Key points are not available for this paper at this time.
Panax ginseng is a shade-adapted perennial crop that exhibits high sensitivity to heat stress. Despite its agricultural importance, the physiological mechanisms linking prolonged heat stress to growth inhibition remain poorly understood. In particular, how early physiological changes translate into cumulative growth impairment remain poorly understood. This study analyzed the temperature-dependent physiological responses of 1-year-old P. ginseng by integrating phenotypic observations, vegetation index–based assessments, and photosynthesis analyses under various temperature regimes. Time-course measurements were employed to capture the progressive physiological deterioration resulting from sustained heat exposure. Elevated temperature significantly inhibited both shoot and root growth, inducing progressive physiological decline in 1-year-old P. ginseng. While vegetation indices declined under high-temperature conditions, gas-exchange analyses revealed a stepwise progression of photosynthetic limitation. This process was characterized by early-stage stomatal regulation, followed by more severe impairment of photosynthetic capacity during prolonged heat exposure. Notably, these physiological responses became substantially more pronounced as temperatures surpassed the critical threshold of 30 °C. Our findings demonstrate that prolonged high temperature drives a coordinated shift in photosynthetic limitation, ultimately leading to growth inhibition in P. ginseng. This study establishes a physiological framework linking vegetation indices with heat-induced photosynthetic regulation, providing a basis for the early assessment of heat stress severity in ginseng cultivation.
Kim et al. (Wed,) studied this question.