عنوان مقاله [English]
Background and Objectives: Nowadays herbicides are one of the important input at modern agriculture system. Crop damage due to long lasting herbicide residue, also herbicide drift on neighbor crops are the dangerous consequences of their application on non-target species. Because of soil tillage and environmental conditions just a little amount of applied herbicides are available for plants and the rest of it will lead to limitation for next rotations. So it is important to focus on herbicide residue in agricultural soil and also in agricultural ecosystem and environment safety
The purpose of this experiment was to determine the sensitivity of wheat and barley to pendimethalin residue by using bioassay and find out about the sensitivity of this crops.
Materials and methods: In order to evaluate the soil residue of pendimethalin an experiment based on completely randomized design were carried out at greenhouse of Agricultural Faculty of Gonbad Kavous University. At this experiments different doses of pendimethalin (0, 1, 5, 10, 15, 20, 30, 40, 50, 75 and 100 % of recommended dose) were applied on wheat and barley and finally the dry weight of root and shoot of crops were measured. The concentration of herbicide were made by dilution of stock solvent. Three and four Logarithm logistic curves were used to fit the data. R software 3.3.1 and drc package were used to analyze the data and draw the graphs.
Results: Results indicated that almost all data were followed the three parameter logarithm logistic curve. Results of separate fitness of data showed that always the residue of pendimethalin caused reduction of dry weight of the evaluated crops. Fifty percent reduction of shoot dry weight of wheat and barley were obtained from 400.5 and 623.05 g.a.i.ha-1 of pendimethalin and the ED50 values of root dry weight of wheat and barley were 65.88 and 269.66 g.a.i.ha-1 of pendimethalin respectively.
Discussion: Generally the results of simultaneously fitted data showed that wheat is always more sensitive to pendimethalin rather than barley. Based on results even the very little amount of herbicides can cause damage in crops so considering the sensitive crop in rotation is so important since this residue can stay active even at two season crop and make crop injuries. The selection between 3 and 4 Logarithm logistic model was based on 1. Lack of fit test significance 2. Significance of estimated parameters specially e parameters and the way of distribution of data around the curve (graphical observation).