• A V Rao

      Articles written in Proceedings – Plant Sciences

    • Effect of water stress on nodulation and nitrogenase activity of guar (Cyamopsis tetragonoloba (L.) Taub.)

      B Venkateswarlu A V Rao A N Lahiri

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      The effect of water stress on nodulation and nitrogenase activity of guar (Cyamopsis tetragonoloba (L.) Taub.) was studied at both vegetative and flowering stages. Stress did not induce any change in the nodule number but caused a significant reduction in nodule fresh weight. Drought-induced reduction in nitrogenase activity was observed at both the stages. Upon rewatering, rapid recovery in the activity was noticed which seems to be related to the adaptation of this legume to and regions.

    • Interactions between the root exudates of pearl millet andAzospirillum brasilense

      B Venkateswarlu A V Rao

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      Root exudates of different pearl millet varieties showed quantitative differences in organic carbon, reducing sugars, total and amino nitrogen. The growth and nitrogenase activity ofAzospirillum were stimulated by the addition of root exudates in the culture medium. Root exudates were also found to support the growth ofAzospirillum in the rhizosphere. Inoculation withAzospirillum significantly enhanced the root exudation in axenically grown pearl millet plants accompanied by an increase in the permeability of roots. N2-ase activity of the inoculated plants differed among the varieties and was related to the amount of organic carbon released in the exudates. Addition of extraneous carbon source significantly increased the nitrogenase activity of the roots as the carbon compounds provided by the root exudates appear to be inadequate for the optimum expression of nitrogenase activity. The implications of these results in the pearl millet-Azospirillum association were discussed.

    • Nitrogenase activity of pearl millet—Azospirillum association in relation to the availability of organic carbon in the root exudates

      A V Rao B Venkateswarlu

      More Details Abstract Fulltext PDF

      There were significant differences in the amount of organic carbon exuded by the roots of different pearl millet varieties. The nitrogenase activity of the axenically grown pearl millet varieties inoculated withAzospirillum was related to the quantity of organic carbon released by their roots. However, the amount of exudate was found to be inadequate for the optimum expression of N2-ase activity which was considerably enhanced following the addition of carbon source. The stimulation of activity varied with the type of a carbon source and was related to preference shown by the organism for its growth in vitro. There was no significant change in the total plant dry weight following the addition of carbon to the root zone but there was a marginal reduction in the root growth and the root/shoot ratio.

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