Optimizing chickpea (Cicer arietinum L.) and dragon’s head (Lallemantia iberica) intercropping in a semi-arid region

In regions with arid and semi-arid climates, water deficiency stress severely impacts plant growth, morphology, physiology, and yield. Addressing these challenges requires innovative agricultural strategies, such as increasing biodiversity and adopting drought-resistant crops like chickpea ( Cicer arietinum L. ) and dragon’s head ( Lallemantia iberica ). However, the competitive dynamics between these crops under varying soil moisture and temperature conditions remain poorly understood. This study aimed to optimize resource use efficiency in a chickpea– L. iberica intercropping system (Ic; 50 % chickpea + 50 % L. iberica ) under different irrigation regimes and sowing dates. The most sustainable treatment was Ic (I 20 S 1 ), combining conventional irrigation (I 20 ) and autumn sowing (S 1 ), which achieved the highest total water equivalent ratio (WERt = 2.43) and total land output (TLO = 3762.3 kg ha⁻ 1 ). This treatment also recorded the highest nitrogen (N) uptake (4032 mg kg⁻ 1 ) and the greatest concentrations of linolenic acid (LNA = 69.3 %), linoleic acid (LA = 15.6 %), and oil content (31.3 %) in L. iberica . In contrast, Ic (I 40 S 1 ), combining deficit irrigation (I 40 ) and autumn sowing, produced the maximum relative water content (RWC) and water use efficiency (WUE) for chickpea (67.2 and 0.14 kg m⁻ 3 ) and L. iberica (71.1 and 0.065 kg m⁻ 3 ). Furthermore, catalase (CAT) and ascorbate peroxidase (APX) activities, along with total flavonoid content (TFC) in roots, were elevated in intercropping systems, contributing to improved drought tolerance by reducing oxidative stress. Notably, the competitive ratio of chickpea (CRc = 2.11) confirmed its dominance without excessive competition, supporting stable coexistence. These findings suggest that Ic (I 20 S 1 ) and Ic (I 40 S 1 ) treatments enhance the cultivation of L. iberica , offering a sustainable strategy for improving oil yield and optimizing resource utilization in water-limited environments. • Chickpea yield reached 2922.5 kg/ha under Ic (I 20 S 1 ). • WUE peaked at 0.42 kg/m³ in chickpea under Ic (I 20 S 1 ). • L. iberica oil content rose to 31.92 % under Ic (I 20 S 1 ). • TLO increased by 68.4 % in Ic (I 40 S 1 ) vs. sole cropping. • WERt reached 2.43 in Ic (I 20 S 1 ), saving 143 % water.