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Can GM and non-GM crops coexist? Setting a precedent in Boulder County, Colorado, USA
Abstract
The coexistence of genetically modified (GM) and non-GM crops has emerged as one of the key issues in the ongoing debate over genetically engineered food. Some growers of organic and conventional crops fear economic losses if GM components are present in their fields or harvested products. We describe a public process in Boulder County, Colorado, USA, in which protocols were developed to encourage coexistence of GM and non-GM maize (Zea mays L.) on publicly owned Open Space farmland. The protocols (1) approve GM maize hybrids on a case-by-case basis; (2) promote communication among neighboring farmers; (3) provide for a 46 m buffer zone to keep cross-pollination between adjacent fields below 1%; (4) support measures to minimize the probability of insect resistance development; and (5) call for monitoring and dispute resolution mechanisms. These protocols, which will go into effect in the 2003 growing season, were developed with the intention of supporting organic, conventional, and GM crop farmers and encouraging shared responsibility for identity preservation of non-GM crops.
... The main focus of these studies was to gather information about adequate separation distances to ensure coexistence and about the dependence of crosspollination on the distance within maize fields. Several studies have been performed to evaluate the impact of pollen drift from fields containing GM corn to neighboring non-GM cornfields (Byrne and Fromherz, 2003;Devos et al., 2005;Weber et al., 2007;Njontie Tchiengue, 2010;Viorica et al., 2017). The accidental gene flow is more pronounced under the conditions of peasant agriculture, where crop plots are close together and sometimes several varieties are grown in the same plot. ...
In Cameroon, maize is the most widely cultivated cereal and is consumed by more than one third of the population. This study aimed to evaluate in the tropical conditions the cross-pollination rate in four recipient synthetic maize varieties by xenia phenomenon depending on distance to the pollen source and wind direction. The experimental design was triplicated split plot with each replication arranged as a 576 m2 Latin square area. The combined analysis of variance showed a highly significant effect (p<0.001) of the gap from pollen source and wind direction on the cross-pollination rate of the recipient varieties. CMS 8704 yellow-grain variety which is the pollen donor and the white grain receiver cultivars CMS 2019, CMS 8501, CMS 9015 and Shaba had one to seven days’ difference between the female flowering of the recipient variety and the start of male flowering of the donor. These synthetic varieties differed significantly for the number of leaves per plant, the 100-seeds weight, the plant height, and total kernels weight per plant, with cultivar Shaba showed the highest values. The highest cross-pollination rates were found in the first maize rows facing the donor field and the genetic pollution decreased with increasing distance from the donor source. At the same distance from source, the pollution level higher the North. The implementation of appropriate separation distance (>10 m) is recommended for reducing genetic pollution and ensuring coexistence of different genotypes in maize production field.
... The most developed coexistence system practice has developed in the USA, where GMO cultivation is permitted. Not only broad buffer zones used, but also safety protocols may contribute to individual approval of each GMO type, and provide monitoring mechanisms and procedures to resolve disagreements between neighbouring farms (Byrne & Fromherz, 2003). ...
... Ecological Indicators 114 (2020) 106317 Table 2 Hierarchical indicator tree of risk of non-compliance for organic crop production. (Chen et al., 2013;Tian et al., 2015) Quality of irrigation water The highest single factor index of irrigation water (Ai et al., 2018) Quality of atmosphere environment The highest single factor index of atmosphere environment (Pandey and Pandey 2009a,b) External environment Width of buffer zone Width of buffer zone of the organic production base (m) (Byrne and Fromherz 2003;Damgaard and Kjellsson 2005;Hanson et al. 2007;Damgaard andKjellsson 2005, Hanson et al., 2007;Bloem et al., 2017) Distance from pollution sources Distance between organic production base and pollution sources (km) ...
Farming management and certification are essential for organic agriculture development to make sure that farming practices are compliant with organic regulations. To improve the efficiency of organic certification and farm management, a risk-based indicator system of organic crop production was established according to literature review and Chinese organic regulations. Three dimensions, 11 themes, and 25 indicators were selected and the weights of which were determined through Analytic Hierarchy Process. The highest weight was assigned to the production dimension (0.59), followed by management (0.24) and environment (0.17). The three highest risk themes in the sequence were plant protection, detection and soil fertility management with a weight of 0.17, 0.15 and 0.12, respectively. At the indicator level, pesticide detection rate, nutrient satisfaction rate, the proportion of non-chemical treatment, the severity of crop diseases, pests and weeds, and the quality of soil environment ranked top five according to the weight of their risk. Chemicals application including pesticides and fertilizers was the main concern in organic production and certification. The results will provide producers, inspectors, and certifiers useful references to reduce the risk of non-compliance, and increase the integrity and credibility during organic production and certification.
