A simple technique for timing irrigation in coffee using cobalt chloride paper disks

Abstract

A simple technique for determining the time to irrigate coffee using leaf water potential as an indicator of internal water belance is described. The technique is based on the time taken for dry cobalt chloride paper disk to change its colour from blue to pink when attached to the abaxial side of the leaf. If this is more than 5 min during the time when trees experience maximum diurnal stress (i. e. between 12.30 and 14.00 h) and leaf water potential is close to −20 bar trees should be irrigated, otherwise not.