The study looked at how much pollen apple flowers release and how this changes over time. Some apple varieties like Alice, Discovery, and Lobo produce a lot of pollen, while others like Quinte, Julyred, and Summerred release less. For Discovery, the peak pollen release happened 3-5 days after the flower opened. Even after all the petals fell off, apple flowers can still release pollen, but the pollen may not be as good for fertilization after ten days.