Enhanced Seed Development in the Progeny from the Interspecific Backcross (Fagopyrum esculentum × F. homotropicum) × F. esculentum

To facilitate the introgression of F. esculentum into the traits of F. homotropicum, several accessions of the hybrids between these two species were pollinated with F. esculentum as the recurrent parent. The embryo in vitro rescue was performed to increase the recovery of backcross progenies. The F₂ generation was more amenable than F₁ hybrids to produce backcross progenies. The F₁ hybrids were backcrossed twice with common buckwheat (pin-type F. esculentum) (recurrent backcrossing). Also, alternate backcrosses with common buckwheat and F. homotropicum (congruity backcrossing) were carried out. Pollen tube growth of BCF₁ × F. esculentum (thrum) and F. homotropicum × BCF₁ was the disturbed penetration exceeded for all initial interspecific hybrids, and its requirement was proportionally lower when the common buckwheat was used as the recurrent parent and as the last parent of congruity hybrids. Effects of both common buckwheat and F. homotropicum on seed success rate for hybridization were observed. Growth of hybrid embryos before rescue, regeneration of mature hybrids all increased recurrent and congruity backcrosses and inter-crosses between F₁ plants and selected fertile plants of the second congruity backcrosses.