PGPR can affect plant growth indirectly or directly. Indirect promotion of plant growth occurs when PGPR lessens or prevents the deleterious effects of pathogens. Direct promotion of plant growth involves either the provision of nutrients or the facilitation of uptake of certain nutrients from the environment (Glick 1995). Reithner et al. (2007) reported that Trichoderma atroviride strain P1 promoted the growth of cucumber seedlings infected by R. solani due to an indirect effect (prevention of exposure to the pathogen) not a direct effect (promotion of plant growth). In the pot experiment, significant differences in the length and dry weight of shoots were found between plants treated with N and CK2, but differences were not observed between plants treated with N and CK1. These results indicated that the promotion effect of N43 was mainly an indirect effect ( Table 2).