Effect of Reduced Water Potential on Imbibition Curve and the Triphasic Pattern of Seeds in Solanaceae Species

Seed imbibition and germination under water stress conditions are critical determinants of successful crop establishment; therefore, understanding imbibition responses under osmotic stress is essential for improving seed quality assessment and management strategies for crop production under suboptimal water availability. This study aimed to analyze the effect of reduced water potential on the imbibition curve and triphasic pattern of seeds in several Solanaceae species. The study used seeds from three Solanaceae crops—chili (Capsicum annuum L., varieties Simpatik and Sempurna), tomato (Solanum lycopersicum L., varieties Niki and Rempai), and eggplant (Solanum melongena L., varieties Tangguh and Provita). The seeds were subjected to various levels of osmotic stress using polyethylene glycol (PEG 6000) to simulate water potentials of 0.00, −0.30, −1.90, and −4.10 MPa. Lower water potential in the growing medium reduced the seed’s ability to absorb the water. The triphasic pattern consistently appeared only in chili seeds, whereas in tomatoes and eggplants, it varied across varieties and water potential conditions. Lower water potential delayed the end of Phase I and prolonged the duration of Phase II. These findings confirm that the standard imbibition pattern cannot be generalized to all seeds, and therefore, the imbibition response is specific to seed type, variety, and germination environment.