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Articles by N.N. Malik
Total Records ( 3 ) for N.N. Malik
  A. Lodhi , N.N. Malik and F. Azam
  A greenhouse experiment was conducted to study the uptake and metabolism in cotton leaves of 14C-labelled cyfluthrin, (C22H18Cl2FNO3, active ingredient of Baythroid insecticide). The labelled chemical was sprayed onto the selected portions of leaves which were subsequently studied for the movement (using autoradiography) and recovery of 14C (using extraction, purification procedures). Autoradiography showed a fairly rapid movement of 14C in the leaf tissues through vascular tissues. Movement was more efficient when application was made on the mid-rib region. Dissipation of 14C was also fast and even after 2 days, >60 percent of it was unaccounted. Subsequently, however, the losses were slow and amounted to 70.6 percent after 35 days. Thin layer chromatography/co-chromatography of organic extracts followed by linear scanning revealed that >60 percent of the 14C was still present as parent compound. Partial hydrolysis of cyfluthrin was found to be the main process involved in degradation that resulted in two major degradation products or metabolites.
  A. Lodhi , N.N. Malik , T. Mahmood and F. Azam
  Laboratory incubation experiments were conducted to study the response of bacterial and fungal population, soil microbial biomass, urease, amylase, invertase and cellulase to Baythroid applied at 0, 0.4, 0.8, 1.6, 3.2 and 6.4 pg g–1 soil (on an active ingredient basis). Generally, a positive effect on bacterial and fungal population was observed. 'Bacterial population increased from 13 to an average of 25 after 5 days of incubation of soil samples treated with different levels of Baythroid. Baythroid did not have a significant effect on fungal population, which was quite low after 5 days of incubation. After 15 days of incubation, however, Baythroid caused a substantial increase in fungal population although no consistent trends were observed with the rate of application.
Carbon dioxide evolution from soil was almost unaffected by Baythroid except at the lowest and the highest levels of addition, where a negative and a positive effect, respectively, was obvious. Cumulative losses of CO2-C increased by 38% at the highest level of Baythroid. The microbial biomass C varied between 138 and 147 pg CO2-C g–1 soil in differently treated soils, a substantially positive effect of Baythroid was observed only at the highest rate of addition, while at lower levels a positive but non-significant effect was observed. Amylase activity increased by a maximum of 91.5% at Baythroid level of 1.6 μg g–1. At 6.4 μg g–1 soil Baythroid, however, the activity was reduced by 47.9%. Invertase activity also increased by 110.9% at 1.6 μg Baythroid g–1 soil followed by a decrease of 40.3% at the highest level tested. Cellulase activity was not much affected, although an increase of 18.5% was observed at 1.6 pg g–1 soil Baythroid. At the highest level of Baythroid, however, cellulase activity was reduced by 25.9%. Response of urease was almost similar to that of other enzymes. However, maximum increase of 40.9% was achieved at 0.8 pg g–1 soil Baythroid, while the decrease (9.1%) at higher levels of Baythroid was less pronounced as compared to that for other enzymes. All the four enzymes showed a positive relationship in their response to different rates of Baythroid.
  A. Lodhi , N.N. Malik and F. Azam
  A field lysimeter experiment was conducted to study the uptake by plants, dissipation and movement in soil of 14C-cyfluthrin (active ingredient of Baythroid, an insecticide produced by Bayer, Germany). Cotton and wheat plants were grown in succession to study the uptake of 14C. The chemical was worked well into the soil supporting the growth of a healthy cotton plant. The plant harvested at maturity contained 0.376 percent of the applied 14C; a major portion (ca 65 percent of the total) of the 14C being located in the stem portion. Wheat plants grown after cotton contained 0.11 percent of the initially applied 14C.
Dissipation of 14C from the soil-plant system was fairly rapid and after 9 weeks (during growth of cotton), ca 50 percent of the applied 14C was unaccounted. Subsequent losses were slower and during the remaining study period of 29 weeks, a further decrease of only 10 percent of the applied 14C occurred. Wheat growth and organic amendment caused a decrease in the loss of 14C from the soil-plant system. At all sampling intervals, a greater proportion of 14C was restricted to the top 0-10 cm layer and the amount consistently decreased with depth. In general, >80 percent of the 14C determined in soil at different sampling intervals was present in forms non-extractable with methanol.
 
 
 
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