Loading...
41 results
Search Results
Now showing 1 - 10 of 41
- Exploratory analysis of the productivity of carob tree (Ceratonia siliqua) orchards conducted under dry-farming conditionsPublication . Correia, Pedro José; Pestana, MaribelaIn Southern Portugal (Algarve), the occurrence of extreme climatic events has become more limiting to agriculture and forestry productivity. Severe or moderate drought during spring, summer, and autumn is common, with major implications on yield, farmers income, and on a long-term basis, land use. Facing this scenario, farmers rely on certain crops in order to obtain a complementary revenue, as an alternative to more intensive and high-demanding farming. One of these crops is carob tree, a multipurpose and industrial fruit tree species very well adapted to dry-farming conditions and very important to the sustainability of these fragile agroecosystems. The aim of this study is to analyse the fruit productivity during 30 years in two mature carob tree orchards grown in two contrasting soils: a fertile, calcareous soil and in a non-fertile soil. Based on this exploratory analysis, the gross income of farmers obtained from fruit selling in the regional market is discussed. Moreover, the possibility of using tree carbon sequestration as an ecosystem service shall be considered as a novel alternative in these depreciated agroecosystems.
- Effects of foliar application of organic acids on strawberry plantsPublication . Saavedra, Teresa; Gama, Florinda; Rodrigues, Maria Joao; Abadía, Javier; de Varennes, Amarilis; Pestana, Maribela; Da Silva, José Paulo; Correia, Pedro JoséThe large economic costs and environmental impacts of iron-chelate treatments has led to the search for alter-native methods and compounds to control iron (Fe) deficiency chlorosis. Strawberry plants (Fragaria x ananassa) were grown in Hoagland's nutrient solution in a greenhouse with two levels of Fe: 0 and 10 mu M Fe(III)-EDDHA. After 20 days, plants growing without Fe showed typical symptoms of Fe deficiency chlorosis in young leaves. Then, the adaxial and abaxial sides of one mature or one young leaf in each plant were brushed with 10 mM malic (MA), citric (CA) or succinic (SA) acids. Eight applications were done over a two-week period. At the end of the experiment, the newly emerged (therefore untreated), young and mature leaves were sampled for nutritional and metabolomic analysis, to assess the effectiveness of treatments. Leaf regreening was monitored using a SPAD-502 apparatus, and the activity of the ferric chelate-reductase activity (FCR) was measured using root tips. Iron deficiency negatively affected biomass and leaf chlorophyll but did not increase FCR activity. Application of succinic acid alleviated the decrease in chlorophyll observed in other treatments, and the overall nutritional balance in the plant was also changed. The concentrations of two quinic acid derivatives increased under Fe deficiency and decreased in plants treated with succinic acid, and thus they are proposed as Fe stress markers. Data suggest that foliage treatments with carboxylates may be, in some cases, environmentally friendly alter-natives to Fe(III)-chelates. The importance of Fe mobilization pathways in the formulation of new fertilizers is also discussed.
- Nutrient deficiencies in carob (Ceratonia siliqua L.) grown in solution culturePublication . Correia, P. J.; Pestana, M.; Martins-Loução, M. A.The hypothesis was tested that carob (Ceratonia siliqua L.) is able to develop morphological and physiological adaptations to tolerate or at least mitigate soil nutrient deficiencies. In this work we studied the effects of N, P, Mg, Ca and Fe deficiencies on plant morphology, biomass partitioning, concentrations of chlorophyll, fluorescence and root tip ferric chelate-reductase in carob rootstocks grown in hydroponics. Young rootstock trees were grown in hydroponics with half-strength Hoagland's solution (control) or without N, P, Mg, Ca and Fe (treatments N0, P0, Mg0, Ca0 and Fe0). Nitrogen, and P deficiency affected shoot and root growth but not biomass partitioning or photosynthetic efficiency. Plants without Mg had a few large non-ramificated roots and low photosynthetic efficiency, similar to the Fe-starved plants. Root ferric chelate-reductase activity (FC-R) expressed on a fresh weight basis was higher under P and Mg deficiencies compared with control plants, but Fe0 plants had lower FC-R activity if dry weights are used. The response of carob-tree to these particular nutrients depletion may support the ecological plasticity of this species. Under natural conditions, lack of Fe and Mg in the soil is not likely to occur, but if N and P are limiting, carob growth (shoot and root dry weights) may be negatively affected. Even so, photosynthetic efficiency is maintained, and under P stress FC-R activity may increase.
