Investigation the Effects of Conjunctive Irrigation with Saline Water on Morphological Properties and Yield of Quinoa

Introduction: Increasing population growth along with the lack of freshwater resources have necessitated the use of unconventional water resources in agriculture, as the largest fresh water consumer, especially in the arid and semiarid areas. Application of suitable irrigation management with saline water can reduce the yield loss caused by salinity. Saline farming is based on the cultivation of crops and plant varieties that can tolerate high levels of salinity. Quinoa (Chenopodium quinoa Wild.) is a genetically diverse Andean grain crop that has earned special attention worldwide due to its nutritional and health benefits and its ability to adapt to contrasting environments, including nutrient-poor and saline soils and drought stressed marginal agro-ecosystems. Drought and salinity are the abiotic stresses most studied in quinoa. Cultivation of salinity resistant cultivars, such as Quinoa plant is one of the techniques to use saline water. The results of Jamali and Ansari (2019) showed that irrigation with saline water during all the growth stages of quinoa plants (Titicaca cv) significantly decreases grain yield and 1000 kernel weights by 20.8% and 20.0 %, respectively. Therefore, this study aims to investigate the impact of conjunctive moderation of saline water in irrigation of Quinoa plants (Chenopodium quinoa Wild.). Materials and Methods: Research station is located in northeast of Iran at 36° 16' N latitude and 59° 38' E longitude with 958.0 meters height from sea level. In this study, six irrigation treatments including well water (1.23 dS.m-1; control treatment (W)), saline water (15 dS.m-1, SW), alternative saline water and freshwater (ASW), mixture of 50:50 saline and freshwater (7.2 dS.m-1, MSW), fixed partial root-zone salinity-stress (FPRS), and alternative partial root-zone salinity-stress (APRS) were evaluated on some growth parameters, yield, and physical productivity of water in Quinoa (CV. Titicaca) production. The research was done based on completely randomized design, including three replications as pot planting in the Ferdowsi University of Mashhad, at greenhouse conditions, during 2018-2019. The seeds of Quinoa were planted at a depth of 1.5 centimeter in silty clay soil of each pot and were irrigated with well water. Physical and chemical properties of irrigation water and soil were determined before experiment. The collected data analyzed using statistical software of SAS (Ver. 9.0) and the means were compared using LSD test at 5 % probability. Results and Discussion: The results showed that, different irrigation moderation had a significant impact on physical productivity of water, harvest index, panicle length, plant height, stem diameter, panicle weight, and grain yield at 1% (p < 0.01), but this treatment was significant at 5% (p < 0.05) on branches number, panicle width, panicle number, and 1000 kernel weights. The maximum reduction in physical productivity of water was observed in plants receiving SW treatment (15 dS.m-1 NaCl). Notable increases of 23.1%, 19.2%, 3.8%, and 19.2% in the 1000 kernel weight, 25%, 23.4%, 2.7%, and 18.9% grain yield and 25%, 12.5%, 3.8%, and 25% physical water productivity in Quinoa (c.v. NSRCQ) production were observed when plants were grown under applying ASW, MSW, FPRS, and APRS moderation, compared with SW moderation. Conclusions: Whilst comparing with control treatments (W), the lowest decreases of 19.4%, 23.5%, and 23.1% were noted respectively in grain yield, 1000 kernel weights, and physical water productivity exposed to ASW treatment. The NSRCQ cultivar showed the highest potential for yield and growing under saline conditions (ASW and APRS moderation). Morphological and yield responses of Quinoa (c.v. NSRCQ) to all treatments (moderation saline water), under greenhouse conditions, showed that quinoa has wide plasticity and tolerance to salinity stress. Due to the lack of water resources and increasing population growth, it is recommended to use unconventional water (for exp. saline water) and cultivation of crop varieties (for exp. Quinoa) that can tolerate high levels of salinity, especially in the arid and semiarid areas.