To our knowledge, little attention has been paid to evaluating ZnO nanoparticles (ZNPs) roles in plants grown under salinity stress. In this study, seeds of lupine (Lupinus termis) plants were grown in plastic pots and exposed to 0 (control) and 150 (S) mM NaCl with or without priming with different concentrations of ZnO [20 mg L−1 (ZNPs1), 40 mg L−1 (ZNPs2), and 60 mg L−1 (ZNPs3)] for 20 days. Salinized plants showed a reduction in plant growth parameters (root length, shoot length, fresh weight, and dry weight) and in the contents of photosynthetic pigments (chlorophyll a and b, and carotenoids) and Zn, as well as in the activity of catalase (CAT) against control plants. On the other side, salinity stress boosted the contents of organic solutes (soluble sugar, soluble protein, total free amino acids, and proline), total phenols, malondialdehyde (MDA), ascorbic acid and Na, as well as the activities of superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) in stressed plants over control plants. However, seed-priming with ZNPs mostly stimulated growth of stressed plants, which was accompanied by reinforcement in the levels of photosynthetic pigments, organic solutes, total phenols, ascorbic acid and Zn, as well as in the activities of SOD, CAT, POD, and APX enzymes over stressed plants alone. On the contrary, priming with ZNPs caused a decrement in the contents of MDA and Na in stressed plants relative to salinized plants alone. It is worthy to mention that, this improvement in salt tolerance of plants primed with ZNPs was more obvious in plants primed with ZNPs3 and grown both in unstressed and stressed regimes. Thus, our findings suggest that seed-priming with ZNPs, especially 60 mg L−1 ZnO is an effective strategy that can be used to enhance salt tolerance of lupine plants.

The Possible Roles of Priming with ZnO Nanoparticles in Mitigation of Salinity Stress in Lupine ( Lupinus termis ) Plants

Influence of Pseudomonas aeruginosa as PGPR on oxidative stress tolerance in wheat under Zn stress.

Zinc, zinc nanoparticles and plants.

Zinc-induced oxidative damage, antioxidant enzyme response and proline metabolism in roots and leaves of wheat plants

The objective of the present study was to investigate the effects of cadmium-zinc (Cd-Zn) interactions on their uptake, oxidative damage of cell macromolecules (lipids, proteins, DNA) and activities of antioxidative enzymes in tobacco seedlings as well as roots and leaves of adult plants. Seedlings and plants were exposed to Cd (10 µM and 15 µM) and Zn (25 µM and 50 µM) as well as their combinations (10 µM or 15 µM Cd with either 25 µM or 50 µM Zn). Measurement of metal accumulation exhibited that Zn had mostly positive effect on Cd uptake in roots and seedlings, while Cd had antagonistic effect on Zn uptake in leaves and roots. According to examined oxidative stress parameters, in seedlings and roots individual Cd treatments induced oxidative damage, which was less prominent in combined treatments, indicating that the presence of Zn alleviates oxidative stress. However, DNA damage found in seedlings, and lower glutathione reductase (GR) and superoxide dismutase (SOD) activity recorded in both seedlings and roots, after individual Zn treatments, indicate that Zn accumulation could impose toxic effects. In leaves, oxidative stress was found after exposure to Cd either alone or in combination with Zn, thus implying that in this tissue Zn did not have alleviating effects. In conclusion, results obtained in different tobacco tissues suggest tissue-dependent Cd-Zn interactions, which resulted in activation of different mechanisms involved in the protection against metal stress.

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The Effects of Cadmium-Zinc Interactions on Biochemical Responses in Tobacco Seedlings and Adult Plants

The impact of foliar boron sprays on reproductive biology and seed quality of black gram.

Zinc deficiency is not only the cause of low productivity of crops, but it also results in low zinc content in seeds, which leads to poor dietary zinc intake. To study the effect of zinc foliar application on improving plant yield and seed zinc content for human consumption, chickpea plants were raised in refined sand culture with deficient (0.2 µM) and sufficient (1µM) supply of zinc under glass-house conditions. Prior to initiation of the reproductive phase, zinc was applied as 0.1% ZnSO4 foliar spray to both zinc sufficient and deficient plants. The plants exposed to different zinc treatments were studied for pollen and stigma structure and their involvement in fertilization and seed yield. Zinc deficiency induces flower abortion, pollen, and ovule infertility leading to low seed set and ultimately its yield. Foliar application of ZnSO4 to zinc deficient plants at the time of initiation of flowering partially reverses the adverse effect of zinc deficiency on pollen-stigma morphology, pollen fertility, and greatly enhanced seed yield of plants. Zinc foliar application improved not only the boldness and vigor of seeds in zinc-deficient plants, but also the seed zinc content in zinc-deficient seeds as well as the sufficient ones.

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Improving reproductive efficiency of chickpea by foliar application of zinc

Significant changes were observed in the antioxidant systems in the leaves of black gram (Vigna mungo L., var. DPU-88-31) grown under deficient and excess supply of Zn. Plant grown with Zn supply ranging from 0.01 to 10.0 μM under glasshouse conditions showed optimal growth and biomass yield at 1.0 μM Zn supply. Deficient (0.001 and 0.01 μM) as well as excess (2.0 and 10.0 μM) supply of Zn decreased the concentrations of chlorophyll, carotenoids, and nonprotein thiols and increased that of ascorbate. The activity of superoxide dismutase and carbonic anhydrase was decreased at deficient levels and increased with increase in Zn supply up to 10 μM. At both stages of growth, the activities of antioxidant enzymes, such as catalase and ascorbate peroxidase, were decreased, whereas the activities of glutathione reductase and peroxidase were increased at both deficient and excess supply of Zn. An accumulation of hydrogen peroxide and thiobarbituric acid-reactive substances was observed in Zn-stressed leaves, indicating oxidative damage. Different responses to deficient and excess supply of Zn were observed in the production of oxidative damage.

Induction of oxidative stress and antioxidant responses in Vigna mungo by zinc stress

Enhanced yield and nutritional enrichment of seeds of Pisum sativum L. through foliar application of zinc

Black gram plants subjected to varying levels of Zn supply (0.01 to 10 microM Zn) showed optimum growth and dry matter yield in plants receiving 1 microM Zn. The dry matter yield of plants decreased in plants receiving 0.01 and 0.1 microM Zn (deficient) and excess levels of Zn (2 and 10 microM Zn). The plants grown with Zn deficient supply showed delayed flowering, premature bud abscission, reduced size of anthers, pollen producing capacity, pollen viability and stigma receptivity resulting in poor pod formation and seed yield. Providing Zn as a foliar spray at pre-flowering stage minimized the severity of Zn deficiency on reproductive structure development and enhanced the seed nutritional status by enhancing seed Zn density, seed carbohydrate (sugar and starch content) and storage proteins (albumins, globulins, glutenins, and prolamines).

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Bhavana Gupta

Papers

The impact of foliar boron sprays on reproductive biology and seed quality of black gram.

Improving reproductive efficiency of chickpea by foliar application of zinc

Induction of oxidative stress and antioxidant responses in Vigna mungo by zinc stress

Enhanced yield and nutritional enrichment of seeds of Pisum sativum L. through foliar application of zinc

Foliar application of Zn at flowering stage improves plant's performance, yield and yield attributes of black gram.