Abstract:ABSTRACT.To evaluate the effects of hydric stress on CO 2 and H 2 O exchange, fivemonth-old Tabebuia aurea seedlings cultivated in planting bags were subjected to hydric stress by suppressing irrigation for 21 days. After 14 days without irrigation, the rates of transpiration, stomatal conductance and net photosynthesis in leaves were zero, while the hydric potential of leaves reached -2.4 MPa. After this point, daily irrigation was resumed, and the values of the measured variables recovered to initial levels … Show more
“…The maximum rate of CO 2 assimilation for control plants in this study was similar to that reported by Oliveira et al (2011) for five-month-old plants of the same species. However, the rates inversely correlated with the duration of flooding, resulting in lower values after 20 and 40 days of stress.…”
Section: Oliveira Akm E Gualtieri Scjsupporting
confidence: 77%
“…The leaf water potential of flooded plants was similar to that reported for control plants at 5 months by Oliveira et al (2011). The results obtained from this study indicated that the water potential of T. aurea is not strongly affected by flooding and remains constant.…”
-The Paratudo (Tabebuia aurea) is a species occurring in the Pantanal of Miranda, Mato Grosso do Sul, Brazil, an area characterized by seasonal flooding. To evaluate the tolerance of this plant to flooding, plants aged four months were grown in flooded soil and in non-flooded soil (control group). Stomatal conductance, transpiration and CO 2 assimilation were measured during the stress (48 days) and recovery (11 days) period, totalling 59 days. The values of stomatal conductance of the control group and stressed plants at the beginning of the flooded were 0.33 mol m . Flooded soil reduced photosynthesis and stomatal conductance, leading to the hypertrophy of the lenticels. These parameters recovered and after this period, and plants exhibited tolerance to flooding stress by reducing their physiological activities.Keywords: CO 2 assimilation; Hydric stress; Hypoxia tolerance.
TROCAS GASOSAS EM PLANTAS JOVENS DE Tabebuia aurea (Bignoniaceae Juss.) SUBMETIDAS A ESTRESSE POR ALAGAMENTORESUMO -O paratudo, Tabebuia aurea, é uma espécie de larga ocorrência no Pantanal de Miranda, Mato Grosso do Sul, uma área de inundação sazonal. Para determinar o grau de tolerância da espécie ao alagamento, um grupo de plantas com quatro meses de idade foi mantido em vasos alagados, além do grupo controle, com as taxas de condutância estomática, transpiração e assimilação de CO 2 determinadas durante o período de estresse (48 dias) e de recuperação (11 dias), totalizando 59 dias. Em relação aos valores obtidos, a condutância estomática, no início do alagamento, atingiu 0,33 mol m
“…The maximum rate of CO 2 assimilation for control plants in this study was similar to that reported by Oliveira et al (2011) for five-month-old plants of the same species. However, the rates inversely correlated with the duration of flooding, resulting in lower values after 20 and 40 days of stress.…”
Section: Oliveira Akm E Gualtieri Scjsupporting
confidence: 77%
“…The leaf water potential of flooded plants was similar to that reported for control plants at 5 months by Oliveira et al (2011). The results obtained from this study indicated that the water potential of T. aurea is not strongly affected by flooding and remains constant.…”
-The Paratudo (Tabebuia aurea) is a species occurring in the Pantanal of Miranda, Mato Grosso do Sul, Brazil, an area characterized by seasonal flooding. To evaluate the tolerance of this plant to flooding, plants aged four months were grown in flooded soil and in non-flooded soil (control group). Stomatal conductance, transpiration and CO 2 assimilation were measured during the stress (48 days) and recovery (11 days) period, totalling 59 days. The values of stomatal conductance of the control group and stressed plants at the beginning of the flooded were 0.33 mol m . Flooded soil reduced photosynthesis and stomatal conductance, leading to the hypertrophy of the lenticels. These parameters recovered and after this period, and plants exhibited tolerance to flooding stress by reducing their physiological activities.Keywords: CO 2 assimilation; Hydric stress; Hypoxia tolerance.
