Rapid generation scheme in asparagus (Asparagus officinalis L.) breeding: Flowering response and pollen germination in the second cycle flower induction with carbamate treatment

Flower induction treatment with a carbamate compound was studied for constructing the rapid generation scheme in asparagus breeding. Viable seeds were obtained by the crosses with carbamate-induced male flowers, and the hybridity and diploidy of the offspring were confirmed by isozyme and flow cytometric analyses. Flowering response and in vitro pollen germination of the plants of the second generation induced with the carbamate treatment were also investigated. Germination rates of the first and second generation seeds induced with carbamate treatments were a little different in 'Geynlim' and similar in 'Mary Washington 500W'. Percentage of flowered seedlings was, however, higher in the second cycle treatment than in the first one in both cultivars. Although great variation in pollen germination was found even with or without carbamate treatments in each population, there was no distinct difference in average percentage of pollen germination among the populations. These results suggest that flower induction with the carbamate compound can be applied to the rapid generation scheme in asparagus breeding, e.g., to produce homogenic cultivars including both sexes in a short term for genetic and systematical breeding purposes.