Table 2.

Effects of exogenous melatonin application on photosynthetic apparatus under salt stress.

Stress	Crop	Effects on Photosynthesis	Reference
Salinity	Wheat	High water status, low level of H2O2 content, and balanced [K+]/[Na+] ratio in leaves, high content of proline, protein, soluble sugars essential amino acids and Ca2+ in leaves resulting in a high photosynthetic rate.	[86]
	Sugarbeet	Increases the level of photosynthetic net rate, chlorophyll fluorescence, and chlorophyll content.	[81]
	Cotton	Reduction of ROS production, increases plant biomass and chlorophylls level, preservation of mitochondria and grana lamella of chloroplasts.	[84]
	Rice	Upregulation of gene expression associated with antioxidant system, photosynthetic parameters, and ROS scavenging enzymes. Reduction of electrolyte leakage.	[83]
	Tomato	Reduction of chlorophyll degradation; alleviated PSII inhibition and OEC damage.	[78]
	Oats	Upregulation of genes encoding ROS scavenging enzymes, stress-responsive, NAC transcription factors, and PSII core proteins. Increases stomatal conductance and chlorophyll content. Reduced the levels of MDA and electrolyte leakage.	[13]
	Cucumber	Improvement of photosynthetic efficiency, inhibition of chlorophyll degradation, reduction of MDA and ROS contents. Increased the expression of antioxidant-associated genes.	[77]