SOYBEAN RESEARCH

Soybean [(Glycine max (L.) Merrill]
with its about 40-42 per cent protein and
18-22 per cent oil emerging as one of the
fast growing oilseed crop in the world
(Masciarelli et al., 2014). In India, Malwa
plateau of Central India is the hub for
soybean cultivation, the total production
during 2014 was about 11.64 m t from
10.02 m ha hectare (Anonymous 2014-15).
Although, the spread of soybean in
different parts of the country also
resulted into parallel growth of oil
industry by commissioning solvent
extraction plants, which, apart from
expelling oil, are also earning foreign
exchange through export of deoiled cake
(DOC). But for the past few years
soybean is facing climatic challenges,
with the result the soybean yields are
declining.
Otherwise also, when compared
to other soybean growing countries, the
productivity of soybean is very low in
India. The reasons for lower productivity
are recurrence of drought, the low
nutrient use efficiency of crop, nutrient
deficiency in soil and other biotic and
abiotic stresses. Since soybean is a legume
crop, mainly draw nutrients from native
pool of soil, the incremental applications
of fertilizers are not likely to help in
increasing the productivity of this crop.
Soybean depends on their symbionts for
a large part of their nitrogen
requirements for growth and increased
dry matter production. Therefore, the
approach of using rhizosphere
microorganisms is viable that can fix
atmospheric nitrogen and solubilize and
mobilize phosphorus and other soil
nutrients to stimulate plant growth and
improve soil health. Amongst such
microbes, soybean root nodule forming
rhizobia and mycorrhizal fungi are the
important symbionts associated with
plant roots and known to improve the
plant growth, nodulation and plant
nutrition. Since, both mycorrhizal fungi
as well as rhizobial are commonly found
inhabiting the common rhizosphere and
colonizing the roots of crop plants
including soybean. These arbuscular
mycorrhizal fungi (AMF) forms
symbiotic association and enhances water
and nutrient transport particularly
phosphorus (Xiao et al., 2010; Tajini et al.,
2012), Zn (Chen et al., 2003), N and also
increases growth and yield of many crop
plants (Raverkar and Tilak, 2002). In
recent years, the effect of combined
inoculation with AMF and rhizobia have
been reported to further increase the
growth and yield of some crops including
soybean (Aryal et al., 2006; Meghavansi et
al., 2008; Abd-Alla et al., 2014; Antunes et
al., 2006). The association of
bradyrhizobial strains with the roots of
soybean plants also improves soil health
and nitrogen fixation, thus further
increasing crop production (Van
Jaarsveld et al., 2002). The tripartite
association of symbiotic AMF, root
nodule bacteria Bradyrhizobium japonicum
and soybean host was investigated to
find its effect on the promotion of growth
and yield of soybean (Meng et al., 2015).
These two groups of microbes exert
positive effects on plant growth by
improving P and N availability. Very
recently studies have corroborated a
positive effect of the interactions between
AMF and rhizobial under drought
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