(d) (h) ①) () Figure 2 Embryo and endosperm development of hybrid Guang-lu-ai4/O.alta at 1,3 and 7 DAP.(a)1 DAP small globular-shaped embryo (arrow)and normal free endosperm nuclei;(b)1 DAP.small globular-shaped embryo(arrow)and degenerating free endosperm nuclei:(c)1 DAP,fertilization trace (arrow)and fertilized egg cell:(d)3 DAP.normal pear-shaped embryo (arrow)and endosperm cells:(e)3 DAP.embryo developmental stagnation (arrow) and degenerated free endosperm nuclei:(f)3 DAP.egg cell fertilization stagnation.showing fertilization trace(arrow)and unfertilized polar nuclei left (arrow head)in single-fertilized embryo sac:(g)7 DAP.globular-shaped embryo with incompact structure(arrow)and degenerated free endosperm nuclei: (h)7 DAP.embryo differentiating organs(arrow)and cellular endosperms;(i)degenerated egg apparatus and tissues in chaos in unfertilized embryo sac at 1 DAP:(j)female-germ unit degeneration(arrow)and tissues in chaos in unfertilized embryo sac at 3 DAP:(k)7 DAP.degenerated egg apparatus(ar- row)and polar nuclei (arrow head)in unfertilized embryo sac:(1)7 DAP,degenerated female-germ unit (arrow)and nucellus tissues occupation in the distorted锦8ya品 reproduction Biology of plant reproduction 17