... In the structured refuge system, cross-pollination of ears on the first row next to the PS refuge plants resulted in an average of 5.4% purple kernels, but decreased significantly across the remaining rows. Several studies have found relatively high levels of cross-pollinated kernels in the first row (0.8 m from Bt corn) of non-Bt corn planted adjacent to Bt corn, with levels ranging from 3 to 82% (Byrne and Fromherz 2003;Ma et al. 2004;Bannert et al. 2008). Lowest levels of cross-pollination (1.3% overall mean) were observed in the fourth row, a 75% drop at 2.5 m from the nearest purple-seeded plants. ...
Gene flow between Bt and non-Bt plants can have implications for resistance management. In 2013 and 2014, field trials in Maryland and Louisiana measured gene flow in three refuge systems: (1) structured refuge stand of purple-seeded corn flanked on both sides by stands of yellow corn; (2) seed blend of yellow corn containing purple corn as refuges; and (3) seed blend of purple-seeded corn containing yellow corn as refuges. The presence of cross-pollinated purple kernels was used as a marker to quantify gene flow. In the structured refuge, cross-pollination between Bt and structured refuge plants averaged 5.4% on adjacent rows and decreased significantly moving away from the interface. For refuge system 2, outcrossing of pollen from the refuge plants was < 1% in ears of neighboring Bt plants both within and on adjacent rows. Cross-pollination was generally higher for plants nearest to the refuge plant. In refuge system 3, outcrossing of pollen from neighboring Bt plants caused 18.6% refuge kernels expressing the purple trait. Laboratory bioassay showed that consumption of a meridic diet containing 6% refuge kernel tissue collected from a 95:5% seed blend field caused significant larval growth inhibition of the corn earworm, Helicoverpa zea (Boddie). Overall findings suggest that effects of gene outcrossing from refuge plants to Bt plants in the seed blend systems are likely not a great issue, but significant gene flow from neighboring Bt plants to refuge plants could reduce the number of homozygous susceptible larvae produced and favor survival of heterozygotes.
Abiotic stress such as high temperature at flowering is one of many conditions reducing yield of corn (Zea mays L.). Mixing corn cultivars with diverse functional traits increases within-crop diversity and provides a potential means of mitigating yield losses under stress conditions. We conducted a three-year field study to investigate the effects of cultivar mixtures on kernel setting rate, pollen sources, and yield. This study consisted of six treatments, including two high temperature-tolerant (HTT) monocrops of WK702 and DH701, two high temperature-sensitive (HTS) monocrops of DH605 and DH662, and two HTT–HTS mixtures of WK702-DH605 and DH701-DH662. The anthesis–silking interval (ASI) was 0.9–1.6 days shorter in mixtures than in monocrops. Kernel setting rate was increased in mixtures (86.4%–88.7%) compared with those in monocrops (74.7%–84.1%) as a result of synchrony and complementarity of pollination. Grain yields of the HTT–HTS mixtures increased by 13.3%–18.7%, equivalent to 1169 to 1605 kg ha⁻¹, in comparison with HTS corn monocrops. The results of SSR markers showed that cross-fertilization percentage in corn cultivar mixtures ranged from 29.3% to 47.8%, partially explaining yield improvement. Land equivalent ratio (LER) was 1.12 for corn mixtures and the partial land equivalent ratio (e.g., > 0.5) showed the complementary benefits in corn mixtures. The results indicated that mixing corn cultivars with diverse flowering and drought-tolerance traits increased yields via pollination synchrony.
