Biochemical changes in wheat plants as affected by residues of dimethoate and pirimicarb

Abstract

Wheat plants were grown in field plots of 3×3m area. After growth period of two months, the growing plants were sprayed with dimethoate and pirimicarb at the recommended dose. Spraying was repeated after a further 45 days. Plant samples were taken at intervals of zero, three, six, nine, 12 and 15 days after each application. A gradual and continuous degradation of the applied pesticides had taken place in the treated wheat shoots up to the end of the experiment. However, dimethoate showed more residues and persistence rather than pirimicarb. The break down and metabolism of the applied pesticides was correlated with some biochemical changes in the sprayed plants. Sampling dates of three and six days after application were the most critical periods to affect plant metabolism. A decline was noticed in chlorophyll, sugars and carbohydrates, total proteins and RNA content of wheat shoots as a function of the applied pesticides. Free amino acids were accumulated in the sprayed plants, meanwhile the DNA content did not show observable changes as a consequence of the applied pesticides treatment.