One strain of microorganisms was isolated from soil previously treated with pendimethalin using enrichment technique and identified using 16S rDNA as Pseudomonas putida (E15). The effect of pH and temperature on the growth ability of the tested strain was investigated. The results show that the optimum pH and temperature for the growth of pendimethalin dissipating strain were 7 and 30°C, respectively. P. putida was used to dissipate pendimethalin from mineral liquid medium with half-live of 5.46 days. Pendimethalin half-live was 51.9 days in untreated mineral liquid medium. P. putida and compost were also evaluated for detoxification of pendimethalin in clay soil. P. putida and compost were effective in pendimethalin dissipation in soil with half-live of 4.67 and 5 days, respectively. Pendimethalin half-live was 62.43 days in untreated soil. Pendimethalin treatment affected analysis of the microbial population growing in P. putida or compost treating soil leachates showed an overall increase in the population of microorganisms. There is no toxicity of pendimethalin detected in soil on cucumber plants after treatment with P. putida or compost. Pendimethalin significantly decreased germination and increased cucumber seedlings mortality rate. P. putida and compost treatments increased the growth parameters. Moreover, no significant difference was observed in the most growth parameters between P. putida and compost treatments. Abnormal development of xylem tissue was observed in pendimethalin contaminated soil as a result of phytotoxicity. The results suggest that bioremediation by P. putida and compost was considered to be effective method for detoxification of pendimethalin in soil.

Identification and mechanism of Echinochloa crus-galli (L.) resistance to fenoxaprop-p-ethyl via physiological and anatomical differences between susceptible and resistant were investigated. The physiological and anatomical differences that were take into account were growth reduction, chlorophyll content reduction, lamina thickness, and xylem vessel diameter in both susceptible and resistant biotypes of E. crus-galli. The results showed that the growth reduction fifty (GR50) of resistant biotype was 12.07-times higher than that of the susceptible biotype of E. crus-galli treated with fenoxaprop-p-ethyl. The chlorophyll content was highly reduced in the susceptible biotype relative to the resistant one of E. crus-galli treated with fenoxaprop-p-ethyl. An anatomical test showed significant differences in the cytology of susceptible and resistant biotypes of E. crus-galli treated with fenoxaprop-p-ethyl with respect to lamina thickness and xylem vessel diameter. The resistance of E. crus-galli to fenoxaprop-p-ethyl may be due to the faster metabolism of fenoxaprop-p-ethyl below the physiologically active concentration or the insensitivity of its target enzyme (Acetyl-CoA carboxylase).

Identification and mechanism of Echinochloa colonum (L.) resistance to bispyribac-soduim via physiological and anatomical differences between susceptible and resistant biotypes was investigated. The physiological and anatomical differences that were take into account were growth reduction, chlorophyll content reduction, protein analysis, lamina thickness and xylem vessel diameter in both susceptible and resistant biotypes of E. colonum. The results showed the growth reduction fifty (GR 50 ) of resistant biotype was 10.2 times higher than that of the susceptible biotype E. colonum treated with bispyribac-soduim. The chlorophyll content was highly reduced in the susceptible biotype relative to the resistant one of E. colonum treated with bispyribac-soduim. An anatomical test showed significant differences in the cytology of susceptible and resistant biotypes of E. colonum treated with bispyribac-soduim with respect to lamina thickness and xylem vessel diameter. Furthermore, leaf protein analysis showed significant differences between the susceptible and resistant biotypes of E. colonum in the number and the density of protein bands. The resistance of E. colonum to bispyribac-soduim may be due to the faster metabolism of bispyribac-soduim below the physiologically active concentration or the insensitivity of its target enzyme, (acetolactate synthase). These results implied the occurrence of E. colonum resistance to bispyribacsoduim in Egypt and provide conclusive evidence that a single resistance mechanism alone cannot explain insensitivity in E. colonum to bispyribac-soduim.

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The objectives of this investigation were to study the effect of herbicide bispyribac-sodium at rate of 16 g a.i/fed on Oryza sativ (L.) cv. Sakha 104, Echinochloa crus-galli (L.) and Echinochloa colonum (L.) grown under Egyptian ecosystem (Nile delta ecosystem). Morpho-physiological changes were take into account were growth reduction, chlorophyll pigment content reduction and reduction of some anatomical leaf parameters in O. sativa, E. crus-galli and E. colonum treated with tested herbicide. Moreover, increasing in membrane integrity (permeability) and leaf water deficit and reducing in leaf water contents were obtained in all tested plants treated with bispyribac-sodium. Ultrastructural changes in tested plants after bispyribac-sodium foliar application were noticed as cytotoxic features (programmed cell death). Cytotoxic features were take into account were mesophyll cell plasmolysis, irregular, granular nucleus, reduction in thylakoid membranes in treated plants compared with untreated plants. The obtained results will improve our understanding to tested herbicide mode of action, which may be overcome or reduce the side effects on non-target plant (O. sativa).

Cytological changes in rice Oriza sativa (L.) cv. Sakha 104, and two different rice weeds i.e. Echinochloa colonum (L.) and Echinochoa crus-galli (L.) after foliar application with fenoxaprop-P-ethyl at rate of 26.25 g a.i /fed. and penoxsulam at rate of 10 g a.i/fed. were investigated. Mesophyll cell plasmolysis and unevenly thickened cell walls were showed in O. sativa after foliar application with fenoxaprop-P-ethyl. Mitochondria multi-fission and increasing in mitochondria number per cell were found in rice and E. crusgalli mesophyll cells. Thylakoid membrane reduction and plastoglubule were noticed in chloroplast of mesophyll cells in E. colonum were recorded. Furthermore, re-growth of E. crus-galli and E. colonum occurred after foliar application with fenoxaprop-P-ethyl. These findings will improve our understanding for the tested herbicides mode of action in wanted and unwanted plants at ultrastructural levels.

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