POLLEN VIABILITY AND POLLEN TUBE ATTRITION IN CRANBERRY (VACCINIUM MACROCARPON AITON)

The content of mature seed in a cranberry fruit increases with stigmatic pollen load.
On average, however, only two seeds result for every tetrad of pollen deposited.
What then is the fate of the two remaining pollen grains fused in each tetrad? Germination in vitro revealed that most of the grains in every tetrad were viable and could initiate a pollen tube (90% of tetrads generated 3-4 pollen tubes). Using a semi-vivo technique, excised styles of receptive pistils were implanted in agar, dosed with two, four or many pollen tetrads, and incubated for two days.
On average, the counts of pollen tubes exiting the cut style bases averaged one quarter the counts of tetrads applied to stigmas; doubling the pollen load doubled the counts of tubes, with heaped pollen loads yielding >20 pollen tubes.
Gametophytic selection via pollen tube attrition in the style appears to explain the discrepancy between stigmatic pollen load and the count of mature seeds in a cranberry fruit.

IX International Vaccinium Symposium

J.H. Cane

pollination, fruit set, seed set, pollen load, germination, Ericaceae

https://doi.org/10.17660/ActaHortic.2009.810.74