Determination of water requirement, single and dual crop coefficient of garlic (Allium sativum) in the cold semi-arid climate

The purpose of this study was to determine the water requirement, single and dual crop coefficient of garlic using a drainage lysimeter. The lysimeter experiments were conducted during 2008-2009. According to the experimental results, garlic water requirements (ETC) in this period were 546.5 mm and 519.2 mm, respectively, during the growing season. A reference evapotranspiration (ET0) was simulated with artificial neural network (ANN) method during garlic growth season. Results showed that crop coefficient value (K-C) in initial and final stages were 0.53, 1.4 and 0.3, respectively. The results were compared to the single and dual crop coefficients from the FAO-56 procedure. Results showed that maximum differences between ETC of single and dual K-C values were observed at initial and final stages. Also, this study showed that dual crop coefficient is more precise (RMSE=38%) but the advantage of single crop coefficient is simpler for a user.