Floral biology and reproductive phenology of golden apple (Spondias dulcis Frost.) in subtropical terrace soil condition

Knowledge of reproductive biology is the prerequisite for crop improvement through hybridization. So, floral morphology, anthesis, and pollen viability of golden apple were studied to manifest the reproductive biology for utilization as breeding tools. Observations revealed that this deciduous fruit tree gave birth to bright pink panicles accompanying new leaves at apetalous shoot tips during the onset of spring (February), blooming continued for 26 days from the 28th day of panicle initiation (PI), and fruit setting completed within 64 days of PI. Over a three-week-extended flowering cycle, flower opening rose exponentially from 2.0 flowers/panicle on the starting day to a peak of 656 flowers/panicle on day eight, and then decreased gradually to a stop on the 20th day. The racemose type inflorescences had creamy-white hermaphrodite flowers each taking five sepals, five petals, ten anthers and five styles with prominent pinkish ovary. Exhibiting nocturnal anthesis nature, over 91% floral buds bloomed between 6 to 10 pm at night, whereas 6 am to 4 pm daytime period had no blooms. Notably, pollen viability was above 80% till four hours of anthesis (83.34%), then declined drastically to 3.60% in ten hours. Out of 3855 floral buds/panicle, 3577 were bloomed of which 10.34% turned into fruits and 3.13% matured. Floral buds that were protected from outcrossing didn’t set fruits denoting non-synchronous gametic maturity. Therefore, for golden apple improvement, crossing should be performed at night within four hours of anthesis during the second week of blooming in the spring season.