- Lavandula multifida response to salinity: Growth, nutrient uptake, and physiological changesPublication . Garcia-Caparros, Pedro; Llanderal, Alfonso; Pestana, Maribela; Correia, Pedro José; Teresa Lao, MariaFern leaf lavender (Lavandula multifida L.) is a perennial shrub native to Almeria with known medicinal properties, which grows in saline soils that are increasingly present in the Mediterranean region. However, the effects of salinity on the mineral nutrition and physiology of L. multifida are unknown. In the present study, we evaluated the salt resistance of this species and compared it with other members of the Lamiaceae. Plants of L. multifida were grown in pots in a mixture of sphagnum peat-moss and Perlite, and treated with five different NaCl concentrations [10 (control), 30, 60, 100, and 200 mM NaCl] over a period of 60 d. The effects of different levels of salinity on mineral nutrient and osmolyte concentrations and on biomass were evaluated. Our results show that L. multifida plants were able to grow with 60 mM NaCl without significant biomass reduction. Na+ and Cl- were the main contributors to the osmotic potential in both roots and leaves, whereas total soluble sugars (TSS) and proline made only a small contribution. The concentrations of TSS and proline showed different trends in the different organs: in roots, both showed the highest concentrations at 60 mM NaCl, whereas in leaves TSS increased and proline decreased with increasing salt stress. To survive salinity, L. multifida plants increased salt excretion (Na+ and Cl-) by leaves at 100 and 200 mM NaCl and leaf succulence at 60, 100, and 200 mM NaCl. Excessive accumulation of Na+ and Cl- was avoided by shedding leaves. Our results indicate that L. multifida is better adapted to salinity compared to other members of the Lamiaceael, a consideration that is particularly relevant for their growth in and saline areas.
- Foliar treatments as a strategy to control iron chlorosis in orange treesPublication . Pestana, M.; Correira, P. J.; Miguel, Maria Graça; De Varennes, A.; Abadia, J.; Faria, E. D.Different foliar treatments were applied to evaluate the recovery of iron chlorosis of orange trees (Citrus sinensis (L.) Osb. cv. 'Valencia late') grown on a calcareous soil. The treatments were: Fe (II) sulphate (500 mg Fe L-1), sulphuric acid (0.5 mM H2SO4), Fe (III)-chelate (Hampiron 654 GS, 120 mg Fe L-1) and distilled water as a control. The recovery from iron chlorosis was evaluated with the SPAD-502 apparatus and the values converted to total chlorophyll concentration. The effects of treatments on the mineral composition of leaves and flowers, and the size and quality of fruits were evaluated. The residual effect of treatments was also evaluated one year later. In orange trees, the use of frequent foliar sprays with Fe was able to alleviate Fe chlorosis and prevented yield and quality losses caused by Fe chlorosis. Compared with the control, sprays of Fe (II) sulphate led to higher concentrations of chlorophyll, Fe and Zn in leaves and flowers at the end of the experimental period, and significantly improved fruit size and quality. Leaf Fe concentration increased after the sulphuric acid spray, but this treatment did not affect fruit quality parameters. The mineral composition of flowers and leaves was correlated with some fruit quality parameters obtained one year later. These results suggest that foliar sprays with Fe could help to avoid fruit quality losses caused by Fe chlorosis in citrus orchards.
