Enhanced Diurnal Crassulacean Acid Metabolism (CAM) Activity in Kalanchoe pinnata (Lam.) Pers. under Drought Stress: Physiological Plasticity and Climate Adaptation Potential in Ghana

Abstract

Kalanchoe pinnata, commonly known in Ghana as Africa Never Die, is a succulent species with significant ethomedicinal and ecological value. This study evaluated its CAM photosynthetic plasticity under drought stress using leaf tissue pH as a proxy for nocturnal acid accumulation. Ten replicate plants per treatment were grown in pots and subjected to well-watered (control) or drought-stress conditions. Experimental tracking was initiated at the University of Energy and Natural Resources (UENR) campus vegetation structures. Leaf samples were collected at 04:00 h and 16:00 h. Tissue pH was significantly lower at night than during the day in both treatments (paired t-tests, p < 0.001). Drought-stressed plants showed significantly stronger nocturnal acidification (3.38 ± 0.03 vs 4.17 ± 0.05 in controls; t(18) = 14.01 , p < 0.001 ) and a larger diurnal pH amplitude (ΔpH = 2.97 ± 0.07 vs. 1.90 ± 0.05 ); t(18) = -12.77 , p < 0.001 ). These results demonstrate enhanced CAM activity under water deficit, highlighting the species’ adaptive capacity in the face of climate variability in tropical West Africa. The findings support the potential use of K. pinnata in restoration and climate-resilient agroforestry systems.