PENGARUH INTERVAL WAKTU PEMBERIAN DAN KONSENTRASI LARUTAN KRIOPTEKTAN TERHADAP VIABILITAS BENIH DAN PERTUMBUHAN SEMAI JATI PUTIH (Gmelina arborea Roxb.)

White teak (Gmelina arborea Roxb.) is a fast-growing tree species with high economic value and great potential for forest rehabilitation. However, its low seed viability is a major constraint in seedling production. The use of cryoprotectant solutions can protect seed cells and enhance early growth performance. This study was conducted in the screen house of the University of Muhammadiyah Malang from January to March 2025 using a factorial Randomized Complete Block Design (RCBD) with two factors: application intervals (5, 10, 15, and 20 days) and cryoprotectant concentrations (5, 10, 15, and 20 ml/L), each with three replications. The observed parameters included germination rate, vigor index, seedling height and stem diameter, number of leaves, root length and number, as well as fresh and dry weight. The results showed that the application interval significantly affected seedling height and stem diameter, while the interaction between interval and concentration significantly affected all parameters of seed viability and growth. The combination S4K3 (20 days, 15 ml/L) produced the highest germination rate (99.86%), root length (11.63 cm), root number (34.87), and fresh and dry weights (2.98 g and 1.15 g). Treatment S1K4 (5 days, 20 ml/L) yielded the greatest height (10.71 cm), S2K3 (10 days, 15 ml/L) produced the largest stem diameter (1.82 cm), and S1K1 (5 days, 5 ml/L) had the highest leaf number (6 leaves). Overall, longer application intervals combined with moderate to high cryoprotectant concentrations provided the best physiological responses for improving seed viability and seedling growth of white teak