Multifarious native plant growth promoting fluorescent pseudomonads associated with rhizosphere of Aloe barbadensis miller

Medicinal plants provide an enormous bioresource of potential use in modern medicine and agriculture. Phosphorous deficiency is a major constraint to plant production. Sustainable agriculture could be promoted by harnessing the plant beneficial bacteria particularly the fluorescent pseudomonads associated with the rhizosphere of plants, to mobilize soil inorganic phosphate and also to increase its bioavailability to the plants. Total five hundred seven fluorescent Pseudomonas isolates were obtained from four different Aloe barbadensis (Miller) growing locations of Varanasi. These Pseudomonas strains were further evaluated in vitro for their ability to solubilize phosphate and to produce indole acetic acid (IAA), hydrogen cyanide (HCN), siderophore and aminocyclopropane (ACC) deaminase. Total 119 fluorescent Pseudomonas isolates from the rhizospheric soil (RS) and 25 isolates from the endorhizosperic (ER) region solubilized phosphate.Whereas 53 (36.8%) Pseudomonas isolates produced IAA and siderophore, 36(25%) and 31 (21.5%) isolates, however, produced HCN and ACC deaminase. Out of 119 phosphate solubilizing bacteria (PSB) from RS region, 51 (42.9%) isolates and 9 (36%) isolates out of 25 PSBs from ER region lacked plant growth promoting traits (PGPTs). Among the phosphate solubilizing fluorescent pseudomonads showing PGPT, 59 isolates have multiple traits and showed more than two types of PGPT. A positive correlation exists between siderophore and ACC deaminase producers. Clustering by principal component analysis (PCA) showed that RS was the most important factor influencing the ecological distribution and physiological characterization of PGPT- possessing PSB. Geographical Information System (GIS) and Kriging Interpolation method was used to map and establish spatial variation of soil properties of the study site.