Although the bulk of silicon research has been dedicated to monocot species (categorized as “silicon accumulators”), the beneficial effects of silicon, lists of crops benefiting from silicon supplements, and isolation of silicon’s mode-of-action continues to expand. Silicon
Research Summaries on Dicotyledonous Crops by Dr. Mary Provance-Bowley, Ph.D.
Introduction Silicon (Si) has been recognized as being an essential nutrient for the Equisetaceae (Chen and Lewin, 1969; Hoffman and Hillson, 1979); Bacillariophyceae (Raven, 2003), wetland Poaceae (Pilon-Smits et al., 2009), and Cyperaceae; evidenced as 
being essential for beets (Raleigh, 1939) an “agronomically essential’ (improving fitness and agricultural productivity) element for others such as rice and sugarcane (Cheng, 1982, Fox and Silva, 1978; Haysom and Ostatek-Boczynski, 2006; Kamenidou et al., 2008; Kamenidou et al., 2010; Ma, 2004; Savant et al., 1997; Savant et al., 1999); and a “quasi-essential” element (deficiency causing growth, development and reproductive abnormalities; Epstein, 1999) or “beneficial substance” (official in 2013; AAPFCO, 2014. However, essentiality has not been established for all plant species based on the guidelines established by Arnon and Stout (1939).
Silicon (Si) has been recognized as being an essential nutrient for the Equisetaceae (Chen and Lewin, 1969; Hoffman and Hillson, 1979); Bacillariophyceae (Raven, 2003), wetland Poaceae (Pilon-Smits et al., 2009), and Cyperaceae; evidenced as being essential for beets (Raleigh, 1939) an “agronomically essential’ (improving fitness and agricultural productivity) element for others such as rice and sugarcane (Cheng, 1982, Fox and Silva, 1978; Haysom and Ostatek-Boczynski, 2006; Kamenidou et al., 2008; Kamenidou et al., 2010; Ma, 2004; Savant et al., 1997; Savant et al., 1999); and a “quasi-essential” element (deficiency causing growth, development and reproductive abnormalities; Epstein, 1999) or “beneficial substance” (official in 2013; AAPFCO, 2014. However, essentiality has not been established for all plant species based on the guidelines established by Arnon and Stout (1939). True grains and pasture grasses are all monocot species and “for most of the world’s population, grain is the primary source of nutrition” (Kendall and Pimentel, 1994). So, one could assume that when conducting research on a newly suspected plant nutrient, that the first crops to be studied would be the most agronomically important ones. This has proved to be the case with initial and extensive research focused on monocot grain species such as rice (Oryza sativa L.). Rice is categorized as a “silicon accumulator” (Ma et al., 2001). However, when plant species were initially separated into classes as accumulating, intermediate or nonaccumulating, researchers analyzed only shoot silicon content, which ranged from 0.1 to 10%, and not root concentrations. And, even with the grain driven focus being mainly on the shoots of monocot species, eight species of Cucurbitales, dicots, were determined to be intermediate. Tomatoes (Solanaceae), initially classified as “silicon excluders”, have shown Si deficiency symptoms during reproduction; after the first bud flowering stage (Miyake and Takahashi, 1978). These observations revealed that tomato plants may bloom, but can fail to pollinate and often either bear no fruit at all, or the fruit that forms is malformed under Si-free conditions.