The estimation of evapotranspiration and crop coefficient of purslane herb plant in Shiraz

Accurate determination of water requirement of plants plays an essential role in determining the dimensions of water facilities, irrigation planning, increasing productivity and irrigation efficiency. The most accurate and standard method of determining the water required by plants is the water balance method using a lysimeter. Purslane as a medicinal plant crops as weeds, special importance has grown in many regions of the world. Purslane many adverse conditions such as drought, salinity and lack of food is consistent. Accordingly, in order to determine crop coefficient (Kc) herb purslane and using three drainage lysimeter during a season in Shiraz. Actual daily evapotranspiration was estimated by water balance equation in lysimeter and potential evapotranspiration with grass plant 12 cm (plant source) was calculated. By dividing the actual evapotranspiration of the plant on potential evapotranspiration, crop coefficient was measured daily during the growing period studied. At the end of the season and at different stages of growth, the values related to portulaca oleracea plant coefficients including initial, developmental, middle and endpoints were 0.9, 1.1, 1.4 and 0.8, respectively. The seasonal water requirement of portulaca oleracea in the study area was 358.97 mm. The average evapotranspiration of the initial, the development, the middle and the final periods were obtained 68, 87.6, 96.11 and 107.24 mm, respectively. The general conclusion of this study is the cultivation of this low water consumption plant in arid and semi-arid regions, including Shiraz.