Stomatal responses of Eucalyptus species to elevated CO2 concentration and drought stress

Abstract

Five species of Eucalyptus (E. grandis, E. urophylla, E. camaldulensis, E. torelliana, and E. phaeotrica), among the ten species most commonly used in large scale plantations, were selected for studies on the effects of elevated CO 2 concentration [CO 2 ] and drought stress on stomatal responses of 2.5-month old seedlings. The first three species belong to the subgenus Smphyomyrtus, whereas the fourth species belongs to the subgenus Corymbia and E. phaeotrica is from the subgenus Monocalyptus. Seedlings were grown in four pairs of open-top chambers, arranged to have 2 plants of each species in each chamber, with four replications in each of two CO 2 concentrations: 350 ± 30 µmol mol -1 and 700 ± 30 µmol mol -1 . After 100 days in the chambers, a series of gas exchange measurements were made. Half the plants in each chamber, one plant per species per chamber, were drought-stressed by withholding irrigation, while the remaining plants continued to be watered daily. Drought stress decreased stomatal conductance, photosynthesis and transpiration rates in all the species. The effect of drought stress on stomatal closure was similar in both [CO 2 ]. The positive effects of elevated [CO 2 ] on photosynthesis and water use efficiency were maintained longer during the stress period than under well-watered conditions. The photosynthetic rate of E. phaeotrica was higher even in the fourth day of the drought stress. Drought stress increased photoinhibition of photosynthesis, as measured by chlorophyll fluorescence, which varied among the species, as well as in relation to [CO 2 ]. The results are in agreement with observed differences in stomatal responses between some eucalyptus species of the subgenera Symphyomyrtus and Monocalyptus. Key words: eucalyptus physiology, water use efficiency, drought tolerance, CO 2 adaptation RESPOSTA ESTOMÁTICA AO AUMENTO DA CONCENTRAÇÃO DO CO 2 ATMOSFÉRICO E AO ESTRESSE HÍDRICO DE ESPÉCIES DE EUCALYPTUSRESUMO: Cinco espécies de Eucalyptus (E. grandis, E. urophylla, E. Camaldulensis, E. torelliana e E. phaeotrica), dentre as dez espécies mais utilizadas em plantações florestais de larga escala, foram submetidas ao aumento do CO 2 e à interação deste com estresse hídrico para avaliar seu comportamento estomático. As três primeiras espécies pertencem ao subgênero Symphyomyrtus, a quarta espécie é do subgênero Corymbia e o E. Phaeotrica pertence ao subgênero Monocalyptus. Mudas destas espécies com idade de 2,5 meses foram cultivadas em quatro pares de câmaras de topo aberto, com duas plantas de cada espécie por câmara e quatro repetições em duas concentrações de CO 2 : 350 ± 30 µmol mol -1 e 700 ± 30 µmol mol -1 . Após 100 dias de crescimento nas câmaras, medições de trocas gasosas foram realizadas, após o que metade das plantas em cada câmara foi submetida ao estresse hídrico pela supressão da irrigação, permanecendo as demais plantas sob irrigação diária. O estresse hídrico reduziu a condutância estomática, a fotossíntese e as taxas de transpiração em todas as espécies. O efeito...

Physiological changes in eucalyptus hybrids under different irrigation regimes

“…This suggests that photoinhibition, often considered one of the effects of water stress (BJÖRKMAN;DEMMING, 1987;MOSETI;DINTWE, 2011), did not occur in this experiment, as observed by Rolando and Litttle (2008) in seedlings of E. grandis, and by Correia et al (2014) in E. globules subjected to water stress. Like those authors, it is possible to conclude that the Fv/Fm ratio does not reflect the water status of the plants, differing from results found by Lima, Rhizopoulou and Jarvis (2003). When a plant has its photosynthetic apparatus intact, the Fv/Fm ratio is close to 0.82, while a fall in this ratio reflects the presence of photoinhibition damage to the reaction centres of photosystem II (BJORKMAN;DEMMING, 1987).…”

“…The physiological and biochemical changes most commonly observed as the responses of plants to drought include closure of the stomata (with a consequent reduction in stomatal conductance, the rate of photosynthesis and transpiration), reduced water potential and water content of the leaves, an increase in the synthesis of osmoprotectors (proline and sugars), protein degradation (FANAEI et al, 2009) and a reduction in the photochemical efficiency of photosystem II, given by the ratio between the variable and maximal fluorescence -Fv/ Fm (BJÖRKMAN; DEMMING, 1987;LIMA, JARVIS, RHIZOPOULOU, 2003;MOSETI;DINTWE, 2011).…”

Effect of soil water availability on gas exchange in young trees of Eucalyptus grandis W. Hill ex Maiden

“…nitens, andWhitehead &Beadle (2004), Mendes, de Paula, Scarpinatti &de Paula (2013), andEl-Sharkawy et al (1985), in E. deglupta and E. citriodora. Lima et al (2003), found in several Eucalyptus species (E. grandis, E. urophilla, E. camaldulensis, E. torelliana and E. phaeotrica) photosynthesis rates between 25-30 μmol CO 2 m -2 s -1 with atmospheric CO 2 concentrations of 700 ppm (± 30) in the dry season, whereas rates of photosynthesis were 10-15 μmol CO 2 m -2 s -1 at normal concentrations of 350 ppm (± 30).…”

“…Research conducted by Close & Davidson (2003), in E. nitens, Sena &Kozlowski (1980), in E. camaldulensis andE. globulus, andLima, Jarvis, &Rhizopoulou (2003), in E. grandis, E. urophilla, E. camaldulensis, E. torelliana andE. phaeotrica, show the formation of adventitious roots and aerenchyma in response to periods of prolonged waterlogging, in addition to reducing the photosynthesis rate and significantly decreasing plant height and root and leaf production in trees of E. robusta (Clemens, Kirk, & Mills, 1978).…”

Soil attributes and wood quality for pulp production in plantations of Eucalyptus grandis clone

“…The positive influence of clay content on productivity is mainly due to increase of available water content in the soil (Figure 4). Lopes (1977) also found higher Zakia, 1998;Lima et al, 2003). Because of this, the soil's water regime is one of the most important factors that determine productive capacity (Melo et al, 1995;Leite, 1996).…”