In Eucalyptus plantations, coppice rotations often yield less than initial rotations. The TECHS project (Tolerance of Eucalyptus Clones to Hydric, Thermal and Biotic Stresses) studied short rotation coppicing across a 3000 km gradient. The main objective of this work was to compare the survival, sprouting, and initial growth of Eucalyptus clones managed and to examine factors that might influence the productivity of the coppice rotation: climate, genotypes, and stocking. Eight of the TECHS sites spread from latitudes 6° S to 30° S were included in the coppice study, with 17 genotypes at each site. The initial rotation had been planted at a 3 m × 3 m spacing and also in a spacing trial at densities from 500 to 3500 trees ha⁻¹. Six months after harvesting the initial Eucalyptus rotation, average survival was 88%, with tropical clones showing over twice the sprouting biomass (6.7 vs. 2.9 Mg ha⁻¹) and four times the woody biomass compared to subtropical clones (4.7 vs. 1.1 Mg ha⁻¹). Greater initial water deficits had stronger sprouting and growth. Clones with higher belowground carbon allocation in the initial rotation performed better in coppicing, and precipitation became more influential after 12 months. Drought and spacing trials significantly affected growth.

Aims: This objective of this work was to evaluate the effects of water deficiency on physiological aspects of oiticica plants, as well as the capacity of potassium fertilization to attenuate such effects. Study Design: The treatments were distributed in an entirely randomized design (DIC), consisting of a 4x4 factorial, with four levels of potassium (K) and four water turning, with five repetitions. Place and Duration of Study: The experiment was conducted in a shaded environment, with 50% light interception, in the Forest Nursery of UAEF/UFCG, between January 2020 and July 2020. Methodology: The relative water content (RWC), transpiration (E) and photosynthesis (A) rates, stomatal conductance (gs), and internal CO₂ concentration (Ci) were evaluated, and from the values of A and E, the intrinsic water use efficiency (EUAi) was calculated and, with the data of A and Ci, the carboxylation efficiency (A/Ci). Results: There was significant interaction of treatments in the parameters RWC, E, gs, A and EUAi and isolated effect of water turning on Ci and A/Ci. Irrigation daily or every five days provided the maintenance of higher water status and better stomatal behavior, and the plants were sensitive to water stress provided by longer water turnings (every 10 and 15 days). The fertilization with 100 and 150 mg dm^-3 of K kept the values of E and A high, even under low water availability. Conclusion: Potassium fertilization proved to be effective in attenuating the negative effects caused by water deficiency on gas exchange and WUEi of the seedlings, with highlights for 100 and 150 mg dm^-3 of K levels.

In Eucalyptus plantations, coppice rotations often yield less than initial rotations. The TECHS project (Tolerance of Eucalyptus Clones to Hydric, Thermal and Biotic Stresses) studied short rotation coppicing across a 3,000 km gradient. The main objective of this work was to compare the survival, sprouting and initial growth of Eucalyptus clones managed, and to examine factors that might influence the productivity of the coppice rotation: climate, genotypes and stocking. Eight of the TECHS sites spread from latitudes 6o S to 30o S were included in the coppice study, with 17 genotypes at each site. The initial rotation had been planted at a 3 x 3 m spacing, and also in a spacing trial at densities from 450 to 14,000 trees ha-1. Six months after harvesting the initial Eucalyptus rotation, average survival was 88%, with tropical clones showing over twice the sprouting biomass (6.7 vs 2.9 Mg ha-1) and four times the woody biomass compared to subtropical clones (4.7 vs 1.1 Mg ha-1). Greater initial water deficits had stronger sprouting and growth. Clones with higher belowground carbon allocation in the initial rotation performed better in coppicing, and precipitation became more influential after 12 months. Drought and spacing trial significantly affected growth.

DIAGNÓSTICO DA ARBORIZAÇÃO DO CAMPUS DE PATOS - PB