Assessment of growth, seed yield, and water productivity of two Chenopodium quinoa cultivars under different irrigation levels in semiarid conditions

Drought management requires information on water productivity, crop water consumption, and relevant crop cultivars. Water productivity is important in determining the relationship between crop yield and evapotranspiration, especially in areas with limited irrigation and low rainfall. During the experiment, the seed yield, yield components, and water-yield relationships of two quinoa (Chenopodium quinoa Willd.) cultivars 'Titicaca' and 'Carmen' under conditions of decreasing irrigation water were determined. It was conducted as a field experiment in three replications and two years (2018-2019). In the experiment, four different irrigation water treatments: I100 - full irrigation (control), I75 - 25% deficit, I50 - 50% deficit, and I0 - 100% deficit (no irrigation), were used. According to the average of two-year experimental data, the seed yield, plant height, 1000-grain weight, and harvest index were 2754 kg ha-1, 75.4 cm, 2.81 g, and 37.7% for the 'Carmen' and 3335 kg ha-1, 108.3 cm, 2.93 g, and 40.5% for the 'Titicaca', respectively. Yield component values decreased due to irrigation water restriction for both cultivars. The water productivity value was similar in the I100 and I75 treatments of both cultivars. The yield response factor (ky) for 'Carmen' and 'Titicaca' was determined to be 1.37 and 1.39 in 2018, and 1.23 and 1.20 in 2019, respectively. At the end of the experiment, it was determined that irrigation had an increasing effect on the seed yield, plant height, 1000-grain weight, and harvest index values in quinoa plants under semiarid conditions. In addition, recommendations were made for the use of the I75 irrigation, which saves water, and for the 'Titicaca', which is more suitable for the climate of semi-arid region.