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While peach tree is very sensitive to waterlogging, there are no works on the effect of the flooding over only part of its root system. The objective of this work was to investigate physiological and growth responses of Nemared rootstock... more
While peach tree is very sensitive to waterlogging, there are no works on the effect of the flooding over only part of its root system. The objective of this work was to investigate physiological and growth responses of Nemared rootstock to partial flooding of roots. Treatments were performed for 6-days: control trees, half-flooded, and fully-flooded. Both flooding treatments negatively affected the vegetative growth, stomatal conductance, chlorophyll content and leaf water potential. The response observed in the half-flooded treatment was intermediate between the control and fully-flooded treatment. The fastest response of stomatal conductance to soil flooding, before differences among treatments in leaf water potential were perceived, suggested that there should be a stomatal closure mechanism that responds to a signal that arises from flooded roots. The importance of this work, lies in showing the negative effects of unnoticed and partial floods, frequently occurring in peach trees.
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The aerial growth dynamics of the shoots of the widespread turfgrass Paspalum vaginatum was studied. With the aim of identifying quantitative differential features between two genotypes, plants were cultivated outdoors in pots during two... more
The aerial growth dynamics of the shoots of the widespread turfgrass Paspalum vaginatum was studied. With the aim of identifying quantitative differential features between two genotypes, plants were cultivated outdoors in pots during two consecutive summers. Axes of different branching order were marked for periodical observation to quantify internode production rate, axis production rate, covering rate and reproductive effort. The genotypes differed significantly in the following quantitative features: plagiotropic vs. orthotropic axes proportion, internode production rate, flowering vs. vegetative tiller ratio, vegetative cover and spatial distribution of the canopy. Knowledge of these features may help to understand the great plasticity and adaptability of this species to multiple environmental conditions.
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Abstract In fruit trees, flooding stress can affect plant survival and growth, and tolerance to root anoxia is determined by rootstock characteristics. Similarly to almond, peach trees are also among the Prunus species proving most... more
Abstract In fruit trees, flooding stress can affect plant survival and growth, and tolerance to root anoxia is determined by rootstock characteristics. Similarly to almond, peach trees are also among the Prunus species proving most susceptible to root anoxia in flooded soils. The aim of our study was to investigate the short-term responses to flooding of different Prunus rootstocks, in terms of growth and development and physiological variables. Flood treatments were continuously applied for 6 days to myrobalan plum Sansavini 2/5 (Mr. S. 2/5), Monegro and Nemared peach rootstocks. Trees that were not exposed to flooding served as controls. Physiological and growth variables were evaluated. Flooding negatively affected net photosynthesis (Pn), leaf conductance (gs) and water potential (Ѱ w ) in Monegro and Nemared but not in Mr. S. 2/5 rootstock. However, flooding treatments did not affect the intercellular concentration of CO 2 (Ci) in any of the rootstocks. We propose that the lack of alterations in Ci indicates that the processes related to photosynthetic metabolism are affected simultaneously with stomatal closure. Flooding only reduced the leaf growth of Monegro and Nemared rootstocks. The Mr. S. 2/5 rootstock had the highest constitutive root porosity, which increased its tolerance to flooding compared to the other rootstocks. The differences in the responses to flooding of various rootstocks should be considered in production settings where it is not possible to properly control irrigation to prevent short periods of flooding or in soils that do not drain irrigation or rain water quickly.
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Seed germination of the kiwifruit (Actinidia deliciosa A. Chev. C.F. Liang and A.R. Ferguson), a deciduous, perennial vine, is low because of seed dormancy. The main purpose of this study was to characterize kiwifruit seed dormancy and... more
Seed germination of the kiwifruit (Actinidia deliciosa A. Chev. C.F. Liang and A.R. Ferguson), a deciduous, perennial vine, is low because of seed dormancy. The main purpose of this study was to characterize kiwifruit seed dormancy and germination in response to environmental factors such as temperature and light. Dormancy of hydrated seeds is alleviated by the perception of a period at low temperatures (stratification) of at least 3 weeks at 2 or 5°C. Alleviation of dormancy is accomplished by incubation at fluctuating temperatures (20/30°C). A red light pulse did not affect germination, whereas a far-red light pulse strongly inhibited germination. This inhibition was readily reverted by a second pulse of red light, indicating that phytochromes are also involved in dormancy alleviation. Although seed germination was inhibited by the fruit pulp, the latter prevented neither perception of low temperature nor changes in the light sensitivity of the seeds. Therefore, it can be advanced...
