Anatomy and Functional Status of Haustoria in Field Grown Sandalwood Tree (<i>Santalum album</i> L.)

Abstract

A study on the physiology of root parasitism in sandal ( Santalum album L.) was conducted by comparing a six-year-old sandal grown alone and along with a host ( Casuarina equisetifolia ). Although maximum haustorial connections were observed when grown along with the host, sandal formed haustorial connections with plants including grass up to a distance of 3 m. Anatomical studies on haustoria indicated a vascular connectivity between the host and sandal. While the haustoria functioned as a physiological unit supporting nutritional requirements of sandal, direct lumen-lumen xylem connections between sandal and host were absent. Functional status of the haustorial connection was studied by radio-labelling the host ( Casuarina ) and nearby grass with phosphorus ( 32 P). Presence of translocated 32 P in sandal was noticed after six hours of labelling the host. 32 P activity was noticed from eight days up to 16 days after which then it started decreasing. Study with multiple hosts revealed that the extent of translocation from hosts to sandal varied from 28.9% (coconut + Casuarina + rubber as host) to 78.5% ( Casuarina + rubber as hosts). Reverse translocation of 32P from sandal to host was also observed. The study concludes that it is not necessary to plant the host along with the sandal as it is practiced presently.