Abstract
The behavior of PGPR (plant growth-promoting rhizobacteria), which promotes the growth of spinach was examined. 1) In the case of the bacterial density of the suspension which soaks the seed being over 10^5 cfu m L^<-1> there was no difference in the bacterial population which adhered to the seed. In addition, there was no remarkable difference within the bacterial density which colonized on the spinach root, though the bacterial density per seed differed. 2) In the case in which the bacterized seeds were preserved at 4℃, the decrease in the bacterial population on the seeds was considerably gentle. The lowering of the bacterial population on the seeds was maintained by soaking the seeds in 10 g L^<-1> methyl cellulose (100 degrees of polymerization). The bacterial population on the seeds was maintained at a high level for a long time (6 months), in the case of methyl cellulose being used. 3) There was no remarkable growth-promoting effect, in the case of the fluorescent pseudomonad being inoculatecl to the spinach in soil culture, while growth-promoting effects of the spinach were observed in hydroponic culture. 4) The lowering of the bacterial population of inoculum was gentle, when rice straw cattle feces compost, sawdust horse feces compost or rice straw horse feces compost were added with the PGPR. The high PGPR population was maintained in the soil with use of these organic materials.
