Isolation of Plant growth promoting rhizo bacteria from rhizosphere soils of green gram , biochemical characterization and screening for antifungal activity against pathogenic fungi
- K . Geetha, A . B . Rajithasri, B . Bhadraiah
This research was undertaken for the purpose of isolation and purification of indigenous Pseudomonas spp. and evaluating its ability in hydrogen cyanide synthesis and also evaluating the potential of super-strains on seedling growth inhibition in weeds. According to this, the research was carried out in laboratory tests. 136 strains (obtained from rhizosphere soil of 62 weed species) and 27 strains of Pseudomonas fluorescence were sub-cultured, purified and refreshed. Then these strains were evaluated for the capability in cyanide synthesis by a qualitative method and at last 4 super-strains of cyanogenic Pseudomonas were selected and used in further experiments. The effects of these strains on stem length, root length and stem length/root length rate in rye, wild barley, and wheat were evaluated in three different in vitro tests examining the effects of gas and liquid metabolites produced by the bacteria. The results showed that the abundance and probability of the bacteria isolation was low (about 3.6%). About 37 percent of Pseudomonas isolates were capable of HCN production and this capacity was different among the strains. Gas metabolites reduced more than 90 percent of root and shoot growth in weeds. In this case gas metabolites had greater inhibitory effects rather than other metabolites on plants. However these influences were different in every bacteria treatment. Also wheat had less growth reduction in comparison with weeds which probably mean that the bacteria are plant specific. In conclusion, achievements proved that cyanogenic pseudomonas fluorescence had the potential of biological weed control. However the further studies about their application in natural conditions like greenhouse, and field seem to be necessary.