Deciphering rootstock-driven morphological plasticity & survivability in citrus under progressive water deficit stress

Abstract

Drought stress represents one of the most significant abiotic limitations to citrus growth and survival. Understanding the rootstock-specific morphological responses is crucial for selecting resilient genotypes suitable for water-limited orchards. A controlled pot experiment was conducted during the 2024–2025 period at Banda University of Agriculture and Technology, Banda, Uttar Pradesh. The study involved seven citrus rootstocks, viz., Rangpur Lime, Cleopatra Mandarin, Rough Lemon, Sour Orange, NRCC RS-3, RS-4, and RS-6, subjected to four levels of water stress (control, 0.4 bar, 0.6 bar, and 0.8 bar) over a period of 120 days. Plant mortality increased with greater water deficit stress, reaching 15.42% at 0.8 bar, with Cleopatra Mandarin displaying the highest mortality rate of 23.33%. Compared with the control group, plant height, stem diameter, leaf number, and shoot number declined by 25.78%, 46.64%, 21.8%, and 22.39%, respectively, at 0.8 bar moisture tension. Both Rough Lemon and Rangpur Lime performed better, demonstrating the least reduction in all measured parameters compared to the other rootstocks under severe water deficit stress conditions. In contrast, Cleopatra Mandarin and NRCC RS-4 exhibited the greatest reductions in morphological parameters, indicating lower tolerance to water-deficit stress. Overall, Rough Lemon, Rangpur Lime, and Sour Orange displayed superior drought resilience, characterized by better canopy retention and survivability. These rootstocks are promising candidates for enhancing drought tolerance and maintaining productivity in water-limited citrus orchards.