Rising temperatures due to global warming increase evaporation and reduce soil water availability, inhibiting the growth of rubber seedlings (Hevea brasiliensis), especially roots. This study aims to analyze the growth characteristics of rubber seedlings of PB 260 and GT 1 clones, test the effect of water deficit due to watering frequency on the growth of PB 260 clones, and assess the impact on GT 1 clones. The method used a Separate Plots Design in a factorial Randomized Group Design with two factors: clone (PB 260 and GT 1) and watering frequency (once every 1, 3, 5, and 7 days), repeated three times. The research was conducted in the experimental field of Faculty of Agriculture, Islamic University of North Sumatra, Medan. The results showed the best root growth in watering every 3 days (PB 260) and every 5 days (GT 1). Daily watering causes water saturation, inhibiting root growth. The study contributes to early selection of drought-tolerant clones in nurseries.
plant physiology; water stress; seedling adaptation