2.3. Pollen collecting and cross-pollination analyzing
Pollen collecting was manipulated for three sunny days duringthe flowering period, September 5–7, 2013. Ten transgenic maizeplants per direction at the full-bloom stage were randomly chosento mark their pollen using brilliant blue staining. The marking timewas at 6:30–8:00 a.m. every day. After 12:00 a.m., pollen grainswere tallied on five sticky traps (glass slides, 0.10 × 0.10 m) coatedwith Tween20 at every location from 1 m to 500 m lied in eightdirectional transects . Sticky traps were fixed on maize stems1.2 m above the earth to match the height of flowering maize. Stickytraps were replaced every day. Meteorological data, including windspeed and direction, air temperature, precipitation, atmosphericpressure, and moisture were recorded in a micro meteorologicalstation in the field. Pollen was counted using a haemocytometerand a light microscope under 10× magnification.