Papers by remedios romero
Journal of Plant Physiology, 2006
In order to investigate the role of Si in alleviating the deleterious effects of salinity on toma... more In order to investigate the role of Si in alleviating the deleterious effects of salinity on tomato plant growth, the tomato cultivar Moneymaker was grown with 0 or 80 mM NaCl combined with 0 and 2.5 mM Si. Plant growth parameters, salt accumulation in plant tissues and plant water relations were analysed. Si treatment did not alter salt input into the plant or salt distribution between plant organs. There were nonsignificant differences in plant water uptake, but plant water content in salinised plants supplied with Si was 40% higher than in salinised plants that were not supplied with Si. Plants treated with NaCl alone showed a reduction in plant dry weight and total plant leaf area of 55% and 58%, respectively, while the reduction in plants treated with NaCl plus Si was only 31% and 22%, respectively. Leaf turgor potential and net photosynthesis rates were 42% and 20% higher in salinised plants supplied with Si than in salinised plants that were not supplied with Si. Water use efficiency calculated from instantaneous gas exchange parameters and as the ratio between plant dry matter and plant water uptake were, respectively, 17% and 16% higher in salinised plants supplied with Si. It can be concluded that Si improves the water storage within plant tissues, which allows a higher growth rate that, in turn, contributes to salt dilution into the plant, mitigating salt toxicity effects.
Journal of the American Society for Horticultural Science, 2002
High salinity levels in irrigation water available in Mediterranean coastal areas induce a signif... more High salinity levels in irrigation water available in Mediterranean coastal areas induce a significant loss of yield in greenhouse tomato crops. This loss increases during the spring-summer growing season when high irradiance, temperature, and low humidity occur within greenhouses. This study determined whether salt-induced yield losses could be alleviated by increasing humidity by misting the greenhouse atmosphere. Plants of `Daniela' tomato (Lycopersicon esculentum Mill.), were irrigated with 0 or 50 mm NaCl added to the nutrient solution and grown under natural greenhouse conditions or under applications of fine mist every 8 min during the day. During midday hours, misting reduced greenhouse air vapor pressure deficit 1.0 to 1.5 kPa and reduced greenhouse air temperature 5 to 7-°C. Mist reduced root water uptake from the medium by 40% in nonsalinized plants and by 15% in saline conditions. Foliar concentration of Na was lower in misted-salinized plants than in nonmisted salin...
Scientia Horticulturae, 1994
Stomatal density was characterized for the abaxial and adaxial surfaces of leaves on two cultivar... more Stomatal density was characterized for the abaxial and adaxial surfaces of leaves on two cultivars, 'Maria' and 'Goldy', of gerbera (Gerberajamesonii H. Bolus ex Hook.). Determinations were performed on plants that were acclimatized in a controlled environment, and also on leaves developed at different times in the course of the growing period in a greenhouse. Differences in stomatal density were observed between cultivars, between leaf surfaces within a cultivar and between times of sampling. The mean stomatal density in 'Maria' ranged from 116 to 164 stomata mm-2, and from six to 30 stomata mm-2, respectively, for the abaxial leaf surface and for the adaxial leaf surface. In 'Goldy' stomatal density ranged from 138 to 194 mm-2 and from 12 to 36 stomata mm-2 for abaxial and adaxial surfaces, respectively. Greenhouse measurements ofstomatal conductance showed that the cultivar with the highest stomatal density ('Goldy') also had the highest conductance rate.
Plant, Cell and Environment, 1998
In citrus, the relative contributions of chloride and cations to growth disturbances induced by s... more In citrus, the relative contributions of chloride and cations to growth disturbances induced by salinity are a matter of controversy. Chloride salts (15 mol m-3 CaCl 2 , 30 mol m-3 CaCl and 30 mol m-3 KCl) reduced growth and gas exchange parameters, increased leaf damage and abscission and produced anatomical disarrangements and mineral imbalances in seedlings of sensitive Carrizo citrange (Citrus sinensis x Poncirus trifoliata) and tolerant Cleopatra mandarin (Citrus reshni). In both cultivars, Ca 2+ was more beneficial, and K + more detrimental, for growth than sodium. Photosynthesis and growth disturbances were highly correlated (P ≤ 0•001) with leaf Clbuild-up. In the sensitive genotype, Clwas also significantly correlated with several leaf anatomical disarrangements, such as increase in succulence. In comparison with sodium, both calcium and potassium increased leaf Clcontent (up to 25 and 69%, respectively). Protective calcium effects were not linked to improvement of photosynthesis, reduction of leaf anatomical disarrangements, or prevention of Cland Na + increases. It is proposed that the ameliorative effects of calcium on citrus grown under salinity are mostly related to reduction of leaf abscission. Collectively, the data suggest a cause-effect relationship between Clbuild-up and reduced growth, whereas chloride correlations with declines in photosynthesis or increases in succulence appear to be indirect.
