Influence of Pollen Grain Stage at the Time of Hand Pollination as a Factor on Fruit Set of Cherimoya1

Abstract Preliminary research to investigate additional factors to increase results obtained by hand pollination in cherimoya ( Annona cherimola Mill.) revealed that the first flowers to open gave a poorer fruit set with hand pollination than later ones. Flowers that opened earliest had the majority of the pollen grains in the tetrad stage with thick walls, full of starch and did not germinate. Flowers that opened later had a greater proportion of individual pollen grains, no starch grains, and greater cytoplasmic streaming. Many grains germinated after a few hours.