Thermal Stress-Induced Alterations in Cell Membrane Permeability of Two Wild Datura Species from the Menal Forest Region, Rajasthan

Cell membrane permeability is a key physiological indicator of thermal stress in plants. The present investigation was conducted to evaluate the effect of hyperthermia on the membrane stability of two wild Datura species-Datura innoxia Mill. and Datura metel L. var. fastuosa (L.)-collected from the Menal Forest region of Rajasthan. Leaf samples were exposed to temperature regimes of 40?C and 45?C for 1, 2, and 4 hours. The extent of membrane injury was assessed through the quantification of soluble sugar and protein leachates expressed as a percentage of untreated controls. Results revealed that both species exhibited increased solute leakage with higher temperature and exposure duration, signifying progressive damage to membrane integrity. Datura innoxia showed moderate leakage (sugar: 21.5?82.7%; protein: 19.4?76.2%), whereas Datura metel var. fastuosa displayed comparatively higher leakage (sugar: 23.8?86.4%; protein: 21.5?82.1%). These findings indicate that Datura innoxia possesses relatively greater thermo-tolerance than D. metel var. fastuosa (L.). The study highlights differential heat resilience among congeners, which may contribute to understanding stress physiology in wild Solanaceae taxa of semi-arid environments.