Colonization of micropropagated sugarcane plants by Gluconacetobacter diazotrophicus
and Herbaspirillum sp. was confirmed by a dot-immunoblot assay. In all, a 45-
day short-term and 180-day long-term experiments conducted on micropropagated
sugarcane plants of Co 86032, a sugar rich popular variety in South India, indicated
the usefulness of these diazotrophs as plant growth promoting bacteria. Coinoculation
of these two bacteria enhanced the biomass considerably under Nlimited
condition in the short duration experiment. In the long-term experiment, the
establishment of inoculated Herbaspirillum sp. remained stable with the age of the
crop up to 180 days, while there was a reduction in population of G. diazotrophicus
for the same period. The total bio-mass and leaf N were higher in plants inoculated
with G. diazotrophicus and Herbaspirillum sp. without N fertilization and also in
plants with 50% of the recommended N (140 kg ha1) than the plants fertilized with
recommended dose of inorganic N (280 kg ha1). This experiment showed that
inoculation with these bacteria in sugarcane variety Co 86032 could mitigate
fertilizer N application considerably in sugarcane cultivation.
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