The effects of treatment with pesticides on some rice yield components were
studied. Results clearly indicated that carbofuran was the most effective on the
weight of grain yieldlhill, weight of 1000 grain, grain yield/fed. and straw yield/hill,
these values were 38.39 gm, 35.23 gm, 4.04 ton and 33.66 gm, respectively.
Diazinon came after carbofuran in their effect on the yield components of rice, the
weight of grain yieldlhill, weight of 1000 grain, grain yield/fed. and straw yieldlhill,
were 36.99 gm, 32.80 gm, 3.85 ton and 30.05 gm, respectively. The herbicide
thiobencarb was not effective on all components of rice yield except the effect on the
weight of grain yieldlhill. The persistence of pesticides in rice fields under flooded
conditions were studied. The residues of carbofuran in the water samples_, were:
0.003, 0.034, 0.052, 0.028 and 0.020 ppm after zero time, one, two, three and four
weeks of treatment, whenever these values in soil samples were: 3.231, 2.511,
1.782, 1.352, 0.971 and 0.850 ppm after zero time, one, two, three, four weeks and
two months, respectively. Diazinon residues also detected in water and soil samples
during the period of experiment, these values ranged from 2.203 ppm at zero time in
the soil sample to 0.0004 ppm after four weeks in the water sample. The residues of
thiobencarb in the rice field water were decreased from zero time 0.8647 ppm to
0.0065 ppm after 4 weeks of treatment, while these residues in the soil samples were
increased from zero time to the second week and then decreased again. The
residues of the tested pesticides were not detected in all samples of rice grain.