Post-shedding dehydration and in vivo temporal germination of Crocus pollen

Pollen hydrodynamics during exposure and dispersal, and in vivo temporal germination were examined in five species of Crocus. Pollen is panto-aperturate, with a variable number of pores or colpi-like apertures. At dispersal pollen contains 49 – 52% water in spring and autumnal flowering species, and 36 – 38% water in winter flowering species. After exposure at 18 – 21‡C and relative humidity (RH) 40 – 55%, pollen of each species dehydrates exponentially to reduce the water content to 6 – 7%, with specific harmomegathic changes according to the aperture type. Germination occurs close to the pollenpapilla interface on the stigma, and both dry and hydrated pollen show similar germination curves. Germination is however, temporally delayed by 30 – 40 minutes in dehydrated pollen, compared with hydrated pollen.