Determination of evapotranspiration, crop coefficient and growth stages of canola by lysimetric data

Because of the importance of canola as a major oil plant and its compatibility with different climatic conditions, an experiment was conducted in the Agricultural Research Station of Tabriz University to determine its lysimetric evapotranspiration. Lysimetric evapotranspiration was measured 583.6 mm in the study region. Results showed that there was 23.36 percent difference between lysimetric evapotranspiration and potential evapotranspiration resulting from FAO Penman-Monteith method. A relationship for crop coefficient was obtained based on the days after planting and radiation absorbed by plants and was corrected with temperature and leaf area index. The durations of growing stages of spring Canola including initial, development, middle and end stages based on percentage of land cover and LAI were obtained equal to 25, 35, 20 and 20 days, respectively. Also the mean values of crop coefficients were determined for the initial, middle and the end stages of growth equal to 0.72, 1.45 and 0.66, respectively. There was significant difference between crop coefficients resulting from this study with the recommended values in the FAO 56. In this study, changes in the ground cover percentage, LAI, plant height and evapotranspiration were investigated on different days after planting.