as phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase, and catalase),
malondialdehyde, hormones, and changes in gene expression pattern (Kim et al.
2011, 2014, 2016; Hajiboland et al. 2017; Hall et al. 2019).
2.4.8 High pH Stress
Over the last century, due to the continuous anthropogenic activities and farming,
there has been a paradigm shift in the pH of soil which either results in acidic or
alkaline conditions (Wang et al. 2017; Shen et al. 2019). This pH changes in the pH
of soil affect not only the plant roots but their functionality too. As a result of it,
many modifications are induced frequently in the root and shoot physiology due to
change in the pH of the xylem sap. Even in this regard, exogenous application of
silicon has also resulted in alleviating the effects of pH stress on many plants (Abdel
Latef and Tran 2016; Wang et al. 2017; Liu et al. 2018; Khan et al. 2019; Ju et al.
2020) (Table 2.2).
2.5
Necessity of Silicon in Agriculture
With increasing incidences and severity of climate change, the challenges to the crop
production will also increase in a long way to the future (Mahmoud and Gan 2018;
Tamburino et al. 2020). This will be truly reflected in the form of more and more
cases of diseases, pest attack, salinity, and drought conditions (Bashyal 2018; Rathee
and Dalal 2018; Balamurugan et al. 2019; Shiru et al. 2020). Moreover, the
intensified cum successive cropping has resulted in the elimination of basic cations
from the soil (Jaiyeoba 2003; Xiao et al. 2013; Hao et al. 2019; Macedo et al. 2020).
In addition, the continuous fertilization by the farmers necessitates the liming
programs for maintenance of yields (Tubana et al. 2016; Hao et al. 2019; Xu et al.
2020). In this case, the high liming potential of silicon sources like silicate slags
serves as a good agronomic option to correct soil pH (Tubana et al. 2016; Keeping
et al. 2017; Etesami and Jeong 2018; Haynes 2019). In addition, many silicon and
fertilizers act as a low-cost, good source of some important nutrients in plants such as
Ca
2+ and Mg
2+ as well as fertilization enhance uptake of N, P, and K (Tubana et al.
2016; Zhao et al. 2020). Furthermore, various silicon sources that are being
employed are actually low-cost byproducts from industries (Chanchal Malhotra
et al. 2016). Even in few cases, many farmers have used straws of wheat and rice
straw along with other small grain crops as a potential Si source (Marxen et al. 2016;
Seleiman et al. 2019). Additionally, there are many reports on a foliar spray of Si
containing solution (Haynes et al. 2013; Rodrigues et al. 2015; Oliveira et al. 2019).
In the recent past, many liquids as well as granulated forms of Si fertilizers have been
also generated due to the advances in the field of nanotechnology (Tubana et al.
2016; Rastogi et al. 2019; Siddiqui et al. 2020). These nano-size scale highbioavailability fertilizers easily penetrate and create a thick-silicate layer on the
surfaces of leaves (Chanchal Malhotra et al. 2016; Siddiqui et al. 2020). All these
32
S. Mehta et al.
malondialdehyde, hormones, and changes in gene expression pattern (Kim et al.
2011, 2014, 2016; Hajiboland et al. 2017; Hall et al. 2019).
2.4.8 High pH Stress
Over the last century, due to the continuous anthropogenic activities and farming,
there has been a paradigm shift in the pH of soil which either results in acidic or
alkaline conditions (Wang et al. 2017; Shen et al. 2019). This pH changes in the pH
of soil affect not only the plant roots but their functionality too. As a result of it,
many modifications are induced frequently in the root and shoot physiology due to
change in the pH of the xylem sap. Even in this regard, exogenous application of
silicon has also resulted in alleviating the effects of pH stress on many plants (Abdel
Latef and Tran 2016; Wang et al. 2017; Liu et al. 2018; Khan et al. 2019; Ju et al.
2020) (Table 2.2).
2.5
Necessity of Silicon in Agriculture
With increasing incidences and severity of climate change, the challenges to the crop
production will also increase in a long way to the future (Mahmoud and Gan 2018;
Tamburino et al. 2020). This will be truly reflected in the form of more and more
cases of diseases, pest attack, salinity, and drought conditions (Bashyal 2018; Rathee
and Dalal 2018; Balamurugan et al. 2019; Shiru et al. 2020). Moreover, the
intensified cum successive cropping has resulted in the elimination of basic cations
from the soil (Jaiyeoba 2003; Xiao et al. 2013; Hao et al. 2019; Macedo et al. 2020).
In addition, the continuous fertilization by the farmers necessitates the liming
programs for maintenance of yields (Tubana et al. 2016; Hao et al. 2019; Xu et al.
2020). In this case, the high liming potential of silicon sources like silicate slags
serves as a good agronomic option to correct soil pH (Tubana et al. 2016; Keeping
et al. 2017; Etesami and Jeong 2018; Haynes 2019). In addition, many silicon and
fertilizers act as a low-cost, good source of some important nutrients in plants such as
Ca
2+ and Mg
2+ as well as fertilization enhance uptake of N, P, and K (Tubana et al.
2016; Zhao et al. 2020). Furthermore, various silicon sources that are being
employed are actually low-cost byproducts from industries (Chanchal Malhotra
et al. 2016). Even in few cases, many farmers have used straws of wheat and rice
straw along with other small grain crops as a potential Si source (Marxen et al. 2016;
Seleiman et al. 2019). Additionally, there are many reports on a foliar spray of Si
containing solution (Haynes et al. 2013; Rodrigues et al. 2015; Oliveira et al. 2019).
In the recent past, many liquids as well as granulated forms of Si fertilizers have been
also generated due to the advances in the field of nanotechnology (Tubana et al.
2016; Rastogi et al. 2019; Siddiqui et al. 2020). These nano-size scale highbioavailability fertilizers easily penetrate and create a thick-silicate layer on the
surfaces of leaves (Chanchal Malhotra et al. 2016; Siddiqui et al. 2020). All these
32
S. Mehta et al.