Floral morphology of tuberose (Agave amica (Medik.) Thiede & Govaerts)) provides critical insights into compatibility and seed setting

The existence of dichogamy and self-incompatibility are notable challenges that pose hindrances in inter and intraspecific crosses, essential for achieving successful seed production in tuberose. Information on the mechanisms of incompatibility and breeding of tuberose is lacking. In this context, the present study was conducted with 14 diverse tuberose varieties which were screened for morphological, floral biology, self and cross-incompatibility and seed setting behaviour. The result revealed that all varieties showed significant variations. Phule Rajani and Arka Nirantara possessed 4 carpels, 7–9 tepals, and a tetralocular ovary, emphasizing the unique floral characteristics of tuberose. In most of the genotypes, anther dehiscence started simultaneously with anthesis (between 9.15 AM and 10.30 AM) except Srinagar, Phule Rajni, Arka Nirantra, Arka Vaibhav, and Arka Suvasini. Duration of stigma receptivity was 48 h in all the genotypes except Arka Nirantra and Arka Suvasini where receptivity was up to 72 h. All the 14 varieties were found to be totally self incompatable under controll selfing conditions. The results of artificial cross-pollination show that the genotype Arka Prajwal exhibited cross-compatibility only when used as a pollen parent whereas, the varieties Rajat Rekha, Hyderabad Double, Calcutta Double, and Swarna Rekha were observed as complete cross-incompatible. Phule Rajni, Hyderabad Single, and Arka Nirantara are the best seed and pollen parents regarding pollen viability, germination, and seed-setting. Further, these findings suggest further research focusing on pollination processes, pollen-pistil interactions, fertilization mechanisms, zygote development, and potential degeneration of both embryo sacs and zygotes coupled with cytological investigations that would significantly enhance the understanding of compatibility factors for selecting suitable parents for future cross-breeding programs in tuberose genetic improvement.