Effects of drought stress and nitrogen on yield and some physiological characteristics of Quinoa (Chenopodium quinoa Willd.)

In order to investigate the effects of drought stress and nitrogen on yield, yield components and some physiological characteristics of Quinoa (Santamaria cultivar), a factorial experiment was conducted in a completely randomized design (CRD) in the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran in 2020. Factors including drought stress levels (control, moderate and severe stresses) by increasing the frequency of irrigation and nitrogen (0, 50, 100, 150, 200 and 250 kg ha-1) were from the urea source. The results showed that the highest biomass (42.87 g plant-1) and grain (17.20 g plant-1) yields were in control and 200 kg ha-1 of nitrogen and the lowest in severe stress and 250 kg ha-1 of nitrogen 9.49 and 2.14 g plant-1, respectively. The amount of reduction of grain yield under the moderate stress at nitrogen levels were in the range between 32.9-80.1% and in the severe stress between 73.0-87.9% compared to the control and 200 kg ha-1 nitrogen. Increasing drought stress decreased other traits such as 1000-seed weight, harvest index, plant height, relative water content and superoxide dismutase, but increased peroxidase. Ascending the nitrogen descended the relative water content (up to 100 kg ha-1), peroxidase, superoxide dismutase and catalase. In non-drought stress condition increasing nitrogen went up chlorophyll a, b, carotenoids, soluble proteins, chlorophyll fluorescence and stomatal conductance but went down in drought stress conditions (moderate and severe). The results of this experiment showed that in Quinoa (the Santamaria cv.), the effect of nitrogen depends on the amount of water available and with increasing drought stress decreases the effect of nitrogen.