Himani Singh

Green synthesis of nano zinc oxide and evaluation of its impact on germination and metabolic activity of Solanum lycopersicum.

In the present study, zinc oxide nanoparticles (ZnO NPs) were rapidly synthesized at room temperature by treating zinc acetate dihydrate with the flower extract of Elaeagnus angustifolia (Russian olive). The formation of ZnO NPs was primarily confirmed by UV-visible absorption spectrum in the range of 250-700nm. XRD analysis and DLS particle size analyzer revealed the size of ZnO NPs. The FTIR spectrum revealed the presence of phytochemicals in the flower extract mediated ZnO NPs. Moreover, the morphology of the ZnO NPs was determined using SEM. Seeds of Solanum lycopersicum (tomato) were separately treated with different concentrations of synthesized ZnO NPs and zinc sulphate (ZnSO4) salt suspensions (common zinc supplement). The effect of these treatments on seed germination, seedling vigor, chlorophyll, protein and sugar contents as well as on the activities of lipid peroxidation and antioxidant enzyme were studied. Leaves of plants treated with 6.1mM concentration of ZnO NPs recorded maximum reflectance while it was minimum in plants treated with 1.2mM concentration of NPs. The effect of synthesized ZnO NPs on seedling vigor, pigment, protein and sugar content was found affirmative at lower concentrations contrary to control and ZnSO4 salt. The inhibitory effect at higher concentration of NPs indicated importance in the precise application of NPs, in Zn deficient system, where plant response varies with concentration. To the best of our knowledge this is the first report on Elaeagnus angustifolia mediated synthesis of ZnO NPs and their effects on germination and physiological activity of tomato.

Physiological and biochemical effects of salicylic acid on Pisum sativum exposed to isoproturon

ABSTRACT In the present study, attenuation of isoproturon (IPU) toxicity by salicylic acid (SA) was observed. Seven-day-old seedlings of pea (Pisum sativum L. cv. Azad P-1) were treated with 10 mM IPU. IPU influenced physiological and biochemical parameters. IPU significantly inhibited growth variables like shoot and root height, fresh and dry biomass of the pea. The contents of carotenoids, chlorophylls, protein and activity of nitrate reductase were inhibited significantly. IPU enhanced the accumulation of H2O2, ion leakage and lipid peroxidation due to induction of oxidative stress in pea. The activities of antioxidant enzymes, namely superoxide dismutase, catalase and ascorbate peroxidase increased while the activities of guaiacol peroxidase decreased. However, exogenous SA regulated the toxic effects of IPU. The indices of oxidative stress appeared to be alleviated by SA. Pigment content and activities of enzymes increased approximately up to the level of control. IPU caused non-target phytotoxicity to P. sativum. The natural growth regulator/allelochemical has potential to overcome the adverse effects caused by IPU. Abbreviations: CAT: catalase; EL: electrolyte leakage; IPU: isoproturon; LP: lipid peroxidation; MDA: malondialdehyde; NR: nitrate reductase; POD: guaiacol peroxidase; SOD: superoxide dismutase; TCA: trichloroacetic acid

Physiological and biochemical roles of nitric oxide against toxicity produced by glyphosate herbicide in Pisum sativum

The present study assessed the response of pea plants exposed to herbicide induced oxidative stress in the plants present in agriculture field. We analysed the effect of exogenous nitric oxide (NO) regulated chlorophyll and protein content, nitrate reductase enzyme activity and antioxidant enzyme activity in herbicidetreated green pea (Pisum sativum L.). Glyphosate (0.25 mM) treatment alone or in combination with 250 μM sodium nitroprusside (SNP, 250 μM with glyphosate) was given to pea and we observed the changes in biophysical and biochemical parameters. During oxidative stress ion leakage is the first step of cellular damage. Supplementation of SNP with glyphosate significantly reduced ion leakage and moderately reduced H2O2 and malondialdehyde (MDA) content. SNP also increased chlorophyll content and antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (POD) activity as compared to herbicide treatment alone. The present result suggests that NO protects pea plants from damage caused by glyphosate.

Salicylic Acid Induced Changes on Some Physiological Parameters Symptomatic for Oxidative Stress in Maize (Zea mays L.) Grown under Cinnamic Acid Stress

In the present work, alleviation of cinnamic acid (CA) stress by salicylic acid (SA) was observed. CA influenced the physiological and biochemical parameters. CA significantly repressed growth variables like shoot and root height, fresh and dry biomass of the maize seedlings. The contents of chlorophylls, carotenoids, protein and activity of nitrate reductase were inhibited significantly. CA enhanced the accumulation of proline, ion leakage and lipid peroxidation due to induction of oxidative stress in maize. The activities of antioxidant enzymes, namely superoxide dismutase, catalase and ascorbate peroxidase, guaiacol peroxidase increased in CA stress. However, exogenous SA regulated the toxic effects of CA. The indices of oxidative stress appeared to be attenuated by SA. Pigment content and activities of enzymes increased approximately up to the level of control. CA caused phytotoxicity to Zea mays. The natural growth regulator has potential to overcome the adverse effects caused by CA.

Alleviation of Deleterious Effects due to 2-Benzoxazolinone by Exogenous Application of Spermidine in Solanum lycopersicum

ABSTRACT Chemicals in root exudates can have deleterious effects on tomato (Solanum lycopersicum L.) growth and yield. Spermidine (Spd) acts as a plant growth regulator that plays a role in the regulation of physiological processes during stress. The present study reports the effect of exogenous Spd to mitigate the allelopathic stress of 2-benzoxazolinone (BOA) on tomato. The BOA treatment reduced fresh weight (FW) and dry weight (DW), relative water content (RWC), and decreased chlorophyll a, b, and carotenoid contents. Total soluble sugar (TSS) and protein contents were decreased due to treatment with BOA. Proline content, lipid peroxidation (LP), and antioxidant enzyme activities increased in BOA-treated plants. Electrolyte leakage (EL) from plant leaves increased due to treatment with BOA. Exogenous application to foliage with Spd increased RWC, FW and DW, photosynthetic pigments, and antioxidant enzyme activity in the BOA-treated seedlings. Protein and sugar contents, LP, and EL were reduced in seedlings exposed only to BOA. Exogenous foliar application of Spd appeared to induce protection against allelochemical stress by strengthening the protective system and helped maintain physiological functions in plants.

Exogenous Application of Salicylic Acid to Alleviate Glyphosate Stress in Solanum lycopersicum

ABSTARACT Pesticides have nontarget toxicity and affect growth and yield of Tomato (Solanum lycopersicum L.). Salicylic acid (SA) acts a as plant growth regulator that supports plant defense systems. Activity of SA was studied to determine whether it reduced glyphosate toxicity and benefited growth and yield of tomato plants. Glyphosate at 0.25 mM and SA at 1 mM were applied to tomato seedlings at 20 days after sowing. Glyphosate decreased shoot and root length and fresh and dry weight of seedlings. Carotenoids, chlorophylls, and protein contents and activity of nitrate reductase were inhibited. Accumulation of sugar, proline content, and oxidative indices (H2O2, ion leakage, lipid peroxidation) was enhanced due to treatment with glyphosate. The antioxidant enzymes superoxide dismutase and guaiacol peroxidase increased; activities of catalase and ascorbate peroxidase decreased. Anthocyanin content declined and phenyl ammonia lyase enzyme activity increased. Pigment content and activities of antioxidant enzymes increased up to the level of the control. The level of glyphosate used caused phytotoxicity to tomato. Salicylic acid has the potential to overcome adverse effects caused by glyphosate if application is done before exposure.