Nonthermal Plasma Regulation of Photosynthetic Performance: Molecular Mechanisms, Chloroplast Responses, and Crop Improvement

ABSTRACT

Nonthermal plasma and plasma‐activated water can improve chlorophyll content and photosynthetic performance, yet the underlying chloroplast mechanisms remain poorly resolved. This review reframes plasma‐induced greening as regulation of photosynthetic competence. We examine how plasma‐derived reactive species influence Ca ²⁺ signaling, MAPK responses, hormone–redox crosstalk, antioxidant priming, chlorophyll metabolism, thylakoid function, and carbon assimilation. We propose a plasma‐response window in which optimized exposure supports PSII protection, photosynthetic performance, and stress acclimation, whereas excessive treatment promotes pigment degradation, lipid peroxidation, photosystem injury, and impaired carbon fixation. Evidence is strongest for PSII preservation, antioxidant activation, delayed senescence, and enhanced whole‐leaf photosynthesis, while direct effects on PSI, ATP synthase, NPQ, Rubisco, tetrapyrrole enzymes, and retrograde signaling remain insufficiently defined.