Browsing by Author "de Varennes, A."
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- Diagnosis and correction of iron chlorosis in fruit trees: a reviewPublication . Correia, Maribela Pestana; de Varennes, A.; Faria, E. A.Several plant species grown in calcareous soils in arid and semiarid regions are iron-deficient, a condition known as lime-induced iron chlorosis, or simply as iron chlorosis. The nutritional status of perennial plants is commonly evaluated by leaf analysis. However, there is often no correlation between iron in leaves and degree of chlorosis, and therefore leaf analysis presents serious limitations as a technique to evaluate lime-induced iron chlorosis. Recently, a technique for the early prognosis of iron chlorosis based on floral analysis was developed for fruit trees to help prevent the development of iron deficiency and avoid losses in yield and quality. Correction of iron chlorosis is commonly carried out by massive applications of synthetic iron chelates to soils. Since iron is rapidly immobilised in the soil, this treatment has to be repeated each year, representing a major part of fertilizer costs. Environmental impacts of chelates in soils have not been properly investigated, but it is known that they also result in enhanced plant uptake of metals such as copper and nickel. Alternative, more environment-friendly treatments are being evaluated. In this article we concentrate on reviewing current methods to detect and correct iron chlorosis in fruit trees.
- Differential tolerance to iron deficiency of citrus rootstocks grown in nutrient solutionPublication . Correia, Maribela Pestana; de Varennes, A.; Abadia, J.; Faria, E. A.We studied the effects of Fe deficiency on physiological parameters of citrus rootstocks grown in nutrient solution. Three 4-week old rootstocks ('Troyer' citrange - Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf., Citrus taiwanica Tan. and Shim., and 'Swingle' citrumelo - Poncirus trifoliata (L.) Raf. x Citrus paradisi Macf.) were grown in nutrient solutions with 0, 5, 10, 15 and 20 mumol Fe dm(-3). Calcium carbonate (1 g dm(-3)) was added to all solutions to mimic the natural conditions in calcareous soils. For each rootstock, shoot length, number of leaves, and root and shoot dry weights were measured at the end of experiment. Chlorophyll concentration was estimated using a portable SPAD-502 meter calibrated for each rootstock. The amount of nutrients (P, K, Mg, Ca, Fe, Zn, Mn, and Cu) was determined in shoots. Chlorophyll fluorescence parameters (F-0: basal fluorescence; F-m: maximum fluorescence; F-v = F-m - F-0: variable fluorescence) were measured with a portable fluorimeter. 'Troyer' citrange rootstock was the most tolerant to Fe deficiency. These plants grew more and accumulated more chlorophyll and nutrients than the others in the presence of low levels of Fe (10 mumol Fe dm(-3)). 'Swingle' citrumelo plants needed 20 mumol Fe dm(-3) in the nutrient solution to secure adequate growth. 'Taiwanica' orange rootstock had an intermediate behaviour, but could be distinguished from 'Troyer' citrange based on fluorescence parameters, since there was a variation in the basal fluorescence in the former, whereas in 'Troyer' citrange the basal fluorescence was not affected by the supply of Fe. (C) 2004 Elsevier B.V. All rights reserved.
- Effects of fertiliser practices on the growth and quality of two table grape cultivars: 'Cardinal' and 'D. Maria'.Publication . Domingos, I.; Silva, T.; Correia, P. J.; Correia, Maribela Pestana; de Varennes, A.In this study, the different fertilliser practices of four commercial vineyards (Vitis vinifera L. cv. 'Cardinal' and cv. 'D. Maria') in southern Portugal were assessed and compared in 2002. The vineyards were established in similar soils under the same climatic conditions and additional water was supplied by drip irrigation. At harvest, the mineral composition of petioles (P, K, Mg, Ca, Fe, Cu, Zn and Mn) and quality parameters of the grapes (total soluble solids expressed as degree Brix, cluster length and weight, number of grapes, grapes weight and rachis weight) were recorded. For the 'Cardinal' cultivar, the nutritional status of the plant was correlated with growth and yield, and the greatest values for most of the parameters studied were measured at Alvisquer farm. For the 'D. Maria' cultivar, a single correlation was found between nutrient levels and growth. Shoot and cluster lengths, and grape weight were similar at all farms, though cluster weight, number of grapes and total soluble solids were smaller at Pedras than at Alvisquer or Gomeira.
