000; Bracken & context, the significance of such a development cannot Bolger, 2006). be overstated. After herbicides, fungicides are the 326 Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC Journal compilation ª 2008 Association of Applied Biologists M. O’Brien & E. Mullins Relevance of GM crops in Ireland second-most used plant protection product in Ireland weed populations over time (Sanvido et al., 2006; (41% of the weight of active substances) (Department of Owens, 2008). For example, the continuous use of gly- Agriculture and Food, 2007b). The control of fungal dis- phosate in GMHT crops in the USA, Brazil and Argentina eases is a constant challenge for Irish potato and cereal has precipitated the rapid emergence of HT weed bio- growers who rely totally on fungicide applications to types (Powles, 2008), which erodes any initial benefit protect their economic return. The introduction of alter- delivered by the GMHT trait (Sanvido et al., 2006). Cru- native control options would underpin the production of cially, the development of herbicide resistance in weeds improved grain and/or tuber quality, possibly reduce is not a question of genetic modification, as HT weed bi- production costs and in the case of cereals, offset the otypes were prevalent long before the introduction of potential health hazards caused by mycotoxin-producing GM crops (Anon, 2008), and with appropriate manage- Fusarium species. ment control, the control potential of glyphosate systems Herbicides are the most widely used of all plant protec- can be protected (Powles, 2008). tion products in Ireland (44% of the weight of active sub- stances; Department of Agriculture and Food, 2007b). Reducing N and P inputs The main crops currently grown in Ireland that would benefit most from being herbicide tolerant (HT) (based In 2003, 388 000tonnesof N was usedon Irish farms, with either on kilograms of active substances applied per hect- land for arable crops receiving a higher unit application are or/and total hectares grown) include potato, maize, (Coulter et al., 2005), depending on the type of crop winter oilseed rape, wheat and barley and to a lesser ex- (Table 1). Yet, only 30–50% of applied N is assimilated tent oats (Table 1). Potato in particular receives almost by crops with a significant amount of applied N fertiliser a 14-fold higher application of herbicides than all other lost from agricultural fields (Tilman et al., 2002). The crops mainly because of its slow emergence from the modification of plant genotypes to express greater N-use ground and its relatively poor ability to compete with efficiency (NUE) could allow a reduction in N-fertiliser weeds for sunlight. use without a decrease in yield or alternatively, increase Enhanced flexibility in timing of weed control and re- overall yield at existing levels of N usage. Additionally, duced herbicide application frequency are widely claimed crops expressing a NUE trait could present the opportu- reasons to cultivate HT crops (Graef et al., 2007). In addi- nity to expand the possible area of cultivation to include tion, GMHT-associated herbicides (glyphosate and glufo- marginal land. sinate) are less persistent than conventional herbicides, After N, P is considered to be the most important nutri- such as atrazine (Hails, 2002), which is now prohibited ent limiting agricultural production. To reduce P deficien- across the EU (Halford, 2004), and control of certain cies and ensure plant productivity, up to 44 000 tonnes of broad-leaf and grass weeds can be achieved with a single a P-based fertiliser is applied annually to Irish farmland, herbicide (Sanvido et al., 2006). Yet, disquiet remains as with arable crops receiving a higher unit application to whether GMHT crops will benefit crop systems or mit- (Coulter et al., 2005). Balancing farm P inputs and out- igate weed control regimes through the emergence of HT puts (i.e. nutrient management planning) is used to Table 1 Hectares planted and pesticide and fertiliser usage for six common crops grown in Ireland Plant Protection Hectares Total Plant 21 b 21 c Predominant Planted Protection Products Products (active substances, kg h) Fertiliser Usage (kg ha) a b d Crop Use(s) in 2007 (active substances, kg) Herbicide Fungicide Insecticide Others Nitrogen Phosphorus Barley Food & feed 167 500 473 269 1.2 1.2 0.1 0.2 123–167 26–30 Wheat Food & feed 84 300 507 937 1.7 1.9 0.1 1.3 152–203 23–24 Oats Food & feed 21 300 68 006 0.7 1.0 0.1 1.7 113–138 25–26 e e e e e Maize Feed 20 900 39 186 2.5 0.0 <0.1 0.1 NA NA Potato Food 11 700 364 106 13.0 14.1 0.2 0.2 115 102 Oilseed rape Fuel & feed 8200 1478 0.6 0.2 <0.1 0.1 NA NA Feed, feed for livestock consumption; Food, food for human consumption; Fuel, biofuel; NA, not available. aCentral Statistics Office, 2008. b In 2004, unless stated otherwise (Department of Agriculture and Food, 2007b). cBetween 2001–2003 (Coulter et al., 2005). d Growth regulators, seed treatments and molluscicides. eIn 2003 (Department of Agriculture and Food, 2006). Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC 327 Journal compilation ª 2008 Association of Applied Biologists Relevance of GM crops in Ireland M. O’Brien & E. Mullins reduce the quantity of P applied to agricultural land and available for oilseed rape production, which will not to minimise the eutrophication of waterways. Better uti- meet the national targets set by the EU Biofuels Directive lising P bound to the soil without the addition of exter- 2003/30/EC. While modifications to the biology of oilseed nal P inputs is another strategy. It is estimated that up to rape,including decreased podshatter andelevated oilcon- 80% of P fertiliser applied to land is unavailable for plant tent could potentially assist in attaining EU targets, a shift uptake because of adsorption, precipitation or conver- towards second-generation biofuels, produced primarily sion to organic forms. Crops modified with an increased from lignocellulosic biomass, is clearly required and en- level of citrate exudation have a higher capacity to use couraged by the EU (Commission of the European Com- insoluble forms of P, yielding higher biomass when munities, 2006). The Irish climate is better suited to grown in P-limiting conditions (Lopez-Bucio et al., lignocellulosic crops (mainly perennials) such as Mis- 2000). Engineering Irish-specific arable crops with a simi- canthus spp., and it is hoped that the emergence of new lar trait could reduce the use of P fertilisers. Additionally, second-generation biofuel technologies will eventually better utilisation of P in pig and poultry feeds can reduce allow these crops be converted to liquid biofuels (Depart- the quantity of P spread on the land. ment of Communications, Marine and Natural Resources, 2007). In the medium term, lignocellulosic biomass from currently cultivated crops (mainly annual), such as small Reducing CO em2ssions grain cereal-straw, oilseed rape-stalk and maize (whole An associatedenvironmentalbenefitaccruingfrom reduc- plant) could provide alternative sources of bioenergy by their conversion to cellulosic ethanol or use as a solid bio- tions in the previously described crop protectants and/or fertilisers includes a reduction in direct and indirect C2 fuel (Tuck et al., 2006). The various possibilities that genetic engineering can offer to increase bioethanol pro- emissions arising from chemical manufacture, transport and field operations (Advisory Committee on Releases to duction from these crops include modifying biomass properties to reduce processing costs or increase biomass the Environment, 2007). Indeed, the possibility exists for agricultural land to be used to moderate the impacts of yield and reducing agricultural inputs (Torney et al., 2007). Although, cellulose is more difficult and expen- climate change. Specifically, this relates to the cultiva- tion of HT crops in conjunction with minimum tillage to sive to saccharify than starch (Ragauskas et al., 2006), the modification of several crops with plant-produced reduce CO e2issions from soil. Only 4% of arable land in Ireland is established by minimum tillage methods, in hydrolytic enzymes to convert cellulose into glucose shows potential (Sticklen, 2007). Similarly, the reduc- contrast to approximately 30% in the UK (European Conservation Agriculture Federation, 2008). Minimum tion in or modification of lignin structure may reduce the need for a pretreatment process (Ragauskas et al., tillage systems have a much lower fuel demand at 2006; Sticklen, 2007). Increasing crop biomass by approximately 50% of that of the plough-based system genetic engineering is another promising area of (Forristal, 2008). In addition, with reduced soil distur- research. Delaying the onset of flowering has been re- bance, more carbon remains in the soil and therefore ported to increase biomass (Salehi et al., 2005), and less CO 2s released to the atmosphere. Yields of winter improving architectural features such as dwarf stature wheat in Ireland have been shown to be similar for both and erect leaves could potentially increase biomass and min-till systems and plough-based systems (Fortune & yield (Yuan et al., 2008) Murphy, 2003), and thus no loss of productivity is ex- pected. While it is prudent to consider the fact that the introduction of certain HT crops to Ireland could coin- Enhancing the quality of livestock feed cide with a beneficial increase in minimum tillage as Although grass and grass silage is the foundation for most witnessed in North America (Ammann, 2005), it is ruminant production systems in Ireland, it does not con- important to acknowledge that soils in Ireland are dis- tain optimal protein–carbohydrate ratios (McGee, 2000), similar to those