Agriculture Reference
In-Depth Information
belong to several genera within the class Basidiomycetes, while some belong to the
zygosporic Zygomycetes and Ascomycetes. On the other hand, AM fungi belong to
six genera within the azygosporous zygomycetes
VesicularArbuscularMycorrhiza(VAM)
VAM are common, ancient and most fascinating class of fungi which proves to
be very beneficial to plants (Alizadeh 2011 ). VAM is an endotrophic mycorrhiza
formed by aseptate phycomycetous fungi. They produce an interconnected network
of hyphae between cortical cells that extend to the soil and hence absorb various
nutrients and water (Sally et al. 2011) VAM forms an association with various crop
plants which include monocot, dicot, annual or perennial crops. The use of VAM en-
hances growth of plants in less fertile soils besides application of FYM and cereal-
legume crop rotations. Whereas, application of chemicals mostly fungicide sup-
presses its existence.
Mycorrhiza enhances the feeding areas of the plant root as the hyphae spreads
around the roots. It also mobilizes the nutrients particularly phosphorous that are
present in organic or inorganic form in soil and translocate it to plants with the help
of extensive mycelium. In addition to translocation of phosphorous to plant it also
stores the nutrients and removes the toxic substances for example, phenolics which
otherwise hinder nutrient availability in addition to this it also provides protection
against other fungi and nematodes. VAM also assists in transfer of nutrients other
than phosphorus, like zinc and sulfur Cu (copper), K (potassium), Al (aluminum),
Mn (manganese), Fe (iron) and Mg (magnesium) from the soil to the plant roots.
They act as intracellular obligate fungal endo-symbiont by penetrating the root
cortex (Alizadeh 2011 ). In addition they possess vesicles intended for storage of
nutrients and arbuscular for transferring these nutrients into root system as well as
enhances water absorption. However, in ecto-mycorrhiza, the hyphae cover both
outside and within the root in the intercellular spaces of epidermis and cortex. Trees
are usually found to be infected with ectomycorrhiza, they increase the tolerance of
plants against drought and salt stress, increase the photosynthetic activity of plants,
higher chlorophyll content, higher leaf water potential restored capacity (Wang
1989, 1998 ). VAM helps in soil conservation and soil aggregation, increase the re-
sistance of plants against root-pathogens, increases habitatrestoration (Dodd 2000 ).
Conclusions and Future Prospects
Bio-fertilizers increase crop productivity by increasing availability or uptake of nu-
trients through solubilization or increased absorption stimulation of plant growth
with the help of hormonal action or antibiosis, or by decomposition of organic resi-
dues. Moreover, bio-fertilizers also help to reduce the use of chemical fertilizers
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