In vitro pollen grain germination and starch content in species with different reproductive cycle. II. Malus domestica Borkh. cultivars Sarkrimson and Golden Delicious

Malus domestica Borkh., which has a short flowering period, presents mature pollen grains with or without starch. During in vitro germination starch is always synthesized before tube emergence and hydrolised when tube growth has come to its end. The differences in the two cultivars’ behaviour between the two considered years are explained on the basis of environmental factors.