• Water relations dominate early plant physiology as a unifying theme, integrating transpiration, water uptake, and wilting dynamics under varying environmental conditions to explain plant hydration strategies [3], [4], [19].

• Growth regulation by plant hormones is a central organizing mechanism linking morphology, development, and reaction to environmental cues, evidenced by auxin studies and growth hormone work [5], [10], [11].

• Photobiology and photosynthesis are framed as interconnected light-driven processes, with attempts to separate reactions and characterize photochemical steps [17], [18].

• Electrochemical and ionic balance in plant tissues is a core thread, tying cell sap composition, electrolyte uptake, protein charge, and metal distribution into a unified view of plant ion homeostasis [1], [7], [9], [12], [15].

• Environmental and stress physiology scrutinizes how day length, temperature, frost, and drought shape growth, reproduction, and resilience in plants [6], [13], [14].