Effects of donor genotype and bud sampling on microspore culture of Brassica napus

The effects of genotype, intravarietal donor plants, planting density, inflorescence age, bud position, and bud developmental stage on embryo production in Brassica napus L. were investigated. Embryo yields, frequency of normal embryo production, and direct plantlet regeneration were genotype dependent. Embryo yield ranged from 4 to 196 embryos/anther equivalent, normal cotyledonous embryos varied from 6 to 72% of total embryos produced, and direct plantlet regeneration from embryos occurred from 1 to 47% of embryos subcultured. The G231 line was superior in all three factors Embryo production also was affected by the physiological condition of individual donor plants. Dense plantings reduced plant and bud size, leading to reduced microspore production. In some genotypes embryo production was affected negatively at dense planting densities (3 plants/pot), while in others the rate was unchanged, the plants maintaining high embryogenic potential. The highest frequency of embryogenesis was obtained from cult...