Ecofisiologia de mudas clonais de Eucalyptus urograndis i144 submetidas ao estresse salino

Abstract

Eucalyptus is a species that is increasingly prominent in the economic sector, especially when it comes to wood production. The genus presents highly productive species in the production of forest raw materials, including its clones, such as i144. Although eucalyptus plantations are easily adapted to tropical conditions, tolerant to drought and fast growing, the absence of good quality water resources for agriculture means that rural producers use brackish water for moisture, which contains high concentrations of of salts above ideal. Therefore, the objective of this work was to evaluate the physiological behavior of Eucalyptus urograndis i144 seedlings, subjected to different levels of salinity. The experiment was carried out at the Production Technology Laboratory – Silviculture and Forest Nurseries Sector, on the Engineering and Agricultural Sciences campus, at the Federal University of Alagoas. Eucalyptus urograndis i144 seedlings were purchased from a commercial nursery. The experimental design adopted was completely randomized, corresponding to four saline concentrations: Control - 0 mM NaCl, 50 mM NaCl, 100 mM NaCl and 150 mM NaCl, with 5 replications each, totaling 20 seedlings. The saline solution was prepared using analytical salt and distilled water. During the research, the variables were evaluated: plant height, diameter, number of leaves per plant, and, at the end of the experiment, it was possible to evaluate the leaf area, specific leaf area, leaf area ratio, relative water content, percentage of absolute integrity, percentage of relative integrity and percentage of membrane damage, determination of chlorophyll a, b, a/b, total and carotenoids, root dry biomass, stem dry biomass, leaf dry biomass and total dry biomass, in grams . Next, the allocation of biomass to the root, stem, leaf and finally, the root/part area ratio was determined. In dry matter production and growth, the control (0 mM), and the 50 mM and 100 mM concentrations did not differ statistically from each other. In the production of chlorophyll a, b, total and carotenoids, the 100 mM NaCl level obtained the greatest prominence among the others, however, the seedlings at the 150 mM NaCl concentration were not negatively affected in the root dry biomass and root/root ratio variables. aerial part. The use of saline water for the production of the i144 eucalyptus clone is recommended up to a level of 100 mM NaCl.

Key words: Seedling production; salinity; eucalyptus; silviculture