With respect to the physiological function, the resistance responses
conferred by high silicon indicates that it could reduce the
number of nymphs becoming adults, adult longevity and female
fertility of whitebacked planthoppers (Salim and Saxena, 1992).
Here, a similar phenomenon was observed and this could possibly
be designated as an antibiotic factor. An antixenotic factor was also
detected in the susceptible and resistant rice lines when treated
with high silicon solutions. In addition, there were another two
resistance mechanisms including physical and chemical defenses,
by which silicon was likely to increase resistance to herbivore
feeding habits. As for physical resistance, this involved reduced
digestibility and increased hardness and abrasiveness of plant tissues
because of silica deposition which is mainly as opaline phytoliths
comprising the bulk of a plant's Si content in various plant
tissues (Jones and Handreck, 1967; Reynolds et al., 2009). The silicon
on the surface of leaves in corn plants was positive in the
management of Spodoptera frugiperda (Lepidoptera: Noctuidae)
(Pereira et al., 2005). Moreover, by observing the micro-structure of
plant tissues, it was found that the rice cultivars with high density
and large volume of silica in their cells showed higher resistance
against small brown planthoppers (Laodelphax striatellus Fallen;
Zheng et al., 2009). Furthermore, other evidence indicated that