Growth, biomass partitioning, leaf traits, stomatal traits and photoprotective/antioxidant compounds of four native desert woody plants under two different irrigation regimes

Name: Growth, biomass partitioning, leaf traits, stomatal traits and photoprotective/antioxidant compounds of four native desert woody plants under two different irrigation regimes
Keywords: Phenotypic plasticity

Datos de investigación

Growth, biomass partitioning, leaf traits, stomatal traits and photoprotective/antioxidant compounds of four native desert woody plants under two different irrigation regimes

Autores: Biruk, Lucia Nadia Icon

; Guevara, Aranzazù Icon

; Gonzalez, Carina Veronica Icon

; Rovida Kojima, Elisa Akemi Icon

; Fernandez, Maria Elena Icon

; Giordano, Carla Valeria Icon

Colaboradores: Debandi, Hugo Alejandro Icon

; Frete, Juan Francisco; Gazalez Vargas, Gabriela Jesús; Zalazar, Gabriel Esteban; Zalazar, Gualberto Icon

Publicador: Consejo Nacional de Investigaciones Científicas y Técnicas

Fecha de depósito: 12/02/2025

Fecha de recolección: 14/10/2014-10/02/2016

Clasificación temática:

Ciencias de las Plantas, Botánica; Otras Ciencias Agrícolas; Silvicultura

Resumen

We studied four woody species of the Monte Central desert: Bulnesia retama (Gillies ex Hook. & Arn.) Griseb., and three Neltuma spp. (ex Prosopis); Neltuma argentina Burkart, Neltuma flexuosa DC., and Neltuma alpataco Phil. We carried out a pot experiment with two levels of irrigation (high and low-water supply) in a glasshouse, where biomass production, stem growth, biomass allocation, total leaf area, leaf size, specific leaf area; stomata size, density and index; photoprotective and antioxidant compounds were measured.

