Using internal plant water status as a criterion for scheduling irrigation in coffee in east of rift valley Kenya

Abstract

Relationship between leaf water potential and leaf growth rate is examined with the aim of determining the critical leaf water potential at which coffee leaves cease to grow. This was done in order to augment information on monitoring irrigation. Using cobalt chloride paper disk to change from blue to pink, with leaf water potential; under overcast and clear sky conditions, it was found that it takes 10, 7½ and 5 minutes at 10.30 - 11.30, 11.30 - 12.30 and 12.30 - 14.00 hours respectively. It is suggested that information on leaf growth rate which is an integral component of productivity can be used as an index to evaluate the productivity of coffee and that coffee should only be irrigated at - 20 bars as it is the critical point when growth ceases