Table 2.

Induced photosynthetic activity and growth attributes by melatonin in various crops under abiotic stresses.

Specie	Stress	Concentration	Functions
Arabidopsis	Heat	1,000 μM	Delayed leaf senescence and maintained growth (Hernández et al., 2015)
Apple	Drought	100 μM	Enhance ABA activity and radical scavenging (Li et al., 2014)
Alfalfa	Drought	10 μmol/L	Increase proline metabolism (Antoniou et al., 2017)
Cucumber	Salinity	100 μM	Overall growth (Wang et al., 2016)
Grapes	Water	200 μmol/L	Improved antioxidative enzymes activity (Meng et al., 2014)
	deficient
Maize	Drought	100 μmol/L	Photosynthesis and growth (Ye et al., 2016)
Perennial ryegrass	High temperature	20 μM	Regulate abscisic acid and cytokinin biosynthesis (Zhang et al., 2017)
Red cabbage	Heavy metal	10 μM	Improved seed germination and reduce the toxic effect of metal in seedling (Posmyk et al., 2008)
Soybean	Multiple stress	100 μM	Boost and maintain the overall plant growth (Wei et al., 2014)
Tomato	Cold and salinity	100 μM	Improved photosynthesis and regulation of photosynthetic electron transport (Zhou et al., 2016; Yang et al., 2018)
Watermelon	Salinity	150 μM	Redox homeostasis and improved photosynthetic activity (Li H. et al., 2017)
Wheat	Drought and metal	500 μM and 1 mM	Increased seedling percentage, growth, and antioxidant enzymes activities (Cui et al., 2017; Zuo et al., 2017)