in the USA, highlighting the need for regional-specific research on this issue. and therefore the provision of concentrate feed is a criti- cal requirement for both the Irish beef and dairy sectors. The pig and poultry sectors have also a large require- ment for concentrate feed. This feed is currently derived Developing sustainable bioenergy crops from imported GM soybean and GM maize products While localised oilseed rape cultivation in Ireland could (corn gluten feed and distillers dried grain). Sourced potentially meet the biodiesel demand of cooperative- from the USA, Brazil and Argentina over 3.4 million based farmers, because of rotational constraints a theoret- tonnes was imported between 2005 and 2007 to offset ical maximum of approximately 80 000 ha is currently the deficit in domestic feed supplies. The asynchronous 328 Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC Journal compilation ª 2008 Association of Applied Biologists M. O’Brien & E. Mullins Relevance of GM crops in Ireland authorisation of GM cultivars between the EU and GM Improved agronomic/management benefits feed-producing countries has only exacerbated the sharp increase in feed prices experienced in 2007, One of the principal justifications for the development of GM crops is that they reduce production costs and thereby which has continued into 2008 (e.g. 77% increase in soya meal between January 2007 and January 2008 – increase farmer’s margins. Indeed, it is hard to imagine that the rapid uptake of these crops in North America Hughes, 2008). Indeed, it is now apparent that as global land area shifts to non-food production, food and feed would have occurred if farmers did not benefit economi- cally (Sweet et al., 2004). Looking ahead in the short prices will rise. The persistence of this food versus fuel competition will create a significant incentive to devote term, the first suite of GM crops most suited to the Irish agri-environment are likely to be GMHT oilseed rape greater Irish acreage to domestically produced feed of higher protein and energy content. Consequently, as (winter varieties) and GMHT maize. Since their intro- duction into North America, the uptake of both crops land availability becomes an increasing factor, farmers are likely to seek novel crops with elevated protein, has been dramatic (Gianessi, 2008). While issues exist in regard to volunteer control for GMHT oilseed rape sys- energy or enhanced feed digestibility characteristics, thereby reducing Ireland’s dependence on imported tems (D‘Hertefeldt et al., 2008), one of the main benefits cited by farmers who have used GMHT crops to date on feedstocks. One potential benefit of the food versus fuel competition, as Irish oilseed rape acreage is predicted to a commercial basis has been the ‘convenience’ factor (Kalaitzandonakes, 2003). Although often difficult to increase by 440% (3700–20 000 ha) by 2015 (Teagasc, quantify, this category of benefit includes additional 2008), the meal that remains post-crushing will become flexibility in timing of operations (e.g. when to spray an increasingly important source of animal feed protein crops), less time spent crop walking and assessing weed that could displace some imports. Growth in interfarm incidence, savings in use of machinery (e.g. on fuel) and trading of high protein/energy forage and grain crops improved production risk management (i.e. less worry will also help reduce global GHG emissions with lower that failure to treat weeds with herbicides at a critical ‘feed miles’. and narrow time window will result in yield losses) (PG Alternative forages, such as whole-crop barley/wheat Economics, 2003). and maize have increased in popularity because of the reducedlabourandexpertise requiredingrowingandhar- vesting some of these crops and the increased predictabil- Genetically modified traits with the highest ity of their feeding value relative to what is commonly probability of adoption by Irish farmers achieved with grass silage (Mayne & O’Kiely, 2005). Advancement in agriculture biotechnology could further There are no GM crops currently grown in Ireland because improve the nutritional quality and digestibility of whole- the current suite of GM varieties authorised for cultivation crop forages. Technology developed for producing high- in Europe are not suited to the Irish agri-environment. lysine maize as described here could be transferred to Taking into consideration the extensive list of crops that other crops such as wheat and barley to enhance their are being field tested within the EU (Figs 1 and 2), it is levels of important amino acids (Ufaz & Galili, 2008). likely that this scenario will change in the future with Although straw can be fed to ruminants for roughage, Irish farmers being afforded the choice as to whether little nutrition is derived from it. Increasing the ruminant- they wish to