Investigating the effect of periodic water deficit stress on quinoa plant yield and determining the quinoa water-yield function in a saline soil (case study -Khuzestan province)

The aim of this study was to determine the quinoa water-yield function by applying water deficit stress in different growth stages. This study was performed on quinoa cultivar Titicaca in Ahvaz city in 2019 in a randomized complete block design with 13 treatments and three replications. Treatments including full irrigation and application of three levels of water deficit stress at four different stages of plant growth. The functions of water - quinoa seed yield and water use efficiency were fitted as a quadratic function. The trend of yield increase per water consumption up to 3200 m3 ha-1 was upward. From 3200 to 4000 m3 ha-1 of water consumption, the yield was almost constant and maximum (3650 kg ha-1). The most water use efficiency (1.22 kg m-3) was achieved with water consumption of about 2400 m3 ha-1. From 2400 to 3000 m3 ha-1 of water consumption, the water use efficiency was 1.12 kg m-3. Therefore, more water consumption decreased the water use efficiency. Although water scarcity stress increased the water use efficiency in quinoa cultivation, in order to achieve proper efficiency in deficit irrigation management, in addition to the amount of water consumption, the plant growth stage should also be considered. In the climatic conditions of Khuzestan province, initial and middle stages were the most sensitive growth stages of quinoa to water deficit stress