Influence of host plant selection on salinity tolerance and antioxidative defense in Sandalwood (Santalum album L.)

• Sandalwood’s tolerance to salinity stress is strongly influenced by the choice of host plant. • Salinity boosts antioxidant enzyme activity in sandalwood grown with suitable host. • Melia dubia and Dalbergia sissoo maintained sandalwood growth under salinity stress. • Optimal host plants improve K⁺/Na⁺ ratio and reduce oxidative damage in sandalwood. • Sandalwood shows salinity resilience, offering potential for saline land cultivation. Sandalwood ( Santalum album ) has been cherished in India for centuries; however to date, literature has not extensively explored the physiological and biochemical changes in sandalwood associated with various host plants under salinity stress. Considering the potential for sandalwood, a randomized block design experiment was conducted on sandalwood grown with ten different host plants and irrigated with good quality water (EC iw ∼0.82 dS m -1 ) and saline water (EC iw ∼6 dS m -1 ), ensuring successful root parasitism. Results indicated significant variations in plant height, diameter, biomass, and root length across host species. Among the different host plants studied, Melia dubia, Dalbergia sissoo, and Azadirachta indica improved the plant height (46%), biomass (45%), haustoria number (120%) and diameter (75%) compared to other hosts in saline condition. Physiologically, these hosts enhanced SPAD value (up to 22.55), proline content (by 460%), improved membrane stability with electrolyte leakage as low as 10.85%, maintained K⁺/Na⁺ ratio (>1.0), and exhibited reduced lipid peroxidation (by 10%) and H₂O₂ accumulation. Non-enzymatic antioxidants increased by more than 40%, and antioxidative enzyme activities particularly superoxide dismutase was upregulated by up to 50% under salinity stress, with the highest increase observed in sandalwood grown with M. dubia , indicating enhanced oxidative stress tolerance. Principal component analysis also confirmed that D. sissoo and M. dubia are the most supportive hosts for sandalwood under salinity stress, while Citrus aurantium was the least favourable. Overall, the findings suggested that sandalwood grown with hosts M. dubia and D. sissoo demonstrates their critical role in mitigating salinity stress offering an opportunity to establish sandalwood plantations in saline environments.