Abstract
To assess the environmental effects of genetically modified (GM) crops and to gather data to support regulations to control the co-existence of GM and non-GM crops, we studied the percentage of maize hybrids over a range of several hundred meters. In a large experimental field, we recorded the number of airborne pollen grains, the percentage of hybrids, and various meteorological factors over 3 years. Here we focus on the spatial variation in long-range hybrid percentages and the effects of weather. (1) The total rainfall from the date of first anthesis of the donor plant until the day prior to the pollen emission peak affected the number of airborne pollen grains during the peak period of pollen emission. Rainfall also had a major effect on the variation in number of airborne pollen grains with passage of day. (2) The percentage of hybrids in the recipient field decreased exponentially with distance from the donor field, but did not reach zero even at 800m from the donor field. It continued to decrease slightly, and did not become a constant even at the furthest side of the recipient field. (3) Correlations between the percentage of hybrids and meteorological factors were greater at mid range (50-200m) than at long range (200-800m). (4) The higher the wind speed, the smaller the decreasing rate in hybrid percentages in the area of the recipient field with distance from the donor field. (5) The stronger the solar radiation, the larger the decreasing rate in hybrid percentages in the area of the recipient field with distance from the donor field. Further studies are planned to model pollen emission and hybridization processes.
