Assessment of establishment techniques and performance of sandalwood (Santalum album L.) in commercial plantations in semi-arid tropics of India

Sandalwood (Santalum album L.) is highly prized tree spreading across agrarian landscape for its commercial value particularly the sweet fragrant aromatic oil. The tree occurs in varied climate and soil, however, successful establishment of commercial sandalwood plantation is rather difficult mainly due to its non-specific root parasitization, and lack of research information on the performance of field grown sandalwood, mainly planting geometry, and the host species-sandalwood density/row ratio. Therefore, the present investigation on the assessment of production techniques and sandalwood performance under irrigated condition was carried out in the existing farm plantations in Yadagir and Kalaburagi districts of Karnataka in peninsular India having semi-arid climate. Growth and development of sandalwood was superior with multi-species (three) host combination [custard apple (Annona squamosa) + curry leaf (Murraya koenigii) + casuarina (Casuarina equisetifolia)] followed by two-host combination [mango (Mangifera indica) + custard apple],besides mahogany (Swietenia macrophylla) and mango (Mangifera indica) as single hosts in that order, while performance was not adequate with jamun (Syzygium cumini) and red sander (Pterocarpus santalinus) while was moderate with guava (Psidium guajava) and sapota (Manilkara zapota). Among the planting geometries, superior growth of sandalwood occurred with 6.0 × 6.0 m geometry for host species and sandalwood both in separate alternative rows followed by 4.0 × 4.0 m and 6.0 × 2.0 m geometries, while the growth was poor with 6.0 × 6.0 m (hosts species (H) to H); 6.0 × 3.0 m (sandalwood (S) to S) followed by 3.0 × 3.0 m and 2.5 × 2.5 m planting geometries for both host species and sandalwood. Similarly, superior performance of sandalwood occurred with H:S ratio of 1:1 as against 1:2, and when sandalwood was planted at 3.0 m away from the host plant followed by 2.0 m. Thus, for commercial plantation it is advised to include multiple hosts species (two or more) with a spacing of 6.0 × 6.0 m for both H to H and S to S, keeping sandalwood tree at 3.0 m distance from the host with an overall population 554 trees ha⁻¹ comprising 277 plants each of host species and sandalwood in the semi-arid region of peninsular India. Further, square planting with alternative rows of sandalwood followed by hosts or zig-zag planting with sandalwood in between hosts in separate alternate lines could be adopted advantageously, and whenever two or more host species mix is used one of the hosts must be of long rotation for instance mango with other commercial crops of short rotation as found in the present study.