Exogenous Zinc Forms Counteract NaCl-Induced Damage by Regulating the Antioxidant System, Osmotic Adjustment Substances, and Ions in Canola (Brassica napus L. cv. Pactol) Plants

Abstract

Salinity is the principal natural obstacles for sustainable agriculture, adversely impacting 30% of the world's irrigated land, resulting in food insecurity, particularly in arid and semi-arid areas. Zinc has several functions in plants; nevertheless, the promising roles of nano-zinc oxide particle in plants under salinity stress are not clear. The current study aims to investigate the roles of zinc (water, 75 mg L −1 zinc sulfate (Zn), and 10 mg L −1 zinc oxide nanoparticle (ZNP)) on the mitigation of NaCl stress (6000 mg L −1) on morpho-physiological attributes and yield of canola plants. Salinity exhibited a substantial reduction in canola plant growth, enhanced photosynthetic pigment degradation, and decreased nutrient concentrations. A decrease in the overall yield and a decrease in various individual components were considerably stimulated by zinc application under nonsalinized and salinized conditions. Salinity caused a visible increase in membrane permeability (MP%), malondialdehyde (MDA), and hydrogen peroxide (H 2 O 2) concentrations. Interestingly, zinc application significantly decreased MP%, MDA, and H 2 O 2 concentrations by the upregulation of antioxidant enzymes (superoxide dismutase, catalase, peroxidase) and levels of non-enzymatic antioxidants (ascorbic, carotenoids, and total soluble phenolic compounds). Furthermore, zinc application also enhanced osmoregulation by increasing proline and total soluble carbohydrates accumulation, as well as increased nitrogen, potassium, and phosphorus in the plant tissues in correlation with a decline in sodium and chloride contents. Zinc's, especially ZNP, role in the mitigation the negative effects of salinity on canola growth and yield may be connected with the upregulating oxidative defense system and osmolyte synthesis as well as ionic regulation.

Zinc and Paclobutrazol Mediated Regulation of Growth, Upregulating Antioxidant Aptitude and Plant Productivity of Pea Plants under Salinity

“…A remarkable reduction in chlorophyll under NaCl was recorded in several plants [ 3 , 4 , 5 ]. The decline in chlorophyll under salinity could be attributed to the decrease in chlorophyll biosynthetic or increased enzymatic chlorophyll deprivation [ 30 ], as well as the disintegration of the thylakoid membranes and destruction of chlorophyll by different ROS, and changes in chlorophyll protein complexes [ 4 , 31 ].…”

“…Salt stress influences about 936 Mha of arable lands, causing yearly worldwide monetary losses of 27.5 billion USD [ 1 , 2 ]. Severe salinity induces different physio-biochemical abnormalities, including dual hyperosmotic effects, nutritional imbalance, specific ion toxicity, impaired gas exchange, disturbing water homeostasis, or a mixture of these factors, which reduce plant growth and yield [ 3 , 4 , 5 ]. Additionally, salinity stress manifests an overproduction of reactive oxygen species (ROS), like superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ), which seriously disrupt normal metabolism and causes a drastic physio-biochemical and molecular dysfunction [ 6 , 7 , 8 ].…”

“…Plants under stress conditions activate self-protection strategies to mitigate oxidative injury and disposing of ROS molecules. These include exclusion and compartmentation of toxic ions, as well as overproduction of compatible solutes [ 3 , 7 , 9 ]. Together with nonenzymatic antioxidants (phenolic compounds, carotenoids ”CAR”, flavonoids “FLAV”, ascorbic acid “AsA”, and reduced glutathione “GSH”), plants nullify ROS by upregulating antioxidant enzyme activities that quench O 2 − to H 2 O 2 , and finally into the water and molecular oxygen [ 7 , 10 , 11 ].…”

“…There are different ways to improve salinity tolerance in crops for ensuring food security, involving biotechnological methods and application of some activators [ 13 ]. Accordingly, evaluation of the possible functions of activators like micronutrient and plant growth substances offer an efficient explanation for the enhancement of plant resiliency to the unfavorable impacts of ever-changing ecological disorders [ 3 , 14 , 15 ].…”

“…It has been proposed that Zn supplementation is essential in plants’ protection strategies under salinity. Concerning this, Farouk and Al-Amri [ 3 ] documented that exogenous application of zinc on salt-affected canola plants significantly increased plant growth, photosynthetic pigments, ion concentration, and increased yield.…”