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

Abstract

Abstract:We assessed growth and physiological responses of Eucalyptus and Corymbia species to water limitation aiming to widen possibilities for plantations in dry climatic conditions. We selected 16 taxa: 4 Corymbia and 12 Eucalyptus species from the Subgenera Symphyomyrtus. Seedlings were evaluated from 100 to 170 days after sowing. Growth and physiological traits showed significant differences among taxa and between two levels of water availability. Water limitation significantly impacted biomass production and physiological characteristics, however in different levels. Leaf area and biomass production decreased 15%-48% under water limitation among taxa. Eucalyptus moluccana, CCV 2, and VM1 (drought tolerant clone) showed the largest decrease in leaf area. Transpiration across taxa decreased 30%-57% and photosynthesis 14%-48% under water limited condition. Taxa from cold environments were less responsive in leaf area reduction under water limitation, and taxa from Exsertaria section showed lower reduction in photosynthesis (E. camaldulensis showed the lowest reduction). Responses to water limitation are related to the environment of origin. E. molucana, the only Adnataria species from a high precipitation region (>1500 mm year´1), was one of the most sensitive in reduction of biomass production, different behavior from the other Adnataria species, originated in regions with rainfall <750 mm year´1. Water limitation increased leaf-level water use efficiency by 18% on average, 8% in E. longirostrata, and 28% in E. camaldulensis, E. brassiana, and E. crebra. Growth and physiological responses observed show the potential of different eucalypts taxa to tolerate water limited environments.

Selection of Eucalyptus grandis families across contrasting environmental conditions

“…The least productive (Figure 1). However, the rainfall in Itamarandiba during the trial period was nearly half of the historical average (2014 and 2015 rainfall < 600 mm), resulting in moderate and prolonged water stress, known to reduce eucalypt productivity (Silva et al 2016b, Gonçalves et al 2017). On the other hand, in Monte Dourado, the disease Cylindrocladium leaf spot was observed.…”

Variability and Plasticity in Cuticular Transpiration and Leaf Permeability Allow Differentiation of Eucalyptus Clones at an Early Age

“…is a drought-tolerant species [28], Eucalyptus globulus offers certain genotypes that potentially tolerate environments with low water availability [29], and the hybrid Eucalyptus × urograndis is usually sensitive to water deficit [30,31]. WUE relates photosynthetic rate or plant growth to water consumption and has been shown to be a useful physiological parameter to assess plant drought adaptation [22,32,33], and to differentiate the behavior of different taxa [28]. However, WUE is not always a constant trait of a given taxon: it varies according to a specific combination of conditions of the site, weather, and tree age [34].…”

Irrigation Regimes on Growth and Metabolic Processes of Enterolobium contortisiliquum Seedlings

“…Morphologically, E. contortisiliquum seedlings presented positive results when the RR12 irrigation regime (12 mm day -1 ) was applied. Silva et al (2016) studied the responses of water availability in sixteen species of the Eucalyptus genus to verify the negative effect of water restriction during seedling production. However, Dutra et al (2016) evaluated the effect of different substrates and irrigation regimes to report that the use of 4 mm day -1 was enough to produce healthy seedlings of Parapiptadenia rigida (Benth.)…”

“…The results show that water deficiency in the substrate has a significant influence on root growth, where this deficit increases the root biomass under stress. The contrasting response in the production of root biomass reflects a strategy used by different forest species (Dutra et al, 2016;Silva et al, 2016) in relation to carbon allocation. In general, water restriction induces carbon partitioning for root synthesis in order to increase the surface of fine roots, and thus, to increase the area of contact with the soil, which consequently enhances the capacity of water and nutrients absorption (Litton et al, 2007;Ryan et al, 2010).…”