Abstract :
Study of soil bacteria and growth behavioral response of rice paddy treated with Agro herbicides in two seasons in Abakaliki
L.G.A. was investigated using standard Microbiological procedures. The results obtained from Bacteria enumeration showed
that soil samples from treated rice paddy analyzed during dry season had aerobic plate count ranging from 3.2 x 109
cfu/g to 9.5
x 109
cfu/g for treated soil samples and 9.2 x 109
to 1.04 x 1010 cfu/g for the controls. The result of aerobic plate count from soil
samples simulated with Butachlor and Bispyribac-sodium at varying concentrations during rainy season showed lower colony
counts on 7 days of application and higher colony counts on 55 days of application. Moreover, result of aerobic plate count
obtained from soil samples simulated with mixture of Butachlor and Bispyribac-sodium at varying concentrations had lowest
colony count of 5 x 108
cfu/g at 3.13ml/333.3ml concentration on 7days and highest colony count of 4.1 x 109
cfu/g at same
concentration on 55days after applications. The control samples showed colony counts within the ranges of 8.3 x 109
cfu/g to 8.9
x 109
cfu/g. There is no significant difference between bacteria load of treated and untreated soil samples during dry and rainy
seasons at p > 0.05. The results of isolation and identification revealed that six and five bacteria were isolated from treated soil
samples during dry and rainy seasons respectively. Nine bacteria were also isolated from control soil samples studied. The
bacterial isolates are of the genera: Bacillus, Pseudomonus, Escherichia, Rhizobium, Azotobacter, Enterobacter, Proteus,
Micrococcus, and Staphylococcus. Finally, the result of growth behavioral response of treated rice paddy showed delayed
growth 15 days after application in most cases except PRE 3 that extended to 30 days while there were gradual increase in the
rice growth with highest growth rates observed 55 days after application. This growth increase could be as a result of
degradation of hydrocarbon component of agroherbicides used and soil enrichment by beneficial bacterial isolates initially
affected by the agroherbicides.
Keyword :
Soil Bacteria, Growth Behavior, Rice Paddy, Agro Herbicides and Abakaliki