Leaf to Root Morphological and Anatomical Indicators of Drought Resistance in Coffea canephora After Two Stress Cycles

Abstract

Coffea canephora genotypes adopt distinct strategies to cope with drought and rehydration. We hypothesized that the greater drought tolerance of genotype ‘3V’ compared to ‘A1’, previously reflected in physiological and anatomical leaf traits after two water-stress (WS) cycles, could also be observed in P–V curve responses, root and branch anatomy, leaf midrib elongation (CVL), and root distribution. The ‘3V’ and ‘A1’ plants were grown under well-watered (WW) conditions and two cycles of water stress (WS). The ‘3V’ was more sensitive to WS, with reduced branch xylem vessel density (BXVD), while ‘A1’ demonstrated increased BXVD. Root xylem vessel area (RXVA) decreased to a greater extent in ‘3V’ than in ‘A1’, and both genotypes showed increased bulk elastic modulus. Regardless of water conditions, ‘A1’ maintained a higher relative leaf water content at the turgor loss point (RWCTLP). Morphological acclimation did not occur in the second WS cycle. The ‘3V’ plants developed greater root mass in deeper soil layers than ‘A1’ under the WS condition. These findings suggest that ‘A1’ follows a conservative drought-avoidance strategy with lower physio-morphological plasticity, while ‘3V’ exhibits greater drought tolerance. Such responses highlighted coordinated physiological, morphological, and anatomical adaptations of the above- and below-ground organs for resource acquisition and conservation under WS.