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Our aim was to search for specific seed germinative strategies related to flooding escape in Setaria parviflora, a common species across the Americas. For this purpose, we investigated induction after floods, in relation to fluctuating... more
Our aim was to search for specific seed germinative strategies related to flooding escape in Setaria parviflora, a common species across the Americas. For this purpose, we investigated induction after floods, in relation to fluctuating temperature requirements for germination in seeds from mountain, floodplain and successional grasslands. A laboratory experiment was conducted in which seeds were imbibed or immersed in water at 5°C. Seeds were also buried in flood-prone and upland grasslands and exhumed during the flooding season. Additionally, seeds were buried in flooded or drained grassland mesocosms. Germination of exhumed seeds was assayed at 25°C or at 20°C/30°C in the dark or in the presence of red light pulses. After submergence or soil flooding, a high fraction (>32%) of seeds from the floodplain required fluctuating temperatures to germinate. In contrast, seeds from the mountains showed maximum differences in germination between fluctuating and constant temperature treatment only after imbibition (35%) or in non-flooded soil conditions (40%). The fluctuating temperature requirement was not clearly related to the foregoing conditions in the successional grassland seeds. Maximum germination could also be attained with red light pulses to seeds from mountain and successional grasslands. Results show that the fluctuating temperature requirement might help floodplain seeds to germinate after floods, indicating a unique feature of the dormancy of S. parviflora seeds from floodplains, which suggests an adaptive advantage aimed at postponing emergence during inundation periods. In contrast, the fluctuating temperature required for germination among seeds from mountain and successional grasslands show its importance for gap detection.
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ABSTRACT Jatropha curcas is a promissory species for biodiesel production. Chilling and freezing stress are major environmental constraints for its establishment as a result of the injury provoked on leaf photosynthetic apparatus. This... more
ABSTRACT Jatropha curcas is a promissory species for biodiesel production. Chilling and freezing stress are major environmental constraints for its establishment as a result of the injury provoked on leaf photosynthetic apparatus. This study is aimed at evaluating the impact of chilling (40 h at 4 °C) and freezing (2 h at −1, −2 and −3 °C) on maximum leaf photosynthesis (Amax), in relation to stomatal conductance (gs) and photochemical activity. Two similar experiments were conducted in pots outdoors; treatments were performed in climate chambers at the stage of four expanded leaves per plant, and then returned outdoors. Leaf gas exchange, water status and fluorescence variables were measured at 1 and 30 days after the end of the treatments (DAT). At 1 DAT, Amax and gs were reduced up to 75% and 100% in chilling and freezing treatments, respectively. However, the intercellular CO2 concentration (Ci) showed an inverse pattern, discarding a determinant role in Amax reductions. A lower efficiency electron use for photosynthesis was detected for plants subjected to chilling and freezing stress. The potential efficiency of PSII (Fv/Fm), chlorophyll content (Chl) and relative water content (RWC) were only affected by the lowest freezing treatments, while chilling and intermediate freezing plants showed an increase of the non photochemical quenching (NPQ). Leaf death occurred in the lowest freezing treatments, while several residual effects on Amax, gs and electron transport rate (ETR) were also observed at 30 DAT in the survival plants. This work sheds light on the determinant processes involved in the depletion of photosynthesis by chilling and freezing injuries, revealing that low temperatures have persistent and detrimental effects on J. curcas crop establishment.