Métodos

We studied four woody species of the Monte Central: Bulnesia retama (Gillies ex Hook. & Arn.) Griseb., and three Neltuma spp. (ex Prosopis); Neltuma argentina Burkart, Neltuma flexuosa DC., and Neltuma alpataco Phil. We carried out a pot experiment with two levels of irrigation in a glasshouse at IADIZA, CONICET, Argentina (32º 52' S; 68º 49' W). The glasshouse has no temperature control and was used to exclude natural rainfall. We pooled all the seeds collected of each species, and randomly selected the ones that were sown in the experiment. The Neltuma spp. seeds were previously scarified with sandpaper. We sowed seeds in 5 L pots filled with 4.5 kg of commercial sand, a similar soil texture to that in the field (pH 8.03; electrical conductivity 1.91 dS m-1; total N 73 mg kg-1; N-NH4 36 mg kg-1; N-N03 12 mg kg-1; P-H2C03 2.3 mg kg-1, K 76 mg 1cg-1). We established two water treatments, low and high water availability (LW and HW). The LW treatment was to reflect the water stress situation to which plants are commonly subjected in the field, so we defined the relative water content of the substrate (RWC; % w/w) for this treatment on the basis of field records. During the frequent and prolonged periods of drought in the Monte Central, the soil RWC ranges from 0.5 to 2% (Guevara et al. 2018). In the field, we recorded leaf water potential values in N. flexuosa at midday around - 4.5 MPa (Giordano et al. 2011; Guevara et al. 2018), recording values up to more than - 10 MPa in B. retama (unpublished data) that exceeded the measuring capacity of the pressure chamber, so applying water stress to these species implies watering them extremely little. As we decided to work with a sandy substrate to replicate the field-like conditions as much as possible and knowing that this type of substrate has a dual behaviour in terms of water retention, sharply lowering its water potential when dry, we decided on the RWC ranges of the substrate for each treatment based on the water retention curve. As the equipment available in specialised soil laboratories only records up to - 2 MPa, we made the water retention curve by measuring the pre-dawn (PD) leaf water potential of small N. flexuosa seedlings growing in small pots in the same substrate as the experiment, subjected to increasing water stress, as detailed in Guevara and Giordano (2015). The PD leaf water potential of small seedlings in equilibrium with the substrate is an indicator of the water potential of the substrate. Based on the curve obtained, we decided to establish the two treatments as follows: LW: pots were watered to -4% RWC of the substrate and allowed to dry to -0.5%, corresponding to the exponential phase of the relationship between RWC and water potential (from approx. - 0.5 MPa to less than - 8 MPa); HW: pots were watered to -14% RWC of the substrate and allowed to dry to - 6% (fairly constant value of water potential, above - 0.5 MPa). As a result of this irrigation scheme, the RWC of the substrate of each treatment fluctuated. The LW treatment, based on the water retention curve of the substrate, would keep the plants in a fluctuation between no stress (immediately after the irrigation event) and increasing water stress (as the substrate dries out), whereas the HW treatment would keep the plants in a continuous situation of no stress. We watered the pots automatically with drippers and an irrigation controller, adjusting the watering time (i.e. total volume of water per irrigation event) and the interval between watering events according to the RWC of the substrate, which was monitored gravimetrically approximately twice a week. The time interval between irrigation events varied depending on the environmental conditions and plant growth. We started applying the water treatments on 14th October 2014, 30 days after planting. The experiment ended on I0th February 2016, spanning 484 days (1 year, 3 months, 27 days). Thirty plants of each species were placed in each treatment. Environmental conditions inside the glasshouse in summer (when these plants are actively growing) were mean daily temperature 29.1 (±0.1) ºC; maximum 46.4 (±0.1) ºC and minimum 11.8 (±0.1) ºC; mean RH 34.6 (± 0.1) %, maximum 93 .8 (± 0.1) % and minimum de 21.2 (±0.1) %, measured with a HOBO® data logger (HOS- 003-02, Onset Computer Corporation, Bourne, USA). These environmental conditions were similar to those at the Telteca Natural Reserve (IADIZA environmental web https://www.mendoza-conicet.gob.ar/ladyot/red_iadiza/ index.htm). Our own air temperature measurements in the field between January and February 2019 recorded 20 days with temperatures over 50 ºC, and 50 days with temperatures between 40 and 50 ºC (Biruk 2021). The photosynthetically active radiation at midday inside the glasshouse was 1244 µmol m-2 s-1• lt was measured with a Skye SKP 215 (400-700 nm) hemispherical sensor attached to the SpectroSense + 2 sensor (Skye Instruments Ltd, Powys, UK). The experiment followed a 2 X 4 factorial design, with water treatments (2 levels) and species ( 4 levels) as fixed factors. The experimental units (individual plants in a pot) were placed in the space systematically according to the restrictions imposed by the irrigation system, so that the treatments and species were distributed homogeneously and without spatial biases. Each experimental unit (individual plant) was assigned randomly to each treatment. Pre-dawn leaf water potential and Substrate relative water content: The water treatments applied were based on the water retention curve of the substrate, but the level of water stress experienced by each species may vary depending on its physiology. To get a measure of the water status of the