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Which one of the following is not a biofertilizer?
A
Mycorrhiza
B
$Agrobacterium$
C
$Rhizobium$
D
$Nostoc$
Detailed Solution
Biofertilisers are organisms that enrich the nutrient quality of the soil; the main sources are bacteria, fungi and cyanobacteria.
$Rhizobium$ fixes atmospheric nitrogen in the root nodules of legumes.
$Nostoc$ (like $Anabaena$ and $Oscillatoria$) is a nitrogen-fixing cyanobacterium.
Mycorrhiza is the symbiotic association of a fungus with roots, which helps the plant to absorb phosphorus.
$Agrobacterium\ tumefaciens$ is a plant pathogen that causes crown gall tumours; it is used as a vector for gene transfer in plants and does not enrich the soil.
Hence $Agrobacterium$ is not a biofertiliser.
$Rhizobium$ fixes atmospheric nitrogen in the root nodules of legumes.
$Nostoc$ (like $Anabaena$ and $Oscillatoria$) is a nitrogen-fixing cyanobacterium.
Mycorrhiza is the symbiotic association of a fungus with roots, which helps the plant to absorb phosphorus.
$Agrobacterium\ tumefaciens$ is a plant pathogen that causes crown gall tumours; it is used as a vector for gene transfer in plants and does not enrich the soil.
Hence $Agrobacterium$ is not a biofertiliser.