On the coexistence of genetically modified (GM) and non‐GM maize, the isolation distance plays an important role in controlling the transgenic flow. In this study, maize gene flow model was used to quantify the MTD0.1% and MTD1% in the main maize planting regions of China, those were the maximum threshold distance for the gene‐flow frequency equal to or lower than 1% and 0.1%. The model showed that the extreme MTD1% and MTD0.1% were 187m and 548m, respectively. The regions of northern China and the coastal plain, including Hainan crop winter‐season multiplication base, showed a significant high risk for maize gene flow, while the west south of China was a largest low‐risk areas. Except for a few sites, the isolation distance of 500m could yield a seed purity of better than 0.1% and meet the production needs of breeder seeds. The parameters of genetic competitiveness (cp) were introduced to assess the effects of hybrid compatibility between the donor and recipient. The results showed that hybrid incompatibility could minimize the risk. When cp=0.05, MTD1% and MTD0.1% could be greatly reduced within 19 m and 75 m. These data were helpful to provide scientific data to set the isolation distance between GM and non‐GM maize and select the right place to produce the hybrid maize seeds.
Undesired pollen-mediated gene flow (PMGF) in large-scale agriculture has received considerable attention for their ability to affect biological invasions. However, it has been not yet sufficiently understood how landscape structure and large-scale anthropogenic dispersal influence the gene spreading process. To explore the possible gene flow from crop species to wild relatives, we performed a literature review in ecosystem PMGF research for four major transgenic crops (maize, rice, wheat, oilseed rape). We found that whether pollen flow results induce a high cross-pollination rate mainly depends on the types of genetically modified (GM) species and cropping practice. Interestingly, the increase in the plot size of a pollen donor can lead to the increase in PMGF under ideal field conditions. However, while in a much larger landscape, it rapidly drops due to the exponential decrease in pollen density and the relatively low out-crossing rates. In large-scale field surveys, seeds of those plants with dormancy capability amplify the occurrence of transgene invasion and can remain alive in the seedbank for several years. Furthermore, in comparison with the distance-based methods, more and more spatio-temporal simulation models have proposed that a higher up-scaling percentage of GM crops is acceptable in a coexistence area of GM and non-GM crops. This highlights that the fate of (trans)genes should be emphasized in designing coexistence approaches. These results carry implications for gene dispersal management and indicate areas for future work, such as how to incorporate the response functions of different pollination factors into simulating models.
This work is the first study of adoption of GM crops by French farmers. The GM crop technology case was a fertile field for the study of technology adoption but existing literature mainly focuses on studies of these issues in USA, Africa and Asia. In France, main production area of maize in Europe, the agricultural sector is very atypical compared to the agricultural sector investigated in the existing literature on the GMO adoption. By a study of the GM crop adoption in the French context and within the main production area, the south-west region of France, this study reveals 4 determinant factors that shape the choice of GM or NGM maize cropping. Some of the factors pointed by this study are in line with the existing literature on technology adoption and output uncertainty and input uncertainty (uncertainty on the expected marginal benefits and costs to sustain the new technology). Other factors identified under the atypical French agriculture sector distinctive features are particularly novel. These new factors are linked to the implementation of the UE regulation on GM/NGM coexistence in the context of small fragmented farms (need of coordination between farmers to prevent GM dispersal) and importance of the market outlets proximity to federate farmers. These novel results pinpoint that in the French context there is a need of both vertical coordination (farmers with the operators downstream the supply chain as the outlet industrial) and horizontal coordination (among farmers in neighbourhood situation) to foster the technology adoption in such industry context.
Wir haben im Rahmen der Wirkungspfadanalyse (Kap. 3) festgestellt, dass die Untersuchung von Wirkungen und Risiken von GVO skalenspezifisch unterschiedlich intensiv erfolgten. Für große Skalen liegen zunehmend weniger wissenschaftlich abgesicherte Kenntnisse über potenzielle Auswirkungen vor. Hier ergab sich die Möglichkeit, die Methodik der ökologischen Modellierung in einem neuen Zusammenhang anzuwenden und in diesem Anwendungsfeld innovativ zu erproben. Wir beschreiben hier zunächst die Modellkonzeption und die Parametrisierung und sodann die ersten Anwendungsergebnisse für verschiedene Raumausschnitte (Kap. 5).