grow GM varieties. Although it is not possi- digestible material of straw by 20% would upgrade its ble to predict the level of uptake that may occur, it is nutritional value to that of hay (Gressel & Zilberstein, reasonable to foresee that novel GM crops may be avail- 2003). Furthermore, increasing the bioavailability of P in able to Irish farmers based on the points discussed ear- cereal-based feed by enhancing phytase production may lier. Crops with the greatest potential for genetic reduce the costs for farmers to meet the nutritional modification, from an industry perspective, are those needs of pigs and poultry. Although cereal grains con- under large hectarage and/or requiring high levels of tain P, most is in the form of phytic acid, which non-ru- chemical input, which for Ireland includes barley, wheat, maize and potato. For the likely early adopters, minants such as pigs and poultry cannot digest efficiently. In addition, phytic acid is considered to be an the issues will centre on the potential economic returns, important anti-nutritional factor, preventing the uptake logistics of complying with coexistence regulations and of other important minerals. As phytase supplementa- naturally whether there would be a market for the re- tion is expensive, the most versatile and cost-effective sulting GM commodity. This last point will prove critical, attractive alternative is to deal with the problem at its as markets for animal feed and biofuels are likely to source by developing low-phytate crops (Brinch-Pedersen develop first and could be met through the cultivation of et al., 2002; Raboy, 2007). GM oilseed rape for biodiesel and GM maize for animal Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC 329 Journal compilation ª 2008 Association of Applied Biologists Relevance of GM crops in Ireland M. O’Brien & E. Mullins because maize is unable to compete with weeds during the first month after sowing and mid-to-late season chemical control is hampered by the maize crop canopy. The recent removal from the market of the most effec- tive weed management agent, atrazine, will only hasten the need for an alternative weed control strategy. In the UK’s farm scale evaluations, GMHT maize received one application of herbicide at rates averaging 3.5 L product per hectare, representing a reduction of 57% compared with conventional herbicide use (Champion et al., 2003). Owing to the high level of similarity between farming systems in the UK and Ireland, it is likely that a compara- ble reduction in herbicide use could be achieved in Ireland, therefore providing a prerequisite economic potential to the Irish farmer. The availability of a GM Figure 1 Predominant genetically modified crops that have undergoneze variety with enhanced NUE would also be of benefit considering the increasing costs of fertiliser and field trials in the European Union between 1992 and 2007. The number of field trials is based on the number of applications submitted. It isparatively high demand of maize for N to produce possible that the statistics include rejected applications or applicationsy satisfactory yields (Boehmel et al., 2008). that were later withdrawn. One application can include field triSuch maize varieties are in the early stages of development more than one site and/or that run over the course of several yby the biotech industry. (Source: Joint Research Centre, 2008). Enhancing the protein content and/or the digestibility of forage maize would be of significant benefit to the agri- feed/bioenergy output. In turn this early ‘GM experi- cultural sector in light of Ireland’s dependence on impor- ence’ will afford farmers the opportunity to determine to ted animal feed. Virtually all maize grown in Ireland is what degree they wish to commit to additional GM traits forage maize, that is, the whole-crop above a 0.25-m stub- for the crops listed below. ble is harvested and ensiled. As half of the crop harvested (on a dry matter basis) is in the cob (the remainder in the Genetically modified maize vegetative stover), the non-ripe cobs are an important source of nutrients for ruminants. However, protein con- Up until recently, maize was a marginal crop in Ireland tent in forage maize is low and farmers must supplement with production concentrated in the east, south-east and with urea or soya in order to meet the ruminant’s protein south of the country, where the crop is planted in April– requirement. Maize varieties that produce ripe grain are May and harvested in September–October. Its restricted not available for cultivation in Ireland, so in the short to growing range in Ireland is as a result of its requirement medium term there would be substantial interest among for a soil temperature in excess of 8 ▯C, which has pre- farmers in elevating the protein content of current maize cipitated a trend to sow maize using the