Growth promotion of maize by desiccation tolerant Micrococcus luteus-chp37 isolated from Cholistan desert, Pakistan

Present study deals with the isolation and characterization of desiccation tolerant bacteria Micrococcus luteus-chp37 from rhizosphere of plant growing in the Cholistan desert of Pakistan. To check the desiccation tolerance, strain was incubated at various levels of relative humidity (5, 27 and 100%) for a period of 6, 12 and 18 days. The surviving fractions of M. luteus-chp37 after 18 days of desiccation, under RH 5, 27 and 100% were 2, 4 and 0.6%, respectively. M. luteus-chp37 incubated under RH 5% and 100% lost its viability at much faster rates as compared to RH 27%. To check the plant growth promoting ability of this strain, pot experiments with Zea mays (under sandy and pure field soil) were conducted and various growth parameters (germination, root and shoot length, number of leaves, dry weight per gram fresh weight, chlorophyll contents) were measured after 90 days maize plants. M. luteus-chp37 inoculation resulted 8.5, 13, 23 and 54% increases in number of leaves, shoot length, root length and dry weight g fresh weight, respectively, as compared to un-inoculated control maize plants. Beside this there were 159, 80, 84% and increase in chlorophyll a, chlorophyll b and total carotenoids respectively in pure field soil. This growth promotion was attributed as a result of production of plant growth promoting substances cytokine and hydrogen cyanide.