Verification of a Lagrangian pollen dispersion model and sensitivity to particle size and environmental conditions

Abstract

<p>There is controversy in using genetically modified crops. And there are two sides to this controversy. One side wants to grow 100% genetically modified corn. The other side wants to grow organic crops. The development of a Lagrangian pollen dispersion model will help determine the amount of outcross in open pollinated crops. By inputting the wind direction, wind speed, atmospheric stability and the location of cornfields the model can be used to predict the percentage of outcross in the field. Once the pollen dispersion model is completed, corn growers can use it to find the percentage of outcross in their field. This model can also be used for field setup; it can help determine the distance from adjacent cornfields the grower should plant. The model can also be used to predict the amount of outcross in a field. This study found that the Lagrangian Pollen Dispersion Model was able to predict the direction and concentration of maize pollen. The concentration values did not match with the observations exactly, but in general the model predicted pollen dispersion where the observations showed pollen concentration. Pollen dispersion is sensitive to pollen grain size. Larger pollen grains land closer to the source field because of the larger terminal fall speed associated with the pollen grains and the opposite for smaller pollen grains. A pollen size distribution in the model matches with observations the best. This shows that a pollen size distribution should be used when accounting for pollen terminal fall speed. Sensitivity tests on wind speed and atmospheric stability showed that stronger wind speeds caused the pollen grains to land farther from the source field than lighter wind speeds and that stronger instability also caused pollen grains to land farther from the source field than under neutral or weak instability conditions. With wind speeds greater to 2 m s−1, increasing atmospheric instability did not change the distribution of the pollen grains. With wind speeds less than 2 m s−1, increasing atmospheric instability caused the pollen grains to travel farther from the source field.</p>