The Relationship between Embryo and Endosperm in Interspecific Hybrids in PennisetumL. Rich

In the interspecific cross [diploid Pennisetum typhoides X hexaploid (P. typhoides X P. purpureum)] X diploid P. typhoides, embryos and endosperms in the same ovule may respond differently to treatment with the growth substance gibberellic acid, as may do different genotypes. Size of embryo and size of its endosperm are positively correlated in some genotypes but not in others. Large fully developed normal embryos may be associated with normal, retarded, degenerate or even no endosperm at all. Conversely, large normal endosperms, even in mature seeds, may contain large, small, or no embryos. Fully developed embryos may be viable regardless of whether they had been associated with normal, retarded or degenerate endosperm, or even no endosperm at all. It is concluded that the embryo is not always dependent on the endosperm during its early development and that a degenerating endosperm need not have a detrimental effect on the development of its embryo or on the viability of the latter.