Nanotechnology by Ram Prasad Manoj Kumar & Vivek Kumar

Author:Ram Prasad, Manoj Kumar & Vivek Kumar
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

9.4 Nanomaterials Based on Metals Essential for Plant Growth

9.4.1 Iron-Based Nanomaterials

Iron (Fe), an essential micronutrient for plants, plays crucial role in several metabolic processes, including photosynthesis, respiration and DNA synthesis. Fe is also involved in the synthesis of Chl and required for the maintenance of the structure and function of chloroplasts, and thus it is indispensable for healthy plant development (e.g. Marschner 1995; Rout and Sahoo 2015). However, in calcareous soils, in which Fe occurs in insoluble oxidized form, its availability is low (Guerinot and Yi 1994), and Fe-deprived plants are usually chlorotic due to the inhibition of Chl synthesis, and their growth is inhibited. Because iron deficiency in humans belongs to the most prevalent nutritional problems in the world today (Scrimshaw 1991; Stoltzfus and Dreyfuss 1998), fertilization with suitable formulations containing Fe in available form is desirable and helpful for healthy plant growth; however for the important staple crop such as rice, it is also necessary to develop Fe-rich plants using conventional breeding or directed genetic modification (Sperotto et al. 2012; Bashir et al. 2013). However, application of high concentrations of Fe ions is phytotoxic resulting in the inhibition of photosynthetic electron transport (Kráľová et al. 2008) and ROS formation causing damage of vital cellular constituents (e.g. membranes) due to lipid peroxidation (Hendry and Brocklebank 1985; Becana et al. 1998). The role of Fe in plant growth and metabolism was comprehensively reviewed by Rout and Sahoo (2015).

Both soil and foliar application of FeNPs to Solanum tuberosum plants exhibited superior effect on the quantitative and qualitative traits of potato than the treatment with Fe chelate; however, the combined treatment using foliar application of amino acids and soil application of FeNPs showed the best results in the percentage of protein, the percentage of Fe, the mean weight of a single tuber and the economic yield (Pourali and Roozbahani 2015).

Joseph et al. (2015) investigated the effects of artificially aged enriched biochar-mineral complexes with higher mineral content, surface functionality, exchangeable cations, high concentration of magnetic FeNPs and higher water-extractable organic compounds on the mycorrhizal colonization, T. aestivum growth and nutrient uptake and soil quality improvement. The application of 100 kg/ha of such formulations resulted in significantly greater uptake of P and N by wheat shoots and consequently in enhanced growth of plants. Enhanced growth could be connected with increased phosphorus uptake by plants, which could be connected with an increase in mycorrhizal colonization as well as with the properties of the biochar-mineral complexes. Also iron oxides (FeOx) NPs were reported as effective nanofertilizers that significantly stimulated the growth of lettuce seedlings when applied at concentrations <50 ppm (Liu et al. 2016). Libralato et al. (2016) evaluated the effects of ionic FeCl3 (1.29–1570 mg/L), as well as micro- (1.71–10.78 mg/L) and nanosized zerovalent iron (nZVI) (4.81–33.560 mg/L) on seed germination, seedling elongation, germination index and biomass of Lepidium sativum, Sinapis alba and Sorghum saccharatum and observed stimulation with application of the highest micro-Fe and nano-Fe concentrations, indicating that these Fe forms are more bioavailable than ionic Fe at these concentrations and act as micronutrient.

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