Mitigating water stress in Medicago sativa L. through irrigation system modification: a field study in a semi-arid...

In arid and semi-arid regions, severe water scarcity critically threatens agricultural sustainability and food security. Enhancing crop resilience and water productivity is therefore an urgent priority. This study addresses this imperative by evaluating advanced irrigation strategies for alfalfa (Medicago sativa), a vital forage crop, to optimize yield and quality under water-limited conditions. This study evaluated irrigation strategies to enhance water use efficiency (WUE) and resilience in alfalfa. A two-year field experiment in Jiroft, Iran, compared three irrigation systems-Flooding Irrigation (FI), Subsurface Drip-Tape Irrigation (SDTI), and Subsurface Drip Pipe Irrigation (SDPI)-under four irrigation levels (100%, 90%, 80%, and 70% of crop water requirement). Results showed that the SDPI system achieved the highest water use efficiency (WUED and WUEF). However, maximum dry and fresh forage yields (DFY, FFY) were obtained with FI at full irrigation (100%). Under irrigation levels (70%), SDPI improved forage quality by increasing CP, soluble carbohydrates, proline, and antioxidant enzyme activity, while reducing fiber content. Irrigation at 70% generally enhanced WUE and these biochemical indicators across all systems. The findings demonstrate that the SDPI system, particularly under irrigation levels (70% requirement), effectively improves the nutritional value and water productivity of alfalfa, supporting its adoption for sustainable production in water-limited environments.