- Responses of “Newhall" orange trees to iron deficiency in hydroponics: effects on leaf chlorophyll, photosynthetic efficiency, and root ferric chelate reductase activityPublication . Pestana, M.; David, Maria Manuela; de Varennes, A.; Abadía, Javier; Faria, E. A.Orange (Citrus sinensis L. Osb. cv. ‘Newhall’) plants grafted on Citrange troyer rootstock were grown in nutrient solution with 0, 5, 10 or 20 M Fe, with and without calcium carbonate. Calcium carbonate was added in order to mimic the natural conditions in calcareous soils. Leaf chlorophyll concentration was estimated every 3–4 days using the portable instrument SPAD-502 meter. Chlorophyll fluorescence parameters, photosynthetic capacity estimated from oxygen 2 evolution, leaf Fe concentrations, and root tip ferric chelate reductase activity were measured at the end of the experiment. Plants from the 0 and 5 μM Fe treatments showed leaf chlorosis and had decreased leaf chlorophyll concentrations. Leaves of plants grown in the absence of Fe in the solution had smaller rates of oxygen evolution both in the presence and absence of calcium carbonate, compared with plants grown in the presence of 10 M Fe. In the absence of calcium carbonate the photosystem II efficiency, estimated from fluorescence parameters, was similar in all treatments. A slight decrease in photosystem II efficiency was observed in plants grown without Fe and in the presence of calcium carbonate. A 2.5-fold increase in root tip ferric chelate reductase activity over the control values was found only when plants were grown with low levels of Fe and in the presence of calcium carbonate.
- Can bicarbonate enhance the performance of carob seedlings grown in nutrient solutions with different Fe concentrations?Publication . Gama, Florinda; Correia, Pedro José; Saavedra, T.; Dandlen, Susana; de Varennes, Amarilis; Nolasco, Gustavo; Pestana, MaribelaThe aim of this work was to assess the effect of bicarbonate (Bic) ion on the nutritional status and performance of carob-tree seedlings, a species that normally grows in calcareous soil without exhibiting iron chlorosis symptoms. Seedlings were previously grown in nutrient solution with a small concentration of Fe (0.5-1 mu M) to induce a moderate chlorosis. Afterwards, two experiments were established: in experiment 1, plants were grown for 21 days in the following treatments: Fe deficiency (Fe0), 0.5 mu M Fe, 5 mu M Fe, and 5 mu M Fe plus calcium carbonate (CaCO3). After assessing these results, a second experiment was conducted for 91 days, with the following treatments: Fe0, 1 mu M Fe, 40 mu M Fe and 40 mu M Fe plus CaCO3 and sodium bicarbonate (NaHCO3). Chlorophyll of young leaves, biomass and mineral composition of leaves, stems and roots were assessed in both experiments. The ferric chelate reductase root activity (FC-R) and the genetic expression of calmodulin-regulated Ca2+-ATPase pump (ACA gene) were evaluated in experiment 2. Fe-deficient plants exhibited reduced growth and enhanced macronutrients in leaves. Root micronutrient homeostasis changed as an adaptive mechanism in carob. The addition of bicarbonate did not aggravate Fe chlorosis, as leaf chlorophyll increased significantly. Root FC-R activity and ACA gene expression was not enhanced under Fe deficiency induced by bicarbonate (Fe40 + BicNa) which suggest a positive effect of bicarbonate in the metabolism of this crop. Nevertheless, small Fe concentrations (Fe1) induced a higher ACA gene expression thus indicating some stress response signalling.
- Effectiveness of different foliar iron applications to control iron chlorosis in orange trees grown on a calcareous soilPublication . Pestana, M.; Correia, P. J.; Varennes, Amarilis de; Abadía, Javier; Faria, E. A.The effectiveness on controlling Fe chlorosis in orange trees grown on calcareous soils was tested. The treatments were Fe(II) sulfate (500 mg Fe L ÿ1), sulfuric acid (0.5mM H2SO4), Fe(III)-chelate (Hampiron 654 GS, 120 mg Fe L ÿ1) and distilled water as a control. A non-ionic wetting agent was used in all treatments. The use of frequent foliar sprays alleviated Fe chlorosis in orange trees. Sprays of Fe(II) sulfate increased the concentrations of chlorophyll, Fe and zinc in leaves and improved fruit size and quality compared to fruits of control trees. Sprays of Fe(III)-chelate also increased leaf chlorophyll and Fe concentrations and improved fruit quality, but did not increase fruit size. Sprays of sulfuric acid alone slightly increased leaf chlorophyll and Fe concentrations, without improving fruit size and quality. These results suggest that foliar sprays with Fe could help to avoid yield and quality losses caused by Fe chlorosis in citrus orchards. Furthermore, these treatments could be done with relatively cheap materials such as solutions containing Fe(II) sulfate.
