Growth Promotion of Spinach by Fluorescent Pseudomonas Strains under Application of Organic Materials

Abstract

We investigated whether the colonization of spinach roots by fluorescent Pseudomonas strains was promoted by the application of organic materials. Firstly, the bioluminescence (lux) gene was introduced into fluorescent Pseudomonas strains, and the colonization of on spinach roots by fluorescent Pseudomonas strains was observed using a CCD (charge-coupled device) camera. As a result, various organic materials were found to promote the colonization of spinach roots by fluorescent Pseudomonas strains. H3-4 strain colonized the roots when oat straw and betaine monohydrate, rice husks, Japanese pampas grass and horse feces compost (with rice straw) were applied. D23-2 strain colonized the roots when hippuric acid sodium salt, Japanese pampas grass, oat straw, horse feces compost (with rice straw) and trehalose dehydrate were applied. H23-1 strain colonized the roots when cattle feces compost (with rice straw), horse feces compost (with sawdust), Japanese pampas grass, betaine monohydrate, oat straw, horse feces compost (with rice straw) and hippuric acid sodium salt were applied. The organic materials (cattle feces compost (with rice straw), horse feces compost (with sawdust), Japanese pampas grass, betaine monohydrate or horse feces compost (with rice straw)) and fluorescent Pseudomonas (HS23 strain) were applied to soil, and spinach was cultivated. The growth of spinach was promoted when fluorescent Pseudomonas strains and organic materials except for Japanese pampas grass were applied. Since the growth of spinach was not promoted when only the organic materials were applied, this growth-promoting effect was considered to be due to the fluorescent Pseudomonas strains that colonized the roots more readily when the organic materials were applied. In conclusion, the growth-promoting effect of fluorescent Pseudomonas strains was demonstrated in soil culture by the application of fluorescent Pseudomonas strains and organic materials, which promoted root colonization by fluorescent Pseudomonas strains.