plants, we measured the Pre-Dawn (PD) leaf water potential in 6 plants of each species and treatment in the summer of the second growing season (Dec 30, 2015). To do this, we covered the selected plants with black polyethylene bags to prevent transpiration, at the end of the photoperiod, and measured the leaf water potential PD with a pressure chamber (2.5 + 10 Model, Bio-Control, Buenos Aires, Argentina)- 2 h before dawn using one branch < 2 mm per plant (Scholander et al. 1965). We determine the relative water content of the substrate by gravietric method. Por total biomass {TB), we harvested 9 to 12 plants per treatment at the end of the experiment, and dried the roots, stems and leaves to a constant weight at 60 ºC, measured on a precision scale. The root collar diameter (RCD), a growth indicator that is easier to measure than biomass, was measured on all plants with a calliper. Biomass partitioning traits: Leaf mass ratio (LMR), stem mass ratio (SMR), root mass ratio (RMR) and root to shoot ratio (R:S) were calculated from the dry weights of different plant organs. Leaf traits: Neltuma spp. (ex Prosopis) have bipinnately compound leaves, with mostly two, and sometimes four pinnas (pri-mary division), with many pinnules (secondary divisions). Bulnesía retama has pinnately compound leaves, each with two to six pinnas. The leaves of Neltuma spp. close quickly if dried or handled (subfamily Mimosoideae), so it is very diffi.cult to measure them in an area folio-meter. So, we generated equations that would allow us to calculate the leaf surface area (LSA) using non-destructive and easily measured variables, such as length (L) or width (W) of pinnas (in the case of Neltuma spp.) or leaves (in the case of B. retama). To do this, we harvested about 100 expanded leaves of each species and calculated linear regressions between LSA, pinna or leaf L, and pinna or leaf W. The leaf surface area of the leaves used to make these regressions was measured in photographs using lmage J (v. l.51j8, National lnstitute of Health, Maryland, USA). We finally used pinna L to estímate P. argentina and P. alpataco LSA; and we used pinna or leaf W to estímate P. flexuosa and B. retama LSA, respectively. Leaf Mass Area (LMA) was calculated by measuring and weighing (after drying at 60 ºC until constant weight) a subset of expanded leaves from eight plants per species and treatment (three leaves/plant). For total plant Leaf Arca (LA), we added up the LSA of all the leaves in the plant. Leaf Area Ratio (LAR) was calculated as LA/TB. Stomata traits: For the determination of stomata size and frequency, we made epidermal prints of the middle portions of the pinnas (B. retama) or pinnules (Neltuma spp.), as described in (Giordano et al. 2011), and took photographs using an optical microscope coupled to a digital camera (DM500/ICC50HD, Leica Microsystems, Wetzlar, Germany) at lOOx magnification. Stomata and epidermal cells were counted in six 0.16 mm2 areas of the same leaf (three areas from the adaxial leaf surface and three areas from the abaxial leaf surface) and an average value was calculated per leaf from the six photographs. We measured 10 plants per species and treatment (3 leaves/plant). Photoprotective/antioxidant compounds: For Anthocyanins (AN) and Flavonoids (FLA) we measured 10 plants per species and treatment. We placed a single frozen leaf in a 10 mL of hydrogen chloride-methanol (HC1-CH30H) solution (1 % w/v) at - 18 ºC in darkness for 48 h. We read the absorbance of the extract at 280 and 520 nm in a UV-visible spectroradiometer (UV-vis Spectrum SP-2000; Shangai, China) for determination of the total FLA and AN content respectively, and expressed them per unit of LA (Mazza et al. 2000; González et al. 2016). Epicuticular Waxes (WAX) were measured in 10 plants per species and treatment. The waxes were removed by immersion of 6 frozen leaves in 1 mL of chloroform (CHCl3), followed by stirring (30 s). The chloroform was allowed to evaporate under a fume hood at room temperature. The amount of extracted WAX was calculated as the vial weight after wax extraction-empty vial weight, and expressed per unit of LA (Qaderi et al. 2002; Berli et al. 2013). Chlorophyll (CHL) and Carotenoids (CAR) content was measured in 5 plants of B. retama and P.argentina, and in 10 plants of N. flexuosa and N. alpataco, following Chapelle et al. (1992) with modifications. We placed 0.25--0.50 mg of frozen leaves in 10 mL of dimethyl sulfoxide (DMSO) at 90ºC in darkness for 75 min, and measured the absorbance of the extract at 665, 649 and 480 nm in a UV-visible spectroradiometer. The CHL and CAR concentration was calculated according to (Welburn 1994).

Palabras clave: Phenotypic plasticity, Drylands, Neltuma, Bulnesia, Monte Central

Alcance geográfico

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Identificador del recurso

URI: http://hdl.handle.net/11336/254112

Colecciones

Datos de Investigación(CCT - MAR DEL PLATA)
Datos de Investigación de CTRO.CIENTIFICO TECNOL.CONICET - MAR DEL PLATA

Datos de Investigación(IADIZA)
Datos de Investigación de INST. ARG DE INVEST. DE LAS ZONAS ARIDAS

Datos de Investigación(IBAM)
Datos de Investigación de INST.DE BIOLOGIA AGRICOLA DE MENDOZA

Citación

Biruk, Lucia Nadia; Guevara, Aranzazù; Gonzalez, Carina Veronica; Rovida Kojima, Elisa Akemi; Fernandez, Maria Elena; Giordano, Carla Valeria; (2025): Growth, biomass partitioning, leaf traits, stomatal traits and photoprotective/antioxidant compounds of four native desert woody plants under two different irrigation regimes. Consejo Nacional de Investigaciones Científicas y Técnicas. (dataset). http://hdl.handle.net/11336/254112

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