A very significant improvement of the total yield of androgenetic green plants after anther culture is presented. The process involves treatment of the donor plants by spraying at different stages around the meiosis with a chemical hybridization agent (CHA) solution, fenridazon-potassium. When harvested at the normal uninucleate pollen grain stage, anthers have shown during in vitro culture very significant increases in embryo production. Compared to the control, we observed up to a 20-fold increase in the production. Moreover, when cultivated later, anthers still remained embryogenic. Therefore the process appears to be very efficient and to allow a broadening of the target period for androgenesis in vitro. The regeneration was not disturbed by the CHA treatment and, as shown in this paper, the technique seems to be applicable to a large range of genotypes. Cytological observations revealed both a low frequency of aneuploidy among the regenerated plants and peculiar features in the pollen grain walls after treatments; a triploid plant was observed. Hypotheses to explain the phenomenon are presented and related to previous observations on the effects of gametocide substances like ethrel, male sterility and pollen dimorphism on androgenesis.