Efficacy of Pseudomonas chlororaphis subsp. aurantiaca SR1 for Improving Productivity of Several Crops

Abstract

The recognition of plant growth-promoting rhizobacteria (PGPR) as potentially useful for stimulating plant growth and increasing crop yield has evolved over the past years. Currently, researchers are able to successfully use them in field experiments. The use of PGPR offers an attractive way to supplement or replace chemical fertilizers and pesticides. Most of the isolates cause a significant increase in plant height, root length and dry matter production of plant shoot and root. Some PGPR, especially if they are inoculated on seeds before planting, are able to establish on roots. Also, PGPR can control plant diseases. These bacteria are a component of integrated management systems, which use reduced rates of agrochemicals. Such systems might be used for transplanted vegetables in order to produce more vigorous seedlings that would be tolerant to diseases for at least a few weeks after transplanting to the field (Kloepper et al., 2004). Commercial applications of PGPR are being tested and are frequently successful. However, a better understanding of the microbial interactions that result in plant growth enhancements will greatly increase the success of field applications (Burr et al., 1984). In the last few years, the number of identified PGPR has been increasing, mainly because the role of the rhizosphere as an ecosystem has gained importance in the functioning of the biosphere. Several species of bacteria like Pseudomonas, Azospirillum, Azotobacter, Klebsiella, Enterobacter, Alcaligenes, Arthrobacter, Burkholderia, Bacillus and Serratia have been reported to enhance plant growth. Of these, the genera that are predominantly studied and increasingly marketed as biological control agents include Bacillus, Streptomyces and Pseudomonas (Glick, 1995; Joseph et al., 2007; Kloepper et al., 1989; Okon & Labandera-Gonzalez, 1994).