Evaluation of non symbiotic nitrogen fixation by bradyrhizobium in cowpea
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Date
1997
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Department of Plant Pathology, College of Horticulture, Vellanikkara
Abstract
A study was conducetd at the College of Horticulture, Vellanikkara during the
year 1993-95 on the evaluation of non-symbiotic nitrogen fixation by
Bradyrhizobium in cowpea. Twelve isolates collected from different agroclimatic
regions of Kerala, two exotic isolates and one KA U isolate were used for the study.
First, a pot culture experiment was conducted to screen the above 15 isolates for their
efficiency in non symbiotic nitrogen fixation. Two media and two methods of
application were also tried. A second pot culture experiment was also conducted to
find out the most suitable method of application of the best performer in terms of
foliar nitrogen fixation.
The results of the screening experiment showed that no particular isolate was
effective in improving any of the parameters observed. However,out of the ten
characters studied, isolate liS (KAU isolate) ranked best in improving five characters
namely, plant height, number of leaves, dry weight of nodule, fresh weight of plants
and nitrogen content. Thus 115 was selected as the promising isolate for the second
experiment. Isolate 114 (CB-7 56), which showed next better performance in improving
number of leaves, dry weight of nodules and fresh weight of plants was also selected.
Moreover, it was one of the known exotic isolates supporting non-symbiotic
nitrogenase activity. The results of the second experiment clearly established the
superiority of seed (soil) inoculation (AI) of Bradyrhizobium over different methods
of foliar application. However, foliar applications also showed improved performance
over control plants in improving the different parameters observed. Spraying the
bacteria grown in broth shake culture (A3) was found effective in improving the
number of leaves, dry weight of roots, chlorophyll content and nitrogen content of
plant. The study show that, eventhough less efficient, the foliar application of
Bradyrhizobium can also be resorted to in improving the performance of cowpea
plants in situations where seed (soil) inoculation is not possible.
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Citation
171421