- Silencing of FRO1 gene affects iron homeostasis and nutrient balance in tomato plantsPublication . Gama, Florinda; Saavedra, Teresa; Dandlen, Susana; García‐Caparrós, Pedro; de Varennes, Amarilis; Nolasco, Gustavo; Correia, Pedro José; Pestana, MaribelaBackgroundIron chlorosis is an abiotic stress of worldwide importance affecting several agronomic crops. It is important to understand how plants maintain nutrient homeostasis under Fe deficiency and recovery. AimsWe used the virus-induced gene silencing (VIGS) method to elucidate the role of the FRO1 gene in tomato plants and identify the impact on regulation of the root ferric-chelate reductase (FCR) activity and nutritional homeostasis. MethodsTomato plantlets cv. "Cherry" were transferred into half-strength Hoagland's nutrient solution containing 0.5 & mu;M of Fe (Fe0.5). In phase I, two treatments were established: control (Fe0.5) plants and VIGS-0.5 plants corresponding to plants with the FRO1 gene silenced. In phase II, plants from Fe0.5 and VIGS-0.5 were transferred to new nutrient solution and then grown for a further 14 days under 0 and 10 & mu;M of Fe (as 0.5 & mu;M would not be enough for the larger plants during phase II). Therefore, four treatments were imposed: Fe0, Fe10, VIGS-0, and VIGS-10. ResultsVIGS-0.5 plants had significantly lower chlorophyll (Chl) and root FCR activity compared to the respective non-silenced plants and retained more Cu and Zn in the roots at the expense of stems (Cu) or young leaves (Zn). Iron concentration in roots and stems decreased in FRO1 gene-silenced plants, compared to control plants, but the allocation to different organs was similar in both treatments. ConclusionsThere was a partial recovery of leaf Chl in the VIGS-10 plants and a higher concentration of Fe in all organs. In contrast, the allocation of Cu to roots decreased in the VIGS-10 plants.
- Tolerance mechanisms of three potted ornamental plants grown under moderate salinityPublication . Garcia-Caparros, Pedro; Llanderal, Alfonso; Pestana, Maribela; Correia, Pedro José; Teresa Lao, MariaThe scarcity of water in the Mediterranean area has frequently led to the use of saline water in order to irrigate ornamental plants in many nurseries. However, before the large-scale use of such waters, the ways in which the plants deal with the salinity need to be evaluated. Plants of Aloe vera L. Burm, Kalanchoe blossfeldiana Poelln and Gazania splendens Lem sp. were grown in pots with a mixture of sphagnum peat moss and Perlite. In order to evaluate the effects of different levels of salinity, three treatments using different NaCl concentrations (Electrical conductivity = 2.0 (control), 4.5 and 7.5 dS m(-1)) were applied over a period of 60 days. At the end of the experiment, the growth, physiological parameters and mineral content of the roots and leaves were assessed for each salinity treatment. After 60 days of exposure to salinity, the total biomass of all species decreased similarly. The mineral composition of roots and leaves was clearly affected. Osmolytes, such as praline, played an important role in the osmotic adjustment in all species increasing in the roots and leaves at the higher ECi. Different mechanisms of the salt tolerance were triggered in each species. A vera plants showed Na+ accumulation at the root level and a decrease in succulence index of leaves. K. blossfeldiana plants shed leaves to release Na+ and G. splendens plants accumulated Cl- and Na+ at the root level, secreted salt from leaves, lost salt by shedding of old leaves and increased the succulence index of remaining leaves. We concluded that the use of saline waters is feasible for growing these ornamental plants, and G. splendens seems to be particularly well adapted to salinity, a consideration that is particularly relevant in arid saline areas. (C) 2016 Elsevier B.V. All rights reserved.