Chromosome-Pairing and Pollen Viability in Desmodium ovalifolium Wall × Desmodium heterocarpon (L) DC. Hybrids

Abstract

Lack of genetic compatibility can result in low viable seed production in wide crosses. One year of an ongoing hybridisation program, during which 1333 Desmodium ovalifolium × Desmodium heterocarpon crosses were made, resulted in only two F₁ plants. An examination of four stages of microsporogenesis (metaphase I, first division segregation, late tetrad microspore production, and pollen shed) was conducted for two lines of D. ovalifolium, three lines of D. heterocarpon and five D. ovalifolium × D. heterocarpon F₁ hybrids made over a 2- year period. Both parental lines and hybrids had low levels of metaphase I univalents, anaphase I laggards, abnormal tetrad microspore production, and had high percentages of pollen stainability. Lack of chromosome homology does not appear to be the reason for low hybrid production in controlled crosses between D. ovalifolium and D. heterocarpon.