plastic mulch varieties. While quality attributes of forage maize have system. This system permits earlier sowing and rapid been neglected by plant breeders (Kingston-Smith & establishment and can increase dry matter yield by Thomas, 2003), recent advancements have demon- 21 approximately 3000 kg ha and ensure consistency in strated the potential to increase the protein content of yield and quality from year to year. A cold tolerant maize, with the lysine content of US varieties of maize 21 21 maize variety, as cited in Zhang et al. (2004), would grain enhanced from 2400 mg L up to 5000 mg L eliminate the costs associated with plastic mulch by (Huang et al., 2006). Indeed, a high-lysine variety permitting earlier planting, which could lead to the (LY038) has recently been approved for commercial use expansion of the crop’s growing range and potentially in the livestock feeding industry in several countries increase national yields. (Ufaz & Galili, 2008). Cell-wall digestibility is also recog- An additional trait that should be considered is the nised as a major target for improving the feeding value inclusion of herbicide tolerance in GM maize varieties. of maize, with varieties having already been developed In 2007, 35.2 m ha of GMHT maize was grown in the with reduced lignin content and higher digestibility world, accounting for 24% of the total area planted (Piquemal et al., 2002; He et al., 2003). (James, 2007). GM maize engineered for tolerance to Although 14% of the US maize crop is used in the pro- herbicides such as glyphosate or glufosinate-ammonium duction of bioethanol from grain starch, there are no would be highly suited to the Irish agri-environment large-scale cellulosic ethanol facilities (>30 m gallons 330 Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC Journal compilation ª 2008 Association of Applied Biologists M. O’Brien & E. Mullins Relevance of GM crops in Ireland Figure 2 Novel traits conferred by genetic engineering in five crops that have undergone field trials in the European Union between 1992 and March 2008. The number of field trials are based on the number of applications submitted (stacked traits were reported separately). It is possible that the statistics include rejected applications or applications that were later withdrawn. One application can include field trials at more than one site and/or that run over the course of several years (Source: Joint Research Centre, 2008). 21 yr ) in commercial production in the USA (Somer- He et al., 2003) and other researchers have demonstrated ville, 2007). To convert the lignocellulose rich stover the concept that maize can be modified into a ‘bio- into bioethanol two strategies can be considered: (a) factory’ for cellulose-degrading enzymes through the modify the characteristics and properties of lignocellu- temperature-inducible expression of the Acidothermus lose so that it can be converted more readily to cellulolyticus endo-1, 4-b-D-glucanase gene post-harvest a desired product in planta or (b) introduce biomass (Biswas et al., 2006). Although genetic engineering pres- conversion enzymes into maize germplasm so the con- ents potential for future biofuel production, it is unlikely version process can be completed more effectively (Tor- that such a GM maize sector could develop without sig- ney et al., 2007). The reduction of lignin content in nificant downstream investment in indigenous refinery maize has been demonstrated (Piquemal et al., 2002; capacity. Ann Appl Biol 154 (2009) 323–340 ª 2008 TEAGASC 331 Journal compilation ª 2008 Association of Applied Biologists Relevance of GM crops in Ireland M. O’Brien & E. Mullins Genetically modified oilseed rape conventional varieties (Good et al., 2007). In a lifecycle assessment of the potential environmental impact of Irishfarmersarewellversedincultivating oilseedrapeand growing GM NUE oilseed rape compared to a conven- although this crop falls short of an ideal environmentally tional variety, savings in energy of up to 22% is pre- friendly alternative to fossil fuels, biotechnology may pro- dicted (Strange et al., 2008). vide some near-term solutions to its drawbacks, at least For Irish farmers, yields of between 3000 and 3500 kg until a better means of producing renewable energy is 21 21 ha for winter rape and 2500 kg ha for spring rape found. Only recently has the potential to increase oil yield been realised using GM technology. For example, in a pre- are required to make the crop economically viable. Yet, even when intensive management practices are adop- liminary study, the overexpression of a yeast glycerol-3- phosphate dehydrogenase (gpd1) in oilseed rape showed ted, oilseed rape is still considered a ‘high’-risk crop as a result of the crop’s sensitivity to competition from a 40% increase in the final lipid conte
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