Issue |
Agron. Sustain. Dev.
Volume 28, Number 3, July-September 2008
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Page(s) | 449 - 455 | |
DOI | https://doi.org/10.1051/agro:2007048 | |
Published online | 06 December 2007 |
DOI: 10.1051/agro:2007048
Impact of zinc-tolerant plant growth-promoting rhizobacteria on lentil grown in zinc-amended soil
Parvaze Ahmad Wani, Md. Saghir Khan and Almas ZaidiDepartment of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh-202002; U.P., India
Accepted 18 September 2007 ; published online 6 December 2007
Abstract - Though zinc is a plant nutrient at low levels, Zn ions can be highly phytotoxic at higher concentrations
found in contaminated soils. Plant
growth-promoting rhizobacteria can be used to decrease this toxicity.
Indeed, in addition to their role in plant-growth promotion, rhizobacteria
also reduce the toxicity of heavy metals. In turn, they can be effective for
crops grown in metal-contaminated soils. Here, we isolated a zinc-tolerant plant growth-promoting rhizobacterium, Rhizobium species RL9, from a
zinc-contaminated soil and assayed its plant growth-promoting activities in vitro.
We found that the rhizobacterium strain RL9 tolerated zinc up to a
concentration of 400 g mL-1 on yeast extract mannitol agar
medium. It produced 33
g mL-1 of indole acetic acid in Luria
Bertani broth at 100
g mL-1 of tryptophan and was positive for
siderophore, hydrogen cyanide and ammonia. Such phytohormones released by
this strain could help in promoting the growth of legumes. We further tested
the effect of rhizobacterium strain RL9 on lentils grown in zinc-amended
soil. We found that when the rhizobacterium strain RL9 was added to soil
contaminated with Zn at 4890 mg/kg, lentil dry matter increased by 150%,
nodule numbers by 15%, nodule dry mass by 27%, leghaemogloblin by
30%, seed yield by 10% and grain protein by 8%, compared with
uninoculated plants. We also found that the concentration of zinc was higher
in uninoculated plant organs than in the inoculated counterpart. Our
findings thus suggest that rhizobacterium strain RL9 could be exploited for
bacteria-assisted reduction of zinc toxicity in zinc-contaminated soils due
to its intrinsic abilities of expressing growth-promoting substances and
reduction of the toxic effects of zinc.
Key words: lentil / zinc tolerance / zinc uptake / plant-growth promotion
Corresponding author: khanms17@rediffmail.com
© INRA, EDP Sciences 2008