عنوان مقاله [English]
To date, Calendula Officinalis L. applications have been expanded as a decorative and medical plant, in horticulture, green spaces, pharmaceuticals, and cosmetics industry. Calendula officinalis L. can be broadly applicable as an antiseptic and anti-inflammatory as well as a light antibacterial and antiviral agent. Being native to Mediterranean countries, water requirement and crop coefficient (Kc) pertaining to Calendula officinalis L. in arid regions need more evaluations. To know about the water requirement of crops is necessary to manage agricultural water and irrigation scheduling in hydrological studies and field management. This is closely related to the exact estimation of crop evapotranspiration (ETc) which depends on crop characteristics, development stage, weather parameters, environmental status, and management practices.
Miranda et al. (2006) used weighing lysimeter for measuring tabasco pepper daily evapotranspiration and crop coefficient. Their results showed total ETc observed during the 300-day crop season was 888 mm, with maximum daily value of 5.6 mmd-1. Ghamarnia et al. (2014) used drainage lysimeters to estimate Kc of black cumin in semi-arid regions of Iran. In their research, the black cumin water requirement of 724 mm was estimated using water balance method. Bakhtiari et al. (2011) recorded hourly data from Grass reference evapotranspiration in three periods in a year using lysimeter in the semi-arid climate of Kerman Province. Lysimetric data can be used to estimate six grass evapotranspiration models, including; FAO-56 Penman–Monteith, Penman-Kimberly 1996, FAO-24 Blaney-Criddle, FAO-24 Radiation, Makkink, and Hargreaves-Samani. In all three periods, the Makkink method indicated poor performance; hence, it cannot be recommended for this region.
Crop coefficients were calculated for many plants except medicinal plants during the growing season. The results were reported by FAO in the table below. According to the studies mentioned above, the crop coefficient and crop evapotranspiration were calculated for medical plants. In Iran, due to the great use of medicinal plants as a food additive or medicine, calculating the crop coefficient and evapotranspiration for medical plants is inevitable. Low rainfall in arid and semi-arid climate regions of Iran, makes it necessary to calculate the evapotranspiration, in order to determine the amount of water required for the cultivation region of medicinal plants.