Plant Science, 2001
Growth and water uptake both decreases when tomato plants are irrigated with saline water. To det... more Growth and water uptake both decreases when tomato plants are irrigated with saline water. To determine the relative contribution of physiological traits to these decreases plant fresh and dry weight, leaf area, leaf water (c w) and osmotic (c P) potentials, gas exchange parameters, stomatal density, leaf chlorophyll and Na content were investigated in the tomato (Lycopersicon esculentum) cultivars, Daniela and Moneymaker. Plants were grown in greenhouse, in sand culture, and irrigated with a complete nutrient solution supplied with 0 (control), 35 and 70 mM NaCl over a period of 2 months. Salinity reduced plant dry weight, height and number of leaves even at 35 mM NaCl. Leaf c w and c P decreased with salinity but leaf turgor pressures were significantly higher in salinised than in control plants which suggests that bulk tissue turgor did not limit growth under the saline conditions tested. Increasing salinity in the irrigation solution led to both morphological changes [(reduction of plant leaf area and stomatal density) and physiological changes [reduction of stomatal conductance, transpiration, and net CO 2 assimilation (A CO 2)] Plant water uptake, measured as the difference between volume of nutrient solution supplied and drainage collected, was closely related to transpiration, stomatal conductance, and stomatal density. Chlorophyll content per unit of leaf area increased with salinity. Reduction of net A CO 2 with salinity was explained in higher degree by stomatal conductance and stomatal density than by Na accumulation in the leaves. Although plant water uptake was similar for the two cultivars, Daniela transported, per unit of water uptake, more Na to the leaves than did Moneymaker. However, Daniela reduced leaf area less than did Moneymaker. Water use efficiency, calculated either as the ratio between total plant dry matter and total plant water uptake, or as the ratio between net A CO 2 and transpiration, did not change under our saline growth conditions. The contribution of the observed salt-responses to reduction in shoot water loss, plant water uptake and salt loading, while keeping water use efficiency, is discussed in relation to salt tolerance. Because some of these salt-responses take a long time to develop, growing seedlings in seedbeds with saline media could be of interest to better tolerate further salty conditions in the field or greenhouse.
Physiologia Plantarum, 2003
Previous studies on the tomato (Lycopersicon esculentum Mill.) peroxidase TPX1, including the dev... more Previous studies on the tomato (Lycopersicon esculentum Mill.) peroxidase TPX1, including the development of transgenic tomato over-expressing this gene, supported an involvement of this peroxidase in the synthesis of lignin and suberin. The transgenic plants showed a wilty phenotype at flowering, but the relationship between this role in ligno-suberization and this phenotype was not clear. In the present study a histological approach and the measurement of water-related parameters have been performed in order to obtain an insight into the origin of this phenotype. Clear differences between transgenic and non-transgenic roots were observed in the cross-sections of the basal root zones where secondary growth was evident. The diameter of the xylem vessel was diminished in the transgenic plants. Total area corresponding to xylem in the basal cross-sections decreased 3.9 fold in the transgenic roots. In addition, the radial and outer tangential walls of the exodermis cells were more ligno-suberized in transgenic than in non-transgenic plants. After fruit set, predawn and midday water potentials were lower in transgenic than in-nontransgenic plants. At midday, the stomatal conductance was also lower in the transgenic plants, 494±69 versus 594±60 mmol m À2 s À1. Root hydraulic conductances of the transgenic and non-transgenic plants were 1.4±0.38 and 3.47±0.19 g water min À1 MPa À1 , respectively. The results obtained support that the phenotype is caused by the anatomical differences found in the transgenic roots. These differences would be the cause of a increased resistance to water flow in the roots that would negatively affect the water supply to the shoot and, as a consequence, resulted in a decreased water potential in the leaves.
