Pretreatment of Flower Buds - Exposure of excised flower buds to a low temperature for some time, e.g., at 3-5°C for 2 days or at 7-8°C for 12 days for tobacco, prior to removal of anthers for culture may markedly enhal1ce the recovery of haploid plants . In some species, however, a brief exposure of anthers to a high temperature is reported to have a promotory effect, e.g., at 35°C for 24 h in Brassica campestris. It contrast, the best pretreatment for cereals like wheat, rice, barley, etc. seems to be 3-28 days at 4-10°C; this increases the frequency of green plants. The pretreatment temperature and duration may be considerably affected by plant species, genotype and stage of anther development.