TROCAS GASOSAS EM PLANTAS JOVENS DE Tabebuia aurea (Bignoniaceae Juss.) SUBMETIDAS A ESTRESSE POR ALAGAMENTORESUMO -O paratudo, Tabebuia aurea, é uma espécie de larga ocorrência no Pantanal de Miranda, Mato Grosso do Sul, uma área de inundação sazonal. Para determinar o grau de tolerância da espécie ao alagamento, um grupo de plantas com quatro meses de idade foi mantido em vasos alagados, além do grupo controle, com as taxas de condutância estomática, transpiração e assimilação de CO 2 determinadas durante o período de estresse (48 dias) e de recuperação (11 dias), totalizando 59 dias. Em relação aos valores obtidos, a condutância estomática, no início do alagamento, atingiu 0,33 mol m
“…This behavior indicated that other factors influence CO 2 uptake. Further, it suggests the presence of chemical signals in the plants, such as abscisic acid, which control the stomatal opening during drought periods (Hirayama and Shinozaki, 2010;Oliveira et al, 2011). It constitutes a strategy used by the plants to reduce excessive water loss due to transpiration (Albuquerque et al, 2013) and therefore avoiding tissue dehydration, in addition to permitting the maintenance of the integrity of the water transport system and the development of water potential, when the soil is undergoing progressive drought (Magalhães et al, 2008).…”
The objective of this study is to evaluate the effect of water deficit and the recovery potential following rehydration, on the metabolism of Campomanesia xanthocarpa seedlings. The seedlings were distributed in two groups: the first group was the control, in which, plants were hydrated periodically in order to maintain 70% water holding capacity and the second was the treatment group characterized by stress, in which irrigation was suspended until the photosynthetic rate showed levels close to zero, at which point the plants were once again rehydrated with subsequent daily irrigation for one week, maintaining the water holding capacity at 70%. C. xanthocarpa shows a reduction in stomatal conductance and photosystem PSII efficiency. Water deficit decreases the water potential in the leaves and all the traits of the photosynthetic metabolism in C. xanthocarpa seedlings in twenty days of suspension of irrigation. These are later recovered with the re-establishment of the water supply. However, exposure of the seedlings to a second cycle of water deficit during the evaluation period demonstrated that the metabolism traits do not re-establish equilibrium.
“…Souza et al (2010) studied four species under drought, and did not observe lower conductance rates in all these ones studied, except for Brosimum guianensis. Although Oliveira et al (2011) found similar behavior for five-month-old T. aurea, with declining conductance rates during water stress, the lowest values were found after 14 days of stress. The data obtained for this experiment, with values of 0.0 mol m -2 s -1 after 22 days of stress once more indicate that as individuals become older, their ability to resist to water stress increases.…”
Section: Stomatal Conductancementioning
confidence: 68%
“…This response (leaflets water potential, decrease) was expected, once Mansur and Barbosa (2000) studied Caatinga species, and found that leaflets water potential is reduced by decreasing the availability of water in the soil, causing loss of turgor and stomatal closure. Oliveira et al (2011) studied individuals of T. aurea under stress, and found similar behavior for five-month-old T. aurea, with values between 0.4 and -0.6 MPa for the control plants, and until -2.6 MPa for stressed plants. However, plants with higher growth time (this study) take longer to reach the lowest value of MPa (23 days), while young plants take 14 days, indicating that the longer the growth, the greater the resistance to water stress is.…”
ABSTRACT:The paratudo, Tabebuia aurea, is a common Brazilian tree from the Pantanal wetland from Miranda, Mato Grosso do Sul, an area with hydric seasonality. To evaluate the effects of water stress on CO 2 exchange, ten-month-old T. aurea seedlings cultivated in planting bags were subjected to water stress by suppressing irrigation for 23 days. Stomatal conductance, transpiration rate, and photosynthetic rate were measured during the stress and recovery period, totaling 28 days, using an infrared portable analyzer. After 23 days without irrigation, the transpiration, stomatal conductance, and net photosynthesis rates in leaflets were zero, while the leaflets water potential reached -2.6 MPa. After this point, daily irrigation was resumed, and the values of the measured variables recovered to the initial levels after 96 hours (transpiration rate from 2.0 to 2.6 mmol m -2 s -1 ; stomatal conductance rate from 0.12 to 0.18 mol m -2 s -1 and photosynthesis rate from 8.1 to 9.5 µmol m -2 s -1 ). Furthermore, the hydric potential values were similar to those observed at the beginning of the experiment (-0.5 MPa). The results showed that T. aurea has tolerance to drought, allowing their survival in areas subjected to periodic water stress.
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