The beneficial effects of Si on crops are summarized in Figure 1 below. Most effects of Si are expressed through silica gel, which is deposited on leaves and stems of plants, and some effects are through interaction between silicic acid and other elements such as Al. Currently, there is no evidence showing the involvement of Si in plant metabolism. Therefore, in contrast to essential elements, the function of Si in plants is probably mechanical rather than physiological. This characteristic of Si function explains why Si effects are easily observed in plants that accumulate Si to a certain extent and why Si effects are more obvious under biotic or abiotic stress. With the changes occurring in the global environment, the role of Si will become more and more important for better and sustainable production of crop.