Evaluation of irrigation management on yield, yield components, and water use efficiency of Quinoa (c.v. Giza-1)

Global climate change is expected to cause increased temperatures and more unevenly distributed precipitation, resulting in severe drought, heatwave, and soil salinity in arid and semi-arid areas [4,5]. Also, poor irrigation management not only decreases water use efficiency but also the drought intensity. It is estimated that 30% of the global land surface will experience extreme drought by the 2090s [1]. Drought stress is the most serious abiotic stress that has a direct impact on crop performance [2]. Introducing new crops that are adapted to environmental stresses is one of the most effective methods for sustainable crop production and food security in arid regions [3]. Quinoa (Chenopodium quinoa Willd.), traditionally called the mother of grains, has the potential to grow under drought, tolerating levels as stresses in other crop species. Drought conditions are key abiotic factors affecting quinoa’s growth and development. However, to the best of our knowledge, no information is available about irrigation with partial root-zone drying management on quinoa. Therefore, the present study in greenhouses conditions was conducted to study the effect of irrigation management on the morphological and grain yield of quinoa. The finding would be useful to enhance food security in the context of global climate change. This research aimed to examine the effect of deficit irrigation and partial root-zone drying on morphophysiological properties and grain yield of quinoa (c.v. Giza-1) in Ferdowsi university of Mashhad during 2019 (winter-summer). Research Station is located in north-east Iran at 36° 16' N latitude and 59° 36' E longitude and its height from sea level is 958 meters. The seeds of Quinoa were planted at a depth of 1.5 centimeters in the loamy soil of each pot and were irrigated with tap water. The experiment was a completely randomized design (CRD) with three replications under pot planting conditions, four irrigation regimes (full irrigation-FI, deficit irrigation-DI, alternate partial root-zone drying-APRD, and fixed partial root-zone drying-FPRD). In the APRD and FPRD regimes, pots were separated into two sections equally in the vertical direction, and irrigation was supplied to one section each time and then switched to the drier sections (APRD), but in the FPRD regime, one section all during a time of growth was dried and irrigated. In limited irrigation treatments, 50% water of FI was applied either to the filed capacity in the pot in DI or to one side of the pot alternating in APRD, and to one side of the pot fixing in FPRD, respectively. At harvest, plant height, leaf number, and root length were measured. Shoot and root biomass was collected and determined after oven drying at 70oC until constant weight. Grains were collected and measured for yield/plant. The obtained data analyzed using statistical software of SAS (Ver. 9.4) and the means were compared using LSD test at 5 % percent levels. Results showed that irrigation strategies were statistically significant on leaf number, plant height, shoot and root biomass, and grain yield at 1% level and significant on root length at 5% levels. Results showed that the highest plant height and root length (89.7 and 15.3 cm) were in FI treatment and the shortest plant height (58.7 cm) and root length (11.4 cm) were in DI and FPRD treatment. The highest and the least Shoot and root biomass and grain yield were measured in FI (7.9, 1.53, and 15.5 g per plant) and DI (3.5 g per plant), FPRD (0.89 g per plant), and DI (10.2 g per plant) treatments, respectively. With 50 % reduction of water in APRD, FPRD, and DI compared to FI treatment, plant height was decreased by 13.8, 26.8, and 34.6 percent, respectively. Grain yield was decreased by 13.5, 27.4, and 33.3% in APRD, FPRD, and DI compared to FI treatment. From results, it can be concluded that quinoa plant growth is favored by APRD is an effective irrigation strategy to increase grain yield in drought-prone areas. Overall, APRD might be a wise approach for sustaining crop productivity in drought-stressed areas of the world to ensure food security.