Studies on association of arbuscular mycorrhizal fungi with gluconacetobacter diazotrophicus and its effect on improvement of sorghum bicolor (L.)

M Meenakshisundaram & K Santhaguru / Int J Cur Sci Res. 2011; 1(2): 23 - 30.

tubaeformis, Glomus fasciculatum, Glomus mosseae, Glomus
macrocarpum, Scutellospora heterogamma and Sclerocystis
pachycaulis , Glomus fasciculatum was found to be the best root
colonizer with 83% colonization in S.bicolor (Table-2). In contrast,
Scutellospora heterogamma was found to be the poor root
colonizer with 20% in S.bicolor. All the species of AM fungi
produced vesicular infection but not produced arbuscular
infection during the study period. AM infection was also
significantly higher in dual inoculated with G.diazotrophicus +
Glomus fasciculatum with 95% colonization in S.bicolor. In
contrast, G.diazotrophicus + Scutellospora heterogamma was
found to be the poor root colonizer with 24% in S.bicolor. (Table-
2).

Table 2. Effect of AM fungi and Glucoanacetobacter diazotrophicus
inoculation on per cent infection in roots of Sorghum bicolor grown in
sterile- soil sand mixture at 35 DAI.

* Average of 3 experiments.

3.4.Effect of AM fungi and G.diazotrophicus inoculation on S.bicolor

The results on fresh and dry matter yield of S.bicolor inoculated
with AM fungi are presented in Table-3. The dual inoculation
increased the fresh and dry matter yield of plants over single
inoculation with either AM fungus or G.diazotrophicus and
uninoculated control. This increase was more pronounced in the
case of G.fasciculatum + G.diazotrophicus and G.mosseae +
G.diazotrophicus.

Impact of AM fungi inoculation enhanced the nitrogen content in
S.bicolor, as compared to the uninoculated control (Table-3). The
nitrogen content increased significantly in mycorrhizal plants in the
presence of G.diazotrophicus. Among the dual inoculated plants, the
microbial effect was substantially higher in G.fasciculatum +
G.diazotrophicus combination. In contrast, the microbial effect was
least with Scutellospora heterogamma + G.diazotrophicus
combination.

Dual inoculation with AM fungi and G.diazotrophicus enhanced
the phosphorus content of S.bicolor over the other treatments viz
uninoculated control, G.diazotrophicus treatment and AM fungi
treatment (Table-3). Within the mycorrhizae alone inoculated
plants, the inoculation effect was much significant in plants treated
with G.fasciculatum and G. mosseae. Further, phosphorus
accumulation was substantially higher in all the mycorrhizal plants
in the presence of G.diazotrophicus.

AM fungi inoculation induced an increase in soluble sugars in
S.bicolor as compared to G.diazotrophicus inoculation or
uninoculated control (Table-4). There was little difference in
soluble sugars between dual inoculated AM plants and singly
inoculated AM plants. However, in the case of G.diazotrophicus +
G.fasciculatum combination, the soluble sugar content was 12.5%
higher than the plants inoculated with G.fasciculatum alone.

In general, dual inoculation significantly increased the
chlorophyll content in leaves of S.bicolor, as compared to the control
and single inoculation with either G.diazotrophicus or AM fungal
species. Among the singly inoculated plants, the AM effect on
chlorophyll content was higher with four species viz Glomus
fasciculatum, Glomus mosseae, Glomus dimorphicum and G.
tubaeformis, in contrast to lower effect with Scutellospora
heterogamma and Sclerocystis pachycaulis. Within the dual
inoculated plants, the diazotroph effect was much pronounced
when it combined with Glomus fasciculatum. However, the
diazotroph effect was poor in combination with Scutellospora
heterogamma .

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