Table 1.

Role of different antioxidant assays in salt-tolerance mechanism of Zizyphus.

Traits	Impacts	References
ROS	Its normal production is effective for normal functioning of plants. Its over-generation within cell compartments is indicative of stress conditions which are toxic for plants’ health.	[33]
MDA	Production of MDA content is indicative of stressed plants.	[34]
	Its reduction is effective for a decrease in lipid peroxidation of membranes that occurs due to an excess of salts.	[35]
	Higher salt-tolerance mechanism recorded through reduction in lipid peroxidation under salt stress.	[36]
H2O2	The production of H2O2 within plant cells and compartments is indicative of stress conditions faced by plants. Its scavenging is made possible by CAT activity naturally.	[37]
SOD	It is important to disturb the O2 to form H2O2 and remove the harmfulness of the superoxide anion.	[38]
POD	POD level is enhanced in Z. spina-christi under high salinity levels which contributes to scavenging of toxic ROS.	[38]
CAT	It mainly contributes to the reduction of H2O2 which is manufactured in light respiration in Zizyphus species.	[38]
APX	It also reduces the H2O2 generation in Zizyphus fruit species against osmotic stress conditions.	[39]
Glutathione	It is involved in maintaining normal cellular redox system of fruit plants either in normal or even in stressed conditions.	[40]
	H2O2 and its derivatives are quickly reduced through glutathione.	[41]
	It has excellent scavenging potential against salt stress.	[42]
Proline	Proline is considered an antioxidant that improves salt tolerance in Zizyphus plants.	[5]
	Proline may act as a signaling molecule in order to maintain osmotic regulation.	[43]
	Proline synthesis is largely increased in leaves and roots.	[43]
GB	It is very well known to regulate photosynthetic pigments and protein stability. Regulation of oxidative injury is necessary for higher yields. Gola cultivars of Z. rotundifolia are salt-tolerant and accumulate more glycine betaine than proline.	[44]
Photosynthetic pigments	Regulation of photosynthetic machinery is necessary for higher yields.	[45]
	Photosynthetic pigments rupture due to an excess of salts	[46]

ROS = reactive oxygen species; MDA = malondialdehyde; H₂O₂ = hydrogen peroxide; SOD = superoxidase dismutase; POD = peroxidase; CAT = catalases; APX = ascorbates and GB = glycine betaine.