Effects of potassium and sodium supply on drought‐adaptive mechanisms in Eucalyptus grandis plantations

Abstract

SummaryA basic understanding of nutrition effects on the mechanisms involved in tree response to drought is essential under a future drier climate.A large-scale throughfall exclusion experiment was set up in Brazil to gain an insight into the effects of potassium (K) and sodium (Na) nutrition on tree structural and physiological adjustments to water deficit.Regardless of the water supply, K and Na supply greatly increased growth and leaf area index (LAI) of Eucalyptus grandis trees over the first 3 yr after planting. Excluding 37% of throughfall reduced above-ground biomass accumulation in the third year after planting for K-supplied trees only. E. grandis trees were scarcely sensitive to drought as a result of the utilization of water stored in deep soil layers after clear-cutting the previous plantation. Trees coped with water restriction through stomatal closure (isohydrodynamic behavior), osmotic adjustment and decrease in LAI. Additionally, droughted trees showed higher phloem sap sugar concentrations.K and Na supply increased maximum stomatal conductance, and the high water requirements of fertilized trees increased water stress during dry periods. Fertilization regimes should be revisited in a future drier climate in order to find the right balance between improving tree growth and limiting water shortage.

Seedling Growth and Physiological Responses of Sixteen Eucalypt Taxa under Controlled Water Regime

“…Eucalypts show several adaptations to avoid or tolerate environmental stresses [5] such as reduction in canopy leaf area; increased partitioning of carbohydrates to root growth; change in size, thickness, and distribution of leaves; stomatal closure; and production of osmoregulators [6][7][8][9]. However, depending on the frequency, duration, and severity of droughts, plant age and plasticity (within and among species), and changes in structural, physiological, biochemical characteristics may not be enough to avoid significant reduction in growth and mortality [4,10,11].…”

Nutritional Efficiency of Eucalyptus Clones Under Water Stress

“…Aside from stomatal limitations, water stress can cause oxidative damage, leading to chlorophyll degradation, as described for Eucalyptus (Coscolin et al, 2011). Therefore, lower UEK would probably be advantageous for drought tolerance, since K affects the stomatal control directly, and K deficiency causes a reduction in the osmotic pressure of the guard cells, reducing their swelling and leading to partial stomatal closure (Battie-Laclau et al, 2014). These mechanisms establish a tighter control over leaf water loss and a more conservative strategy of water use in plants.…”

Crescimento, nutrição mineral e eficiência do uso da água em povoamento de eucalipto fertilizado com fontes alternativas ao KCl

“…Inicialme nte, foram realizados estudos de fertilização com N, P e K, e a disponibilidade de água para as árvores, tendo em vista suas rápidas e significativas respostas em crescimento às aplicações (COLE et al, 1990;HERBERT, 1990). Estudos recentes demonstram que o K é um dos nutrientes que mais afeta a eficiência do uso da água e o crescimento das árvores de eucalipto, bem como as características morfológicas, anatômicas e ecofisiológicas das plantas (BATTIE-LACLAU et al, 2013, 2014a, 2014bCRISTINA et al, 2015). Estudos similares a estes foram conduzidos com Na, tendo em vista a possibilidade de substituição parcial do K por esse elemento SETTE JÚNIOR et al, 2013).…”

“…Battie- Laclau et al (2014a) hídrico foliar e a reserva de água no solo (BATTIE-LACLAU et al, 2013, 2014b.…”

“…potencial hidrodinâmico da água da raiz para a parte aérea das plantas (Ψplanta), subtraindo-se os Ψwf (antemanhã -meio dia) (FRANKS et al 2007, BATTIE-LACLAU et al, 2014b …”