Another major focus of Osborne's research was seed biology. An expert on seed ageing and plant DNA repair, Osborne researched the effects of DNA degradation, repair and telomere length on the viability of seeds. In the 1970s, she was among the earliest to attempt to isolate nucleic acids from ancient seeds, finding that only very short fragments could be isolated from grains from Egyptian tombs. Among her final research projects was a study of the effects on DNA repair in seeds and pollen of exposure to radioactive fallout after the Chernobyl nuclear reactor explosion.