Role of Mutant Phosphate Solubilizing Microorganism on Growth of Brassica juncea (L.) cv RH 30.

Phosphorus is the second major plant nutrient and the availability of this element to plants is a major challenge due to conversion to insoluble form by chemical reactions with metal cations depending upon the soil pH. Total of sixty eight isolates of phosphate solubilizing bacteria from rhizosphere of mustard grown in different region of Haryana was studied. The isolates were mutagenised by giving treatment of Nitrosoguanidine (50 ug/ml). Three PSB strains (15M, 22M and 25M) and six mutants (15M2, 15M6, 22M28, 22M29, 25M11 and 25M30) were evaluated for their establishment in the rhizosphere, their effect on biomass production in mustard ( Brassica juncea ). Total bacterial count in rhizosphere increased after 30 and 40 days of sowing while decrease in growth was observed at 60 days of sowing. The phosphate solubilizing bacterial count in the rhizosphere varied from 1 to 24, 2 to 20 and 1 to 11 at 30, 45 and 60 days after sowing. Phosphate uptake also increased upto 11-21% which shows thatmutants had significant effect on increase in plant dry biomass and P-uptake under pot house conditions.