Surface Structure of Unhulled Rice Observed by Scanning Electron Microscope

Abstract

Unhulled seeds and the accessory parts of rice (Oryza sativa var. Aichi asahi) were examined by scanning electron microscopy. The surface topography is described and illustrated in awn, glume, rachilla, empty glume, rudimentary glume and pedicel. Cross sections of glume (hull) were also observed. The detailed structure of glume development in abaxial surface shows the epidermal cells give rise to the trichomes or the minute protuberances fitting tightly between the longitudinal rows of the enlarged epidermal cells (tubercles). The tubercles are about 65 μm in width and have two bulges. This alternate arrangement of the outgrowths and tubercles shows variation in differentiation of epidermal cells. The basal portion of trichome is 30-60 μm in diameter, and the protuberances are 7 μm in width. A hole is at the central portion of the outgrowths. The adaxial surface of glume possesses a number of minute protuberances and rows of stomata. Stomata are 10 μm in length. The minute protuberance in both adaxial and abaxial surfaces of glume consists of two cells. Trichomes arising from the epidermis of the awn, empty glume, rudimentary glume and pedicel are few to many. The above mentioned results confirm the earlier observations by de Haan and Juliano et al.