Variation of Phenology of Flacourtia rukam in Two Different Habitats and Their Relation to Rainfall, Dry Days, and the Plant Water Status

The phenological shift of rukam (Flacourtia rukam [Zoll & Moritzi]) describes plant health. This local edible fruit is becoming increasingly rare. Trees of F. rukam were found in Pasuruan Regency, East Java, including the Purwodadi Botanic Garden (PBG), a conserved plant, and Sekarmojo Village as cultivated plants. This study aimed to analyze the spatial variation in the phenology of two Rukam populations and its relationship with rainfall intensity (RQ), dry days (DD), and plant water status. This study was conducted from 2020 to 2022 using secondary data from the BMKG, such as daily rainfall and the number of days without rain. Phenology and relative water content (RWC) were directly observed every week in two trees at each location. Phenological activities at the two locations were analyzed using the Mann-Whitney test, while the relationships among climate change, RWC, and phenology were analyzed using SEM WarpPLS. The research showed a spatial variation in phenology shown by fallen leaves, flower buds, and young and ripe fruits. Increased RWC was significantly influenced by increased RQ and decreased DD. Therefore, RWC was a mediator variable in influencing phenology, shown by a positive influence on young leaves, flower bloom, and fruit set, and a negative influence on fallen leaves and flower buds. RQ, DD, and RWC directly influenced the phenology of leaves, flowers, or fruits.