Looking for adjustments to severe drought in coffee: lessons of a rainfall exclusion plot in the Southern Brazil

Abstract

Rainfall exclusion experiments allow us assessing the effects of environmental stresses such as long-term water limitations on both leaf and canopy structural traits. This work aimed to evaluate how leaf anatomical traits and canopy development of productive coffee trees change when submitted to more dry conditions in the southern region of Minas Gerais - Brazil. The experimental plots have been set up in a plantation area in which is growing Coffea arabica L. cv. Mundo Novo- IAC 379-19, in a completely randomized arrangement, composed by three treatments: Control (C) - no gutter system; Control plus roof (Ĉ) and Exclusion system (E). Leaf anatomical and canopy traits were determined within a year at the end of each season: late Spring- 2015 (Sp), and late Summer (Su), late Autumn (Au) and late Winter (Wi) - 2016. During the studied period the rainfall exclusion condition led to a reduction in the relative water content (RWC) of leaves. In the leaf-level, as the dry condition increase, the leaves invested in thicker cuticles, reduced xylem and phloem areas and smaller stomata, especially with the rainfall exclusion. In the canopy-level, there was a remarkable reduction in leaf area index (LAI) especially in the winter as a strategy of reduction of transpiratory area, when the availability of water decreased around 25%. In a context of reduced water availability due to effects of climate change, coffee trees may be able to present modifications at both levels, to cope with the effects of this abiotic stress.