RHIZOPLANE MICROORGANISMS OF RICE SEEDLINGS AS EXAMINED BY SCANNING ELECTRON-MICROSCOPY

Rhizoplane microorganisms of water cultured rice seedlings inoculated with soil microorganisms were examined by scanning electron microscopy and optical microscopy. Composition of the bacterial flora on the rhizoplane were also studied. Microorganisms on rhizoplane were limited only in bacteria consisting mostly of rods. They were distributed in every region except the root tip zone. Bacterial aggregations were common at ruptured sites of epidermal cells and cell junctions. They were also dispersed and adhered on mucigel, bare epidermal surface, and root hairs. The area covered with bacteria in the whole root surface was, however, relatively small (1–9%, average 4.6%). Some rhizoplane bacteria were seen to invade into the roots through ruptured sites on epidermis and mucigel. The composition of bacterial flora on rhizoplane was much simpler than that in the paddy soil from which soil inocula were prepared. Pseudomonas and Bacillus occupied about 60 and 40 per cent of the total found in rhizoplane, respectively. On the other hand, bacteria in the paddy soil consisted mostly of 90 per cent Bacillus, and no Pseudomonas was detected. © 1979 Taylor & Francis Group, LLC.