Germination Response of Misopates orontium to Temperature, Light, and Osmotic Stress Under Laboratory Conditions

Abstract

Germination response of Misopates orontium was evaluated under varying temperature, light regimes, and osmotic stress conditions to understand its ecological adaptation and emergence potential in agricultural systems. Laboratory experiments were conducted using controlled incubators to assess seed germination behavior under constant and alternating temperatures, light/dark cycles, and simulated water stress induced by polyethylene glycol solutions. Results indicated that seed germination was highly sensitive to environmental conditions, with maximum germination recorded under alternating temperature regimes and light exposure, indicating a positive photoblastic response and adaptation to surface germination niches. Constant temperatures resulted in reduced germination percentages, suggesting the requirement of thermal fluctuation cues for optimal seed activation. Osmotic stress significantly inhibited germination, with increasing water potential reduction leading to delayed and decreased germination rates, reflecting sensitivity to moisture limitation. Mean germination time increased under both low light and high osmotic stress conditions, indicating slowed metabolic activation. Interaction effects among temperature, light, and osmotic potential were significant, demonstrating that germination is regulated by multiple environmental cues. The species exhibited a flexible germination strategy, enabling synchronization with favorable seasonal conditions in field environments. These traits contribute to its persistence in disturbed agroecosystems and its ability to establish under variable climatic conditions. The study highlights the ecological significance of environmental cues in regulating seed germination and provides insights into the weed’s adaptive strategies. These findings are useful for predicting emergence patterns and developing effective weed management strategies in agricultural systems where M. orontium occurs.