Nitrogen fixation (C2H2 Reduction) associated with root of sesamum cultivars and its response to inoculation of Azospirillum
2000
Saha, K.C. | Ghosh, T.K. | Ghosh, Mithua Halder (Bidhan Chandra Krishi Viswavidyalaya, Mohanpur (India). Dept. of agricultural Chemistry and Soil Science)
Two separate experiments, in green house and field, were conducted with clay loam soil (Entisol) to study the potentiality of N2 ase activity associated with the roots of six (B-67, IDP-60. HT-1, B-9, B-14 and IS-5) cultivars of sesamum and the effects of seed (cv. B-67) inoculation with an isolate of Azospirillum Lipoferum (IS-5), either alone or mixed with Azotobacter chroococcum, on N2-fixation in rhizosphere, root bacterial association and yield and N content of the crop. The root associative N2 ase activities in the sesamum cultivars were generally low, ranging only from about 32 to 99 nM C2H4 g-1 excise root (dry) day-1. The N2-ase activity of the cultivars was not correlated with the population of microaerophilic bacteria, predominantly Azospirillum Lipoferum, on root surface and in root tissue. Inoculation of an efficient N2-fixing isolate of Azospirillum lipoferum (IS-5), however, resulted a marginal increase in the N-content in rhizosphere soil and significant increase in the seed yield and N-content of field grown crop. Combined inoculation of Azospirillum lipoferum and Azotobacter chroococcum performed better in almost all respect than the A. lipoferum alone in presence of applied N, particularly at the 60 kg N ha-1 level.
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