The comparison of growth parameter and pigments content of bean (Phaseolus vulgaris L.) plants inoculated with various Kerman indigenous rhizobacteria

Nitrogen deficit is one of the most limiting nutrients for plant production. Therefore, identifying diazotrophic indigenous inoculants to promote nitrogen fixation have a great importance in agriculture. In the current study, a number of rhizobacteria isolated from nodules of different legumes cultured in Kerman (IRAN) province. Isolates were screened for their ability to grow on N-free media. Eight isolates showed the best growth speed on on N-free media selected for further experiments. The reminders with little speed grow on medium were discarded. The selected isolates were analyzed in vitro for diazotrophic potential tests for ammonia production. The effect of isolates on some growth parameters and nodulation of bean plants were also studied under greenhouse conditions by 10 treatments including N and N-free groups. All selected isolates significantly (P<0.01) enhanced growth parameters of bean plants above the un-inoculated N-free control. Chlorophyll a was also raised in the presence of rhizobacteria inoculation which the content was as much as the group treated by mineral N application. Its total chlorophyll content was also the highest after mineral N treated group. Among isolates, MPV2 followed by GMS with the highest number of root nodulation showed the greatest impact on growth characteristics such as plant height and leaf water content. MCA and GMS isolates had the most nitrogen content in plants comparing to the rest of groups. It can be concluded from the results that MPV2, GMS and MCA, respectively collected from root nods of Phaseulus vulgaris, Medicago sativa and Cicer arietinum plants are good candidates for improving bean plants growth production as N-fixator biofertilizers. However, the beneficial of these isolates should be screened under field conditions for P. vulgaris plants.