(2) Characteristics of Haploids a) fertility Fully male and female sterile b) heredity Expression of recessive genes Homozygous and stable after chrom ' doubling Doubled haploid, DH)（2）Characteristics of Haploids a) Fertility Fully male and female sterile b) Heredity Expression of recessive genes Homozygous and stable after chrom’ doubling (Doubled haploid, DH)