A Comparative Study of Water Movement in Leaf Scorch Decline Affected and Healthy Coconut Palms using Lithium as a Non-Radioactive Tracer

Obstructions to the movement of water, by physical blockages in the vascular system, are a possible cause of the Leaf Scorch Decline (LSD) disorder of coconut palms. This hypothesis was tested by comparing the pattern of water movement in healthy and LSD-affected coconut palms, using Lithium, a non-radioactive tracer, as an indicator. Pattern of water transport in the leaf canopy of healthy and LSD-affected palms was similar but the quantities transported were different. Less water movement in moderate-LSD palms than in healthy and mild-LSD palms suggest the development of obstructions to water movement when the disorder increases in severity. Uptake of water into the root system was not affected by the LSD disorder. However, in moderate-LSD palms more water was retained in the roots than in healthy and mild-LSD palms. This also points to restrictions to water movement in the moderate-LSD palms. The relatively high amounts of Li retained in the roots of healthy and mild-LSD palms need further investigation. Key words: Leaf Scorch Decline, visible symptoms, pattern of water movement, non-radioactive tracer doi: 10.4038/cocos.v18i0.986 COCOS (2007), 1