Morphological and physiological responses to water stress and potassium nutrition in Eucalyptus grandis Hill Ex Maiden seedlings

In this study, the response of Eucalyptus grandis seedlings to varied water availability and potassium fertilization in coarse-textured soil was investigated. The experiment took place in a greenhouse in Buenos Aires, Argentina, over 56 days, with 15 replicates for each treatment. We maintained pots in the non-water-limited group at field capacity (FC), while those in the water-restricted group were maintained at 40% FC. Each water regime received one of three potassium levels (K1, K2, and K3). We measured plant height and root-collar diameter periodically. At the end of the experiment, biomass allocation among plant parts was quantified. We also evaluated physiological traits by measuring stomatal conductance and relative water content (RWC). The results show that potassium fertilization did not improve seedling performance under water stress or enhance growth in well-watered seedlings. Water restriction was the main limiting factor. Keeping soil moisture at 40% of FC reduced height growth, root-collar diameter, biomass, and leaf area. It also negatively affected physiological traits such as stomatal conductance and RWC, but did not cause seedling mortality.