RA 00048.pdf - OAR@ICRISAT

Nitrogen-fixing Bacteria Associated with Sorghum
D. B. Godse. P. J. Dart, and K. P. Habbar
Abstract
The total number of N 2 fixers from rhizosphere soil, rhizoplane and root macerate of sorghum plants was estimated by
plate counts using N-free sucrose and malate media. Using these inocula, nitrogenase activity was measured by the
most probable number (MPN) method on sucrose and malate semisolid media. Nitrogenase activity was measured by
the acetylene reduction technique. Value of the spermosphere model was demonstrated with plants grown in tubes
on Fahraeus agar medium for selection of the most abundant and host compatible bacteria from the rhizosphere soil,
rhizoplane soil and root macerate. Based on colony morphology, various isolates were picked up from plates and
purified. Purified isolates were tested for nitrogenase activity on malate and sucrose semisolid media with 2 0 %
acetylene incubated for 3 hr at 33°C. Applicability of analytical profile index (API) tests was demonstrated for quick
identification of nitrogen fixers belonging to Enterobacteriacae.
A New Sorghum Program in the SAT in Australia
L J. Wade
Abstract
A research program is being initiated to investigate sorghum productivity in the Capricornia region of Queensland,
Australia. This region of expanding dryland sorghum production is characterized by heavy cracking clay soils in the SAT
where antecedent soil moisture is important and rainfall irregular. There is enormous potential for the crop in this
region but performance of existing cultivars has been disappointing so far. Initial experimentation will be directed to
defining the exact nature of limitations to productivity in this environment. Other work will involve phenology, crop
establishment and growth analysis, which are all likely to be important in this region.
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