تقييم كفاءة بعض العوامل الأحيائية في تحطيم مبيد الأدغال كلايفوسيت في التربة ودراسة أمتزازه بأستعمال السليكا النانوية

Evaluation of the efficiency of some biological agents in the degradation of the weed killer glyphosate in the soil and the study of its adsorption

A laboratory and field experiment was carried out at the College of Agriculture – University of Karbala with the aim of evaluating the biological factors Trichoderma harzianum, Azotobacter chroococcum, Bacillus subtilis, Pseudomonas fluorescens and their role in the biodegradation of the clifosate pesticide under the trade name Teller SL 48%. Laboratory studies included the assessment of tolerance and growth of the factors. Biology in culture media treated with different concentrations of pesticides, field studies included the role of biological factors in biodegradation and measurement of clyphosate weed pesticide residues at concentrations of 10, 15 and 20 ml / liter of water in soil and water using HPLC technology. Nano-silica has also been used as an adsorption agent to remove pesticides from water.
It is noted from the laboratory study of the treatment of agricultural media with concentrations of 10, 15, 20 and 25 ml / liter of clifosate pesticide, that the bacterium chroococcum A. showed a remarkable response in its ability to grow and tolerate the concentrations of the pesticide used, as it recorded a growth rate of 7.20 cm in diameter and did not differ significantly from The treatment of the fungus T. harzianum, which recorded a growth rate of 6.00 cm in diameter, while the lowest growth rate was 4.60 cm for the bacteria P. fluorescens, which differed significantly from other treatments. Concentrations 10 and 15 ml/L were the best form of extension and growth for A. chroococcum, B. subtilis and T. harzianum, recording growths of 9, 8, 7, 5 and 7.5 cm, respectively, compared to the control treatment that achieved 9 cm. While the bacteria P. fluorescens achieved a growth extension of 6 and 4 cm, respectively.

The results of the study of the percentage of inhibition of the bacteria chroococcum A and the fungus T. harzianum showed that the highest percentage of inhibition by the use of clifosate was for the bacteria at the concentration of the pesticide 20 ml / L, with a percentage of 58.30%, and with significant differences from the treatment of the fungus T. harzianum, which recorded a percentage of inhibition of 66.70% at same focus. The concentration of 10 ml / liter recorded the lowest inhibition rates of 18.90 and 55.60% for bacteria and fungi, respectively. In the light of the obtained results, three concentrations were chosen, namely 10, 15 and 20 ml / liter, with the selection of the bacteria chroococcum A and the fungus T. harzianum for field experiments.
The results of the study of fungus and bacteria evaluation of the biodegradation of clifosate in the soil showed that the three concentrations used 10, 15 and 20 ml / liter of water recorded 4238, 6176, 7933 and 4126, 6050 and 7353 mg L-1 for each of the fungus and bacteria treatment respectively after The treatment was directly compared to the control treatment, which recorded 4640, 6828, 8725 mg L-1, then the concentration of the pesticide began to decrease after 3 days of treatment, recording 1552, 2235, 3096 and 1132, 1955, 2626 mg L-1, respectively. On the seventh day, the concentrations decreased, recording 975, 1227, 1970 and 541, 942, 1242 mg L-1, respectively, compared to the control treatment, which recorded 1493, 3675 and 4536 mg L-1. On the tenth day, no residues were recorded in the soil.
The results of the study of estimating the residuals of clifosate in water for a period of 15 days showed that the three concentrations used 10, 15 and 20 ml / liter of water recorded 3520, 5600 and 7955 mg l-1, respectively, immediately after the treatment, then the concentration of the pesticide began to decrease and with the passage of days it was recorded The study until reaching 822, 2011 and 3652 mg L-1 respectively on the seventh day. The concentrations decreased on the tenth day, recording 356, 852, and 1203 mg L-1, respectively, and after that, on the 15th day, the HPLC device was not sensitive to any of the concentrations used in the water treatment.
The results of a study using nano-silica as an adsorption agent in the removal of clifosate in water indicated that the concentration of 200 mg L-1 achieved the highest rate of removal of the pesticide with a percentage of 89.37%, surpassing the other concentrations of 100 and 150 mg L-1, which achieved 63.45 and 82.87%. respectively .