Kazuo Yoneda

Enhancement of Plant Stem Growth by Flocculation of the Antibiotic-producing Bacterium, Pseudomonas fluorescens S272, on the Roots

The antibiotic-producing bacterium, Pseudomonas fluorescens, is assumed to be important in protecting plants from soilborne diseases. S. fluorescens S272, a hyper-producing strain of pyoluteorin (PT) and 2,4-diacetylphloroglucinol (DG), had previously been isolated from soil. The present paper reported that the growth of water-cultivated Kaiware radish was promoted to 120-140% of its normal level by the coaddition of an S272 culture broth (0.01-1% v/v) and a polysaccharide flocculant (1-100 ppm) from Klebsiella pneumoniae H12. Tight adhesion of S272 cells to the root tissue was microscopically observed. The growth promotion is assumed to have been caused by antibiotic effects for the following two reasons: 1) PT (4 mg/l) and DG (24 mg/l) addition to a radish culture enhanced stem growth to 130% of the normal level; 2) a culture solution containing the S272 culture broth (0.01-1% v/v) markedly inhibited the decomposition of hypersensitive chrysanthemum leaves. A soil-cultivation experiment with Gomphrena globosa under natural conditions also exhibited enhanced stem length (160%) by coaddition of the S272 culture broth and H12 polysaccharide. These results suggest that polysaccharide-enhanced adhesion of P. fluorescens S272 cells might be useful for promoting plant growth through the increased antibiotic effect.

Identifing Weeds in Turf Using an Optical Sensor.

本実験は光学的雑草識別センサーを利用して, 広葉雑草の画像処理を行い, 除草作業の自動化について検討したものである.秋季から冬季においては, 越年生のオオアレチノギクなどの広葉雑草, スズメノカタビラなどの細葉雑草, クローバーなどの永年生雑草は, SC70フィルター (700nm以遠の遠赤色光領域を透過) をかけたモノクロCCDカメラで撮影した画像の処理で識別が可能であり, 雑草識別センサーを活用して除草作業を自動的に行いうることが示唆された.一方, 春季には雑草も芝も葉は緑色を呈し, 本システムでは識別は困難であった.