Physiologia Plantarum, 2009
The tos1 (tomato osmotically sensitive) mutant, isolated from an in vitro screen of root growth d... more The tos1 (tomato osmotically sensitive) mutant, isolated from an in vitro screen of root growth during osmotic stress, was less sensitive to exogenous ABA, but accumulated more ABA under osmotic stress than WT plants. We assessed growth and water relations characteristics of hydroponically grown tos1 seedlings (in the absence of osmotic stress) at low and high evaporative demands. Growth of tos1 was severely inhibited at both high and low evaporative demands. Twenty DAS, WT and tos1 genotypes had a similar leaf water and turgor potential, but mature tos1 plants (45 day old) showed a significant diurnal loss of leaf turgor, with recovery overnight. Increased evaporative demand increased turgor loss of tos1 plants. High evaporative demand at the beginning of the day decreased stomatal conductance of tos1, without diurnal recovery, thus whole plant transpiration was decreased. De-topped tos1 seedlings showed decreased root hydraulic conductance and had a 1.4-fold increase in root ABA concentration. Impaired root function of tos1 plants failed to meet transpirational water demand and resulted in shoot turgor loss, stomatal closure and growth inhibition.
Physiologia Plantarum, 2003
Previous studies on the tomato (Lycopersicon esculentum Mill.) peroxidase TPX1, including the dev... more Previous studies on the tomato (Lycopersicon esculentum Mill.) peroxidase TPX1, including the development of transgenic tomato over-expressing this gene, supported an involvement of this peroxidase in the synthesis of lignin and suberin. The transgenic plants showed a wilty phenotype at flowering, but the relationship between this role in ligno-suberization and this phenotype was not clear. In the present study a histological approach and the measurement of water-related parameters have been performed in order to obtain an insight into the origin of this phenotype. Clear differences between transgenic and non-transgenic roots were observed in the cross-sections of the basal root zones where secondary growth was evident. The diameter of the xylem vessel was diminished in the transgenic plants. Total area corresponding to xylem in the basal cross-sections decreased 3.9 fold in the transgenic roots. In addition, the radial and outer tangential walls of the exodermis cells were more ligno-suberized in transgenic than in non-transgenic plants. After fruit set, predawn and midday water potentials were lower in transgenic than in-nontransgenic plants. At midday, the stomatal conductance was also lower in the transgenic plants, 494±69 versus 594±60 mmol m À2 s À1 . Root hydraulic conductances of the transgenic and non-transgenic plants were 1.4±0.38 and 3.47±0.19 g water min À1 MPa À1 , respectively. The results obtained support that the phenotype is caused by the anatomical differences found in the transgenic roots. These differences would be the cause of a increased resistance to water flow in the roots that would negatively affect the water supply to the shoot and, as a consequence, resulted in a decreased water potential in the leaves.
Physiologia Plantarum, 2009
The tos1 (tomato osmotically sensitive) mutant, isolated from an in vitro screen of root growth d... more The tos1 (tomato osmotically sensitive) mutant, isolated from an in vitro screen of root growth during osmotic stress, was less sensitive to exogenous ABA, but accumulated more ABA under osmotic stress than WT plants. We assessed growth and water relations characteristics of hydroponically grown tos1 seedlings (in the absence of osmotic stress) at low and high evaporative demands. Growth of tos1 was severely inhibited at both high and low evaporative demands. Twenty DAS, WT and tos1 genotypes had a similar leaf water and turgor potential, but mature tos1 plants (45 day old) showed a significant diurnal loss of leaf turgor, with recovery overnight. Increased evaporative demand increased turgor loss of tos1 plants. High evaporative demand at the beginning of the day decreased stomatal conductance of tos1, without diurnal recovery, thus whole plant transpiration was decreased. De-topped tos1 seedlings showed decreased root hydraulic conductance and had a 1.4-fold increase in root ABA concentration. Impaired root function of tos1 plants failed to meet transpirational water demand and resulted in shoot turgor loss, stomatal closure and growth inhibition.
