Nanotechnology in Plant Growth Promotion and Protection. Группа авторов

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21.3 Lupine 20, 40, and 60 mg/L Seed priming (12 hours) under salt stress (150 mM NaCl) + + + Latef et al. (2017) 20 Onion 10 and 20 mg/L Seed treatment in petri‐plate for 10 days + + + Raskar and Laware (2014) 30 and 40 mg/L Seed treatment in petri‐plate for 10 days − − − 25 Peanut 400 and 1000 mg/L Seed treatment (3 hours) + + + Prasad et al. (2012) 2000 mg/L Seed treatment (3 hours) − − − 25 Maize 50–2000 mg/L Seed soaking (3 hours) + + + Subbaiah et al. (2016) <100 Brassica 500–1500 mg/L Seed allowed to grow in treated plain agar for 12 days − − − Zafar et al. (2016) <100 Wheat 500 mg/L Seed treatment (24 hours) + + + Elhaj Baddar and Unrine (2018) n/a Rice 500 and 750 mg/L Seed treatment till germination − − − Sheteiwy et al. (2017) 30–60 Rice 5, 10, 15, 20, and 50 mg/L Seed soaking (1 hour) + + + Panda (2017) 34 Wheat 25, 50, 75, and 100 mg/L Seed priming (24 hours) + + + Munir et al. (2018) 13 Wheat 10, 20, and 50 mg/L Hydroponic supplement (14 days) + + + Awasthi et al. (2017) 100 mg/L − + − 20, 40, and 60 Common Bean 1, 10, 100, and 1000 mg/L Seed priming (20 minutes) + + o Savassa et al. (2018) 5000 mg/L − − − 18 Capsicum 100, 200, and 300 mg/L Applied during imbibition (72 hours) + + + Israel García‐López et al. (2018) 400 and 500 mg/L − − −

      3.2.3 Effects of Seed Treatment on Plant Growth

      Seed treated with ZnO NPs not only protects seeds from microbial infections but also provides Zn to the crops after germination in the easily available form (Masuthi et al. 2009; Farooq et al. 2012). Seed priming with Zn NPs (34 nm) for 24 hours at 100 mg/L increased photosynthetic pigment content by 58% and stomatal conductance by 102% after 65 days of treatment. Moreover, the same treatment increased wheat plant height, tillers per plant, spike length, biomass yield, and grain yield by 16, 69, 87, 58, 36, and 185% respectively (Munir et al. 2018).

      3.2.4 Molecular Mechanisms Involved in Effects of Zn NPs on Seed

      Compare to salt‐based Zn, ZnO NPs can enhance Zn delivery to seeds through the particle‐specific mechanisms. Zhang et al. (2015a) suggested that the seed coat (maize) is a greater barrier to the absorption of Zn from ZnO than from ZnSO₄; therefore, ZnO show less toxicity. Raskar and Laware (2014) also reported for onion seeds Zn NPs treatment (less than 40 mg/L) substantially increased antioxidant enzymes, including guaiacol peroxidase (GPx), catalase (CAT), SOD, and glutathione reductase (GR). Besides, Sedghi et al. (2013) stated that Zn NPs could play a vital role in the biosynthesis of auxin and gibberellin, resulting in a higher germination rate. However, there is optimal concentration for Zn NPs application, concentration too high can reduce the activity of antioxidant or reducing enzymes. Israel García‐López et al. (2018) found that ZnO NPs (18 nm) applied during imbibition and incubated for 72 hours at 100–400 mg/L induced a significant increase in production of peroxidase and ascorbate peroxidase; however, at 500 mg/L these enzymes were reduced in Capsicum. Therefore, it is crucial to determine the optimal Zn NPs concentration and treatment duration

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