Sarvjit L. Soni

Electron Microprobe Analysis of the Distribution of Silicon and Other Elements in Rice Leaf Epidermis

Using electron microprobe analysis, significant amounts of silicon were detected in a few long epidermal cells, mostly along their cell walls, in the silica cells, and in the trichomes of both surfaces of the leaf blade and leaf sheath of the rice (Oryza) plant. This analysis did not reveal detectable amounts of silicon in the stomatal apparatuses of these organs. In the ligule, silicon is present in significant quantities in some of the epidermal cells, while in other long epidermal cells no significant amounts of silicon were detected. The effect of accumulation of large quantities of silicon in the long epidermal cells of the ligule on the accumulation pattern of K, Ca, Mg, P, Mn, Fe, and Na is described. This effect of silicon, particularly on the accumulation of potassium, is discussed.

Electron-probe microanalysis of silicon in the epidermis of rice (Oryza sativa L.) internodes.

SummaryElectron-probe X-ray microanalysis showed that significant amounts of silicon are accumulated in the entire epidermal system of the rice internode except in the stomatal apparatuses. Thus, there is a lack of specific sites for Si deposition from levels just above the base to the tip of the rice internode. In the intercalary meristem region, 1 cm above the base of the internode, point-count data indicate more Si accumulation in the dumb-bell shaped silica cells than in the long epidermal cells. Above this region, Si is accumulated essentially in a uniform pattern in all epidermal cells. Such a pattern for Si accumulation in rice internodes markedly contrasts with that for Avena internodes and may explain, in part, why rice plants have a higher percentage Si (dry weight basis) in their shoots. The adaptive significance of this silicification pattern in rice is discussed.

Electron microprobe analysis of silica cells in leaf epidermal cells ofCyperus alternifolius

SummaryElectron microprobe analysis was used to examine relative amounts of selected accessory elements (Ca, Mg, K, Na, P, Mn, and Fe) associated with silicon in silica cells in leaf epidermal cells ofCyperus alternifolius. In the leaf epidermal cells, silicon is localised in significant quantities in silica cells and in a few long epidermal cells. Silicon could not be detected in the stomatal apparatuses. The accumulation of significant amounts of silicon in the silica cell appears to retard the accumulation of K and to enhance the accumulation of Ca, Mg, Mn, Fe, and P. Sodium was detected in very small traces in the silica cells. The possible functional significance of the altered deposition patterns for these elements inCyperus is discussed.