Determination of Quinoa (Chenopodium quinoa Willd.) crop coefficient and water requirement in lysimetric condition

The water and soil resources are limited, and the optimal use of water resources in the agriculture needs the most accurate determination of the amount of crop water requirement and crop coefficients in different stages of growth. Quinoa (Chenopodium quinoa Willd.) is one of the plants that has outstanding economic and agronomic characteristics in the production of oil and protein among the sorghums. The present research was conducted to determine the maximum allowable depletion, crop coefficient and water requirement of quinoa under controlled conditions (lysimeter) in two spring and autumn cropping season. The results showed that with a decrease in the moisture level at the beginning of irrigation from 0.4 to 0.2 total available water, the amount of biomass and seed yield had a significant decrease of 24 and 37% in spring cropping and 34 and 47% in autumn cropping, respectively. But the decrease in moisture levels from 0.8 to 0.6 and 0.6 to 0.4 did not cause a significant decrease in seed yield and biomass in both spring and winter cropping. Based on the results, Maximum Allowable Depletion (MAD) was estimated to be 0.6 in both cropping seasons. Overall, the crop coefficient of quinoa (Titicaca variety) in spring cropping was equal to be 0.42 at the beginning of the growing season, 0.95 in the middle of the growing season, and 0.33 at the end of the growing season. In the autumn cropping, the crop coefficient of quinoa was equal to be 0.36 at the beginning of the growing season, 1.09 in the middle of the season, and 0.56 at the end of the growing season.The net water requirement of different treatments varied between 618.1 to 295.5 mm in spring cropping season and between 597.8 to 334.8 mm in autumn cropping season.