Physiological Roles of Silicon in Photosynthesis and Dry Matter Production in Rice Plants I. Effects of silicon and shading treatments

To investigate the combined effects of silicon application and light intensity on growth characteristics, drymatter production, photosynthetic rate, and transpiration rate, three cultivars (cv. Nipponbare, Koshihikari, Suweon 258) were water cultured, using solutions of + Si (silicon application) and –Si (no-application) under two different light conditions (no shade and shade). Silicon application promoted growth and dry matter production in the three cultivars. The greatest effect was found in a japonica-type cultivar, Koshihikari, grown under the shade condition. Siliconapplication prevented overtranspiration and increased water use efficiency in leaves. This was effective in curbing photosynthetic depression and chlorophyll destruction in aged leaves. The maintenance of photosynthetic activity was regarded as one of the main reasons for the dry matter production increase by silicon application.