Scientia Horticulturae, 1994
Stomatal density was characterized for the abaxial and adaxial surfaces of leaves on two cultivar... more Stomatal density was characterized for the abaxial and adaxial surfaces of leaves on two cultivars, 'Maria' and 'Goldy', of gerbera (Gerberajamesonii H. Bolus ex Hook. ). Determinations were performed on plants that were acclimatized in a controlled environment, and also on leaves developed at different times in the course of the growing period in a greenhouse. Differences in stomatal density were observed between cultivars, between leaf surfaces within a cultivar and between times of sampling. The mean stomatal density in 'Maria' ranged from 116 to 164 stomata mm -2, and from six to 30 stomata mm -2, respectively, for the abaxial leaf surface and for the adaxial leaf surface. In 'Goldy' stomatal density ranged from 138 to 194 mm -2 and from 12 to 36 stomata mm -2 for abaxial and adaxial surfaces, respectively. Greenhouse measurements ofstomatal conductance showed that the cultivar with the highest stomatal density ('Goldy') also had the highest conductance rate.
Plant Science, 2001
Growth and water uptake both decreases when tomato plants are irrigated with saline water. To det... more Growth and water uptake both decreases when tomato plants are irrigated with saline water. To determine the relative contribution of physiological traits to these decreases plant fresh and dry weight, leaf area, leaf water (c w ) and osmotic (c P ) potentials, gas exchange parameters, stomatal density, leaf chlorophyll and Na content were investigated in the tomato (Lycopersicon esculentum) cultivars, Daniela and Moneymaker. Plants were grown in greenhouse, in sand culture, and irrigated with a complete nutrient solution supplied with 0 (control), 35 and 70 mM NaCl over a period of 2 months. Salinity reduced plant dry weight, height and number of leaves even at 35 mM NaCl. Leaf c w and c P decreased with salinity but leaf turgor pressures were significantly higher in salinised than in control plants which suggests that bulk tissue turgor did not limit growth under the saline conditions tested. Increasing salinity in the irrigation solution led to both morphological changes [(reduction of plant leaf area and stomatal density) and physiological changes [reduction of stomatal conductance, transpiration, and net CO 2 assimilation (A CO 2 )] Plant water uptake, measured as the difference between volume of nutrient solution supplied and drainage collected, was closely related to transpiration, stomatal conductance, and stomatal density. Chlorophyll content per unit of leaf area increased with salinity. Reduction of net A CO 2 with salinity was explained in higher degree by stomatal conductance and stomatal density than by Na accumulation in the leaves. Although plant water uptake was similar for the two cultivars, Daniela transported, per unit of water uptake, more Na to the leaves than did Moneymaker. However, Daniela reduced leaf area less than did Moneymaker. Water use efficiency, calculated either as the ratio between total plant dry matter and total plant water uptake, or as the ratio between net A CO 2 and transpiration, did not change under our saline growth conditions. The contribution of the observed salt-responses to reduction in shoot water loss, plant water uptake and salt loading, while keeping water use efficiency, is discussed in relation to salt tolerance. Because some of these salt-responses take a long time to develop, growing seedlings in seedbeds with saline media could be of interest to better tolerate further salty conditions in the field or greenhouse.
Plant Cell and Environment, 1998
In citrus, the relative contributions of chloride and cations to growth disturbances induced by s... more In citrus, the relative contributions of chloride and cations to growth disturbances induced by salinity are a matter of controversy. Chloride salts (15 mol m–3 CaCl2, 30 mol m–3 CaCl and 30 mol m–3 KCl) reduced growth and gas exchange parameters, increased leaf damage and abscission and produced anatomical disarrangements and mineral imbalances in seedlings of sensitive Carrizo citrange (Citrus sinensis x Poncirus trifoliata) and tolerant Cleopatra mandarin (Citrus reshni). In both cultivars, Ca2+ was more beneficial, and K+ more detrimental, for growth than sodium. Photosynthesis and growth disturbances were highly correlated (P≤ 0·001) with leaf Cl– build-up. In the sensitive genotype, Cl– was also significantly correlated with several leaf anatomical disarrangements, such as increase in succulence. In comparison with sodium, both calcium and potassium increased leaf Cl– content (up to 25 and 69%, respectively). Protective calcium effects were not linked to improvement of photosynthesis, reduction of leaf anatomical disarrangements, or prevention of Cl– and Na+ increases. It is proposed that the ameliorative effects of calcium on citrus grown under salinity are mostly related to reduction of leaf abscission. Collectively, the data suggest a cause–effect relationship between Cl– build-up and reduced growth, whereas chloride correlations with declines in photosynthesis or increases in succulence appear to be indirect.
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Papers by remedios romero