In modern agricultural politics, organic farming and genetic engineering occupy opposite ends of the spectrum. In the Ronald-Adamchak household, the world is not so black and white. Ronald is a professor of plant genetics at the University of California, Davis. Adamchak manages the student-run organic farm. Together, they're exploring the juncture where their methods can meet to ensure ecologically friendly farming. This book roughly chronicles one year in their lives. Through dialogue with friends and family, the authors thoughtfully explore the use of GE crops. The authors discuss the contents of their own pantry, what they choose to feed their children, and criteria for the use of GE in agriculture. From their personal vantage points, Ronald and Adamchak explain what geneticists and organic farmers actually do, and help readers distinguish between fact and fiction in the debate about GE crops. Each section of the book addresses a different issue related to the role of GE and organic farming in food production. Ronald provides a farmer's view of the philosophy and practice of organic farming and how it differs from conventional agriculture; Adamchak describes the tools and processes of genetic engineering, the potential ecological benefit of using GE technology to generate plants, and the associated risks. At the end of the book, they describe one of their typical family dinners, explain their choice to bring both genetically engineered and organic food to their table, and share some of their family's best recipes.
Pollen is an important vector of gene flow in maize (Zea mays L.). Experiments were conducted to investigate the duration of pollen viability and the effectiveness of isolation distance for controlling gene flow. Pollen longevity was tested by collecting pollen at dehiscence and exposing it in a thin layer in the open air and sunshine for prescribed time periods before assessing pollen viability by measuring seed set after pollination and scoring visual appearance. Isolation distance efficacy was evaluated by growing 12.8-m2 plot of maize at various distances from a 4000-m2 pollen source. The pollinator contained either a genetic leaf or seed marker that allowed pollen flow to be measured. Pollen maintained viability for 1 to 2 h after dehiscence depending on atmospheric water potential. The theoretical, maximum distance viable pollen could move was 32 km, assuming pollen was transported linearly at the maximum average afternoon windspeeds for our location, viability was maintained for 2 h, and pollen settling rate was ignored. Cross pollinations occurred at a maximum distance of 200 m from the source planting, and only a limited number of cross pollinations occurred at the shortest distance (100 m). No cross pollinations occurred at 300 m from the source planting. The results are consistent with conclusions that maize pollen is desiccation intolerant and has a high settling rate. The results indicate isolation distance can be a useful tool for controlling gene flow via pollination in research scale plantings.
The atmospheric dispersion and subsequent deposition of corn (Zea mays L.) pollen emitted from plants in two 18-m diameter plots were studied in 39 tests at Brookhaven National Laboratory to compare the spread of this large pollen to that of smaller pollens studied previously. Concentrations were measured by wind-impaction samplers mounted at four heights (0.5 to 4.6 m) and at five distances from the source on 20-degree radii. Deposition was measured by greased microscope slides on the ground.
Data were analyzed in terms of current meteorological dispersion theory. Normalized centerline concentrations, crosswind integrated concentrations, plume widths and heights, and mass flux are presented as functions of distance and compared to similar data from ragweed (Ambrosia) and timothy (Phleum pratense) sources of comparable size. Normalized centerline and crosswind integrated deposition and velocity of deposition are also presented as functions of distance and are compared to ragweed and timothy pollen data. The study shows that corn pollen is not transported as far by the wind as smaller pollens, does not disperse as widely in either the horizontal or the vertical direction and settles to earth more quickly, much of it within the source itself.
The dispersion of corn pollen is influenced by its large size and rapid settling rate. At 60 m from the source in the downwind direction, concentrations average about 1% of those at 1 m. Width of the pollen plume at 60 m is less than that of smaller pollens under similar conditions. The rate of settling opposes the rate of upward dispersion so that the height of the pollen plume does not increase continuously with downwind distance. At 60 m from the source concentrations integrated in the crosswind direction average from 3 to 6% of those at 1 m. The total amount of pollen remaining airborne at 60 m is 5% of that at 1 m.
Total deposition within the source plot is greater than that outside. Deposition per unit area at 60 m downwind is only 0.2% of that near the source. Crosswind integrated deposition at 60 m varies from 0.5 to 0.8% of that at 1 m. The velocity of deposition at 32 m from the source averages about 33 cm/sec.
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Agricultural biotechnologies are anchored to a scientific paradigm rooted in experimental biology, whereas sustainable agriculture rests on a biological paradigm that is best described as ecological. Both biotechnology and sustainable agriculture are associated with particular social science paradigms: biotechnology has its foundation in neoclassical economics, but sustainability is framed by an emerging community-centered, problem-solving perspective. Fundamentally, biotechnology and neoclassical economics are reductionist in nature. Sustainability and community problem-solving, however, are nonreductionist. Given these differences, we might see the development of two rather distinct systems of food production in the near future.
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