Water use efficiency and quantitative and qualitative response of quinoa to different concentrations of salicylic acid application under deficit irrigation conditions

The total area under quinoa (Chenopodium quinoa Willd.) cultivation and its grain consumption have increased in recent years because of its nutritional properties and ability to grow under harsh environmental conditions, such as drought. The main goal of this work was to evaluate growth, crop quantitative and qualitative yield, and water use efficiency (WUE), as well as to determine the quinoa response, variety ‘Titicaca’, to different salicylic acid concentrations (SA) (0, 0.5, 1 and 2 mM) under different irrigation levels (100, 75, and 40% field capacity (FC)). The field experiment was conducted in split plots in three blocks during the 2019 growing season, in the research field of Shahid Bahonar University of Kerman, Iran. The results demonstrated that while the plants subjected to deficit irrigation displayed significant reduction in crop growth rate, biological yield, seed yield and its components, the high concentrated SA (2 mM) application led to improving the mentioned traits. Under normal irrigation conditions, moderate concentrations and under severe water deficit, high concentration of SA resulted in improved growth, WUE, and grain protein yield. The highest WUE was achieved by deficit irrigation and high SA concentrations. Water deficit increased grain protein content, while increased SA concentration reduced its content. In contrast, reduced grain protein yield was observed when water deficit occurred while SA application led to improving protein yield. In general, the results showed that considering the water resources accessibility in quinoa fields, different salicylic acid concentrations can be used to improve the water productivity and performance in arid and semi-arid regions.