(2)In vivo Induction A. Biological Methods a) Pollination with distantly related species b) Delayed pollination ) Semigamy半配生殖 egg and pollen nucleus do not fuse to produce a zygote d) Twin seedling:双生苗( Natural parthenogenesis单性 HEJE n/n, n/2n, n/3n; where n is a parthenogenic seed e)Chromosome degradation B Physical methods C. Chemical methodsA. Biological Methods a) Pollination with distantly related species b) Delayed pollination c) Semigamy 半配生殖 Egg and pollen nucleus do not fuse to produce a zygote d) Twin seedling: 双生苗( Natural parthenogenesis 单性 生殖 n/n, n/2n, n/3n; where n is a parthenogenic seed e) Chromosome degradation B. Physical Methods C. Chemical Methods (2) In vivo Induction