This study was conducted to evaluate the effect of seed Rhizobia-treating
and Cowpea severe mosaic virus (CPSMV) inoculation on bacterial nodulation
and nitrogen fixation in cowpea. CPSMV was isolated from infected plants,
College of Agriculture,
Abu-Ghraib, Baghdad, IRAQ, the Rhizobia was isolated
from nodules on roots of cowpea plants. The plants were inoculated by the
virus 2 weeks after germinations. Nodules on roots of Rhizobia-treated plants
were formed while no nodules were observed on non-treated ones. The mean
number of nodules was 24.93\ plant on virus inoculated plants compared to
59.86 nodules\plant on non-inoculated ones. Significant reduction in nodules
weight was induced by the virus, 0.62 gm on the virus inoculated plants
compared to 2.13gm on non-inoculated ones. It has been found that the
Rhizobia induced significant increase in nitrogen percentage at p=0.05 in the
foliage, 1.29% in plants non-treated with Rhizobia non-inoculated by the virus
compared with 2.502% in Rhizobia treated-virus inoculated plants and 2.550%
in Rhizobia treated non inoculated plants. The virus caused an increase in
nitrogen percentage, 1.877% compared to 1.29% in non-inoculated plants. The
Rhizobia caused an increase in pods number\plant, seed number\plant, and seed
dry weight (gm)\plant, 25.6, 114, 32.4 compared to 12.8, 70.6, 8.7 in non-treated
plants respectively. The treatment of virus inoculated plant by Rhizobia
induced a significant increase in these values, except with nitrogen percentage
in seeds, 16.4, 84.6, 10.4, 4.3 respectively.
