Abstract

The Hang Kra Rog Phu Phan cannabis variety, is a landrace variety of Thailand. It is a short-day plant in which light is a crucial factor in both the vegetative and reproductive growth phase. The aimed of this study was to investigate the photoperiod-sensitive stage and morphology of flowers of Hang Kra Rog Phu Phan cannabis variety. The experiment was conducted using a completely randomized design (CRD) with 20 treatments and three replicates in an indoor cultivation system. Plants were subjected to a controlled long photoperiod of 18 hours per day in a vegetative growth room, followed by a transfer to a reproductive growth room with a photoperiod of 12 hours per day, which took place every 2 days. Data on the flowering stage and morphological characteristics of inflorescences were recorded in the first, second, third and fourth weeks after flowering. The result of the experiment showed that the Hang Kra Rog Phu Phan cannabis variety takes an average of 23 days from the onset of receiving short-day light (12 hours per day) until the appearance of the first stigma. There is a period during which cannabis responds to the light, lasting approximately 14 days from the start of receiving short-day light until the stage of inflorescences panicle initiation and 9 days from inflorescences formation until stigma appears.