Role of Microbial Inoculants on Growth and Development of Jatropha curcas L.

Abstract

Microbes play very vital role in the nutrient acquisition to the plants, particularly phosphorus which act as limiting factor for plant growth. The efficiency of microbial flora which includes Azospirillum, Pseudomonas collected from different places was analyzed in phosphate solubilization and nutrient uptake in Jatropha curcas. Besides, VAM population was also studied in all the samples. Potential of these microbes were investigated in field and nursery trials and significant results were observed. Plant microbe interaction was studied thoroughly by several methods using biofertilizers and other phosphate solubilizers (mycoflora). Effect of root exudates on AM fungi colonization was also studied by standard root staining techniques. Positive interaction amongst the flora was recorded in terms of total phosphate solubilization or the enzymes released, total leaf phosphorus content and proteins through SDS-PAGE and spectrophotometric analysis. The small subunit rRNA gene (rDNA) specific for AM fungi was amplified with taxon specific primers (VANS I) paired with universal primer (NS2). Variation in colonized and non colonized PCR product was detected. Colonized roots depicted a 550 bp amplification which was not detected in the uninoculated plant. Results could also be obtained from roots showing 30 % colonization. Root exudates enhanced the population by 80 % while other treatments showed less colonization. Growth, collar diameter, leaf phosphorus and protein content of all the treated plants had a significant variation. Single super phosphate enhanced the growth at the most followed by VAM. Impact of plant microbe interaction on growth and development of J. curcas was also evaluated and maximum effect was recorded from treatment containing mixed culture. Remarkable increase was observed in all the parameters evaluated. The experiment laid out during August 2009, with microbial inoculants significantly enhanced the growth and collar diameter of J. curcas plants as compared with untreated (control) plants.