Deciphering the importance of morphological aspects in drought tolerance in eucalyptus progenies

Water limitation is one of the factors that most impact plant growth and productivity, especially for Eucalyptus. For commercial eucalyptus plantations to develop properly, it is essential to select clones with drought-tolerant characteristics, especially in areas with low rainfall and well-defined dry periods. Accordingly, climate change, mainly related to increases in mean annual temperature, can lead to a more severe water deficit and ultimately harm plant development. Thus, the identification of indicators related to climatic variables enables the selection of clones with drought tolerance characteristics. Here, we used 27 families of eucalyptus progenies from crosses of plants with previously selected characteristics associated with drought tolerance, which were planted in a region characterized by high water deficiency. Sample harvesting was performed at 6, 18, and 30 months after planting, at the end of natural drought cycles. Meteorological data coupled with physiological analyses allow the early selection of Eucalyptus clones that are better able to tolerate recurrent drought events. Specific leaf area (SLA), leaf area (LA), length (L), width (W), and leaf water potential (Ψ_L) were analyzed. The parameters SLA, LA, and Ψ_L proved to be good bioindicators of Eucalyptus drought tolerance. Specific clones and progenies (e.g., GG2673, VM1, GG1923, GG1980, GG3389XGG4302, GG918XVS62, AEC2034xLR831, I3000XVM1, VM4XCAM, and VM1xVM4) were characterized by physiological adjustments and showed higher average annual volumetric increment (IMAvol) values and were assumed as genetic materials with potential drought tolerance.