Delineating the role of host plants in regulating the water and salinity stress induced changes in sandalwood roots.

The interaction of root hemi-parasite (sandalwood) with its hosts is crucial for establishing successful plantations under abiotic stresses. In the present study, we explored the best possible host for sandalwood along with its effect on sandalwood physiology in terms of water and nutrients. Interactive effects of host species (, , , , and ) with sandalwood were observed under eight treatments {100% best available water (BAW); 100% BAW + nutrient medium; 50% water deficit; 50% water deficit + nutrient medium; 100% saline water (EC 8ds/m); 100% saline water (EC 8ds/m) + nutrient medium; 50% water deficit + saline water (EC 8ds/m); and 50% water deficit + saline water (EC 8ds/m) + nutrient medium}. A significant change in morpho-physiological traits of sandalwood roots was observed under different stress conditions, which were slightly improved through external supply of nutrient medium. (Shisham) and (Dek) seemed to be the best host plants providing better environment for sandalwood growth and development, i.e., higher plant height (59.7 and 53.68 cm) and collar diameter (3.24 and 3.07 mm) under stresses by maintaining water and ionic balance. Root length is an important parameter that was reduced by 27.58%, 19.22%, and 36.3% under water deficit, salinity, and combined stress of water deficit and salinity. Sandalwood grown with and maintained the lowest w (- 1.38 MPa) and s (- 1.47 and - 1.48 MPa), respectively. In addition, sandalwood cultivated with and had higher accumulation of soluble proteins (0.48 and 0.42 mg/g) and soluble sugars (98.56 and 91.04 mg/g) in their roots. Results also showed that sandalwood roots had higher K/Na with compatible host, i.e., with (1.85) and (1.83) than other studied hosts. It was also observed that sandalwood plants could not grow and survive alone under stress conditions even with application of nutrient medium. Based on the morphological traits, it was observed that sandalwood grown with hosts, and was able to tolerate stress conditions better than other studied hosts. We can further recommend growing sandalwood with and as a viable option to endure adverse environmental conditions.