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Inexpensive thermoregulated boxes for use in studies of seed germination are described. Each box is heated by a built-in resistance and is controlled by a thermostat. The boxes can be calibrated for constant or alternating regimes.... more
Inexpensive thermoregulated boxes for use in studies of seed germination are described. Each box is heated by a built-in resistance and is controlled by a thermostat. The boxes can be calibrated for constant or alternating regimes. Construction specifications are provided. Some performance tests showed that these boxes are suitable for carrying out germination studies
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ABSTRACT Plant root aeration relies on aerenchyma and barrier formation in outer cortex influencing the radial oxygen loss (ROL) from roots towards the rhizosphere. Plant species display large variation in strategies for both responses.... more
ABSTRACT Plant root aeration relies on aerenchyma and barrier formation in outer cortex influencing the radial oxygen loss (ROL) from roots towards the rhizosphere. Plant species display large variation in strategies for both responses. We investigated the impacts of root-zone hypoxia on aerenchyma formation and development of ROL apoplastic barriers in the outer cortex as a function of root tissue age, using three lowland grassland species, each with alternative aerenchyma structure. All species increased root aerenchyma and continued with root elongation after imposing hypoxia. However, ROL barrier development differed: (i) Rumex crispus displayed only partial barrier to ROL evidenced at older tissue ages, (ii) Cyperus eragrostis initiated a tighter barrier to ROL following exposure to hypoxia in tissues older than 3 days , and (iii) Paspalidium geminatum demonstrated highly effective inhibition of ROL under aerated and hypoxic conditions at all tissue ages related to constitutive tight apoplastic barriers in outer cortex. So, hypoxic conditions affected root elongation and tightness of apoplastic barriers depending on species. The physiological implications of the different ROL responses among species in relation to the differential formation of barriers are discussed.
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... The use of microcosms has proved to be a powerful empirical tool to examine, for instance, the effect of abiotic constraints (Weiher and Keddy 1995) and extreme events (see MacGillivray et al. 1995, Flynn et al. 1995) on plant... more
... The use of microcosms has proved to be a powerful empirical tool to examine, for instance, the effect of abiotic constraints (Weiher and Keddy 1995) and extreme events (see MacGillivray et al. 1995, Flynn et al. 1995) on plant community structure. ...
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Strong fluctuations are exhibited by populations of the perennial herb Ambrosia tenuifolia in the grasslands of the Salado basin (Province of Buenos Aires, Argentina), an area frequently enduring prolonged floods. Flooding causes the... more
Strong fluctuations are exhibited by populations of the perennial herb Ambrosia tenuifolia in the grasslands of the Salado basin (Province of Buenos Aires, Argentina), an area frequently enduring prolonged floods. Flooding causes the death of most dicotyledon plants of the ...
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Page 1. Flooding induces secondary dormancy in Setaria parviflora seeds Federico PO Mollard*, Pedro Insausti and Rodolfo A. Sánchez IFEVA-CONICET, Facultad de Agronomıa, UBA, Av. San Martın 4453, C1417DSE, Buenos Aires, Argentina Abstract... more
Page 1. Flooding induces secondary dormancy in Setaria parviflora seeds Federico PO Mollard*, Pedro Insausti and Rodolfo A. Sánchez IFEVA-CONICET, Facultad de Agronomıa, UBA, Av. San Martın 4453, C1417DSE, Buenos Aires, Argentina Abstract ...
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Research Interests: Soil, Water, Biomass, Plant Biology, Ecology, and 9 moreLotus, Porosity, Air, IT Strategy, Floods, Plant Roots, Solubility, CARBOHYDRATES, and Plant Leaves
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Page 1. Flooding induces secondary dormancy in Setaria parviflora seeds Federico PO Mollard*, Pedro Insausti and Rodolfo A. Sánchez IFEVA-CONICET, Facultad de Agronomıa, UBA, Av. San Martın 4453, C1417DSE, Buenos Aires, Argentina Abstract... more
Page 1. Flooding induces secondary dormancy in Setaria parviflora seeds Federico PO Mollard*, Pedro Insausti and Rodolfo A. Sánchez IFEVA-CONICET, Facultad de Agronomıa, UBA, Av. San Martın 4453, C1417DSE, Buenos Aires, Argentina Abstract ...