P
RETREATMENT
For some species, a pretreatment following collection of buds, but before surface disinfestation and
excision of anthers, has been found to be beneficial. Yields of tobacco haploids are often increased
by storing excised buds at 7 to 8° C for 12 days prior to anther excision and culture (Sunderland
and Roberts, 1979). For other species, temperatures from 4 to 10° C and durations from 3 days to
3 weeks have been utilized. For any one species, there may be more than one optimum temperature
and length of treatment combination. In general, lower temperatures require shorter durations,
whereas a longer pretreatment time is indicated for temperatures at the upper end of the cold
pretreatment range mentioned above.