Effect of the substitution of potassium by sodium on Eucalyptus grandis W. Hill ex Maiden wood, aiming to the expansion of forest plantations under hydric stress

Abstract

In Brazil, most plantations are generally established in regions of low fertility, low in potassium and subjected to long periods of drought. The expansion of forest plantations may be affected by climate change, with the change in the frequency and intensity of precipitation. The physiological mechanisms that trees hold to minimize the resulting phenomena from water deficit are based, among other mechanisms, in osmotic settings that in the presence of K+ and Na+, improves stomatal control preventing water loss and promoting the establishment and development of tree plantations. Thus, understanding the processes and interactions between potassium and sodium availability and operation of forest stands, especially the growth in diameter of the trunk and the formation of wood of trees becomes decisive. The possibility of full or partial replacement of sodium by potassium fertilization of forest plantations is of great interest to Brazil, reducing its dependence on fertilizer and production costs. In this context, an alternative to these evaluations are permanent dendrometers for measuring the stem diameter growth of trees, which have proved efficient, low cost, high accuracy and assessment of growth of the trunk in reduced time intervals. Moreover, the use of new technologies in Brazil and the latest equipment to characterize the quality of the wood, such as optical emission spectroscopy with laser-induced plasma (LIBS) and near infrared spectroscopy (NIR) allows the establishment standardized procedures and activities to determine with certainty the quality of wood used for various purposes. Given this, the present study aims at evaluating the replacement effect of potassium by sodium in diameter growth and wood quality of Eucalyptus grandis in order to guide the fertilizer with potassium and sodium in forest plantations subject to water stress caused by climate change. (AU)