Role of metal oxides / nanoparticles in improving growth and antioxidant status under heat stress in wheat (Triticum aestivum L.)
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
The present study was conducted to evaluate the growth, antioxidant potential, free radical
scavenging and membrane stability parameters in root and shoot of two wheat (Triticum
aestivam L.) genotypes (Unnat PBW 343 and HD 296) treated with 1.5ppm and 10 ppm ZnO
and TiO2 nanoparticles (NP) under normal and high temperature (32oC) on the 12th day of
germination. For characterization of ZnO NP, present study employed scanning electron
microscope-energy dispersive X-ray spectroscopy (SEM-EDX) technique and the results
demonstrated different shape and size of NPs such as bunch of irregular particles, round
shaped and small particles. Physiological parameters, viz., shoot and root length, biomass,
germination percentage and biochemical parameters such as activities of antioxidant enzymes,
viz., catalase (CAT), superoxide dismutase (SOD), guaicol peroxidise (GPX) and natural
antioxidants, viz., phenols and flavonols also increased with application of ZnO and TiO2 NPs
in parallel with higher free radical scavenging as measured by 2,2-diphenyl-1-picrylhydrazyl
(DPPH) and ferric reducing antioxidant potential (FRAP). Both ZnO and TiO2 NPs had
promoting effect at lower concentration (1.5 ppm) compared with higher concentration (10
ppm). Though, TiO2NPs improved seedling performance slightly better than ZnO NPs,
antioxidant defence response was higher with ZnO NPs. Nonetheless, compared to the HD
2961 cultivar, the Unnat PBW 343 cultivar had lower malondialdehyde (MDA), hydrogen
peroxide (H2O2) contents and higher upregulation of antioxidative enzymes under heat stress
conditions treated with NP owing to the better expression of antioxidants. Therefore,
pretreatment by ZnO and TiO2NPs at 1.5 ppm, no doubt, improved resistance against heat
stress substantially through increase in GPX and SOD activities, and thereby stabilizing
membrane as evidenced by lower MDA and H2O2 content.