Estimation of water requirement and crop coefficients of Calendula officinalis L. in a semi-arid climate

Calendula officinalis L is a medicinal plant used for manufacturing skin and beauty medication product. Estimating Calendula officinalis water requirement, crop evapotranspiration (ETc) and crop coefficient (Kc) are among the areas which indeed require more research. The study was conducted to calculate Calendula officinalis L. crop coefficients (Kc) and crop evapotranspiration (ETc) because the semi-arid regions face with water scarcity problem; in which management of water resources is vital. This study is performed in Kerman, a city in southeastern Iran with semi-arid climate. In order to estimate the crop evapotranspiration, six lysimeters has been used. The Calendula officinalis were grown in five lysimeters, and the grass reference crop was grown in a lysimeter. Moreover reference evapotranspiration (ETo) has been calculated by Penman-Monteith method, and was compared to ETo obtained from lysimeter. In this study estimated Calendula officinalis crop coefficients in different growth stages were 0.71, 1.28, 1.5 and 0.66, respectively. The Calendula officinalis water requirement for the result obtained from lysimeter was 320.6 mm, also the reference water requirement obtained from lysimeter and Penman-Monteith method was 309.1 mm and 270.1 mm.