Plant water relations, crop yield and quality in coffee (Coffea arabica L.) as influenced by partial root zone drying and deficit irrigation.

Abstract

Recurrent drought is among the major factors constraining coffee production in Ethiopia. On the other hand, in most cases, there is shortage of water resources for irrigation during prolonged dry spells. Therefore, this study was conducted with the objective of developing an effective irrigation management strategy, which could minimize the adverse effect of drought on coffee production, save water and improve water use efficiency of this crop. Two deficit irrigation techniques: partial root zone drying (PRD) and normal deficit irrigation (NDI) were studied along with a well-watered (WW) treatment on six years old coffee (Coffea arabica L.) stand of cultivar F-59 in randomized complete block design with four replications. The experiment was conducted for 18 months at Jimma Agricultural Research Center of the Ethiopian Institute of Agricultural Research. Among the irrigation practices tested in the present study, full irrigation (WW) resulted in considerably higher soil moisture content, leaf relative water content (RWC), stomatal conductance (gs) and crop yield, compared to PRD and NDI. Yield components had also higher values under WW than in PRD and NDI treatments. However, the difference between WW and PRD was not significant for crop yield and for most of the yield components, and yet PRD and NDI significantly improved the quality of coffee beans. In addition, PRD saved 50% of the irrigation water required for WW and resulted in significantly higher irrigation water use efficiency (IWUE) than WW and NDI. Hence, it was concluded that PRD seems an effective irrigation strategy that could save water, increase IWUE and improve crop quality without a significant reduction in crop yield in areas where water is scarce for irrigation and the dry spells are prolonged.