Effect of Different Irrigation Regimes on the Nutritional Quality of Surface and Subsurface Drip-Irrigated Amaranth Under Mediterranean Climatic Conditions

This research was conducted with the objective of evaluating the nutritional value of amaranth irrigated with surface drip (SD) and subsurface drip (SSD) systems under Mediterranean climatic conditions in 2019 and 2020. The treatments consisted of regulated deficit irrigation (RDI), conventional deficit irrigation (DI 25 , DI 50 , DI 75 ), full irrigation (FI), and non-irrigated treatment (rainfed, RF) under SD and SSD. The highest protein content was obtained from RF at 13.82% and the lowest protein content was obtained with FI in SD strategies. Oil and oil components were affected by irrigation treatments. Irrigation treatments differed significantly with regards to ash (%), Fe (ppm), and Zn (ppm) in the second year. The content of Ca (%) was not affected by drip system in either experimental year. Proline level increased with increasing water scarcity. The highest amounts of proline were observed in the second year of research in the RF treatment. The highest proline content was observed in the RF treatment (22.20 µmol g −1 ). Oleic acid and the oleic to linoleic acid (O/L) ratio were affected by drip system and treatment. According to multivariate analysis, the effect of irrigation treatments on amaranth quality characteristics were the same under both irrigation systems (SD and SSD). In the Mediterranean region, amaranth is an important plant that can be grown without irrigation.