- Fe deficiency induction in Poncirus trifoliata rootstock growing in nutrient solution changes its performance after transplant to soilPublication . Gama, Florinda; Saavedra, Teresa; Diaz, I.; del Carmen Campillo, M. D.; de Varennes, A.; Duarte, Amílcar; Pestana, M.; Correia, P. J.The absence of iron (Fe) in the nutrient solution induces several physiological and morphological adaptations in the roots of Poncirus trifoliata, a citrus rootstock, thereby modifying its overall nutritional status. Whether these changes are advantageous when plants are transplanted to calcareous soils needs to be assessed. To achieve this objective a two-phase experiment was established, first in nutrient solution (phase I) then in pots containing different soils (phase II). In phase I, P. trifoliata L. Raf. plants were grown in Hoagland’s solution with 120 M of Fe (Fe120 treatment) or without (Fe0 treatment). At the end of phase I (87 days), Fe-chlorotic plants had less chlorophyll in apical younger leaves, root tips were swollen and their FC-R activity was enhanced, typical responses to Fe-stress. Chlorotic plants had less Fe compared to control plants, but accumulated more Cu and Zn. In contrast the root to shoot ratio (dry weight) and the amounts of macronutrients were not affected by Fe chlorosis. In phase II, plants of both treatments were transplanted to pots containing a calcareous (C) or a non-calcareous (nC) soil resulting in four treatments: Fe0nC, Fe120nC, Fe0C and Fe120C. From the end of phase I until the end of the experiment (353 days), the calcareous soil negatively affected the overall nutritional balance in both Fe0 and Fe120 treatments. Apparently, the ability to change metal homeostasis in particular Cu, as a Fe-stress response was maintained in plants grown in non-calcareous soil. Moreover, the previous induction of physiological and morphological adaptations to Fe depletion alleviated the iron chlorosis symptoms caused by soil carbonates. These results may point to the utilization of internal stress signalling as a tool to cope with different soil conditions.
- Floral analysis as a tool to diagnose iron chlorosis in orange treesPublication . Correia, Maribela Pestana; de Varennes, A.; Goss, M. J.; Abadia, J.; Faria, E. A.A three-year field experiment was conducted in a commercial orange grove [Citrus sinensis (L.) Osb. cv. 'Valencia late' grafted on Citrange Troyer] established on a calcareous soil in the south of Portugal, to investigate if flower analysis could be used to diagnose lime-induced iron chlorosis. In April, during full bloom, flowers and leaves were collected from 20 trees. Leaf samples were again collected from the same trees in May, June, July and August. Total chlorophyll was estimated in all the leaves sampled for foliar analysis, using a SPAD-502 apparatus. Leaves and flowers were analysed for N, P, K, Ca, Mg, Fe, Zn, Mn and Cu. Principal Component Analysis was used to evaluate the variation of nutrient concentrations in flowers, and linear regressions were established between these and the chlorophyll content of leaves 90 days after full bloom. Evaluation of the best-fit equation was carried out using separate data obtained from other groves. Variation in the pattern of floral mineral composition in the flowers showed contrasts between the increase in N, P and K and that of Ca, Fe and Zn, while the concentration of Mg, Mn and Ca varied synchronously. The ratio of Mg: Zn in flowers explained about half of the variation of chlorophyll in leaves later in the season. A ratio below 100 indicated that trees would develop iron chlorosis, while with a ratio above 200 leaves would remain green. An early prognosis of iron chlorosis based on floral analysis can benefit growers, since it allows them to apply treatments in time to prevent loss of fruit yield and quality due to iron chlorosis.
- Nutrient dynamics in orange trees: the effect of soil fertilityPublication . Correia, Maribela Pestana; Correia, P. J.; Marques, H.; Domingos, I.; de Varennes, A.Lime-induced iron (Fe) chlorosis is a nutritional disorder common in calcareous soils, which may result from a low level of Fe available or adverse factors that inhibit Fe mobilization and uptake by plants. Organic-matter amendments can prevent or correct Fe chlorosis in plants but the effect of endogenous soil organic matter (SOM) on this disorder is not known. The main subject of this work was to investigate the consequence of two contrasting levels of soil fertility on the nutritional status of an orange grove [ Citrus sinensis (L.) Osb. cv. Valencia Late]. The field experiment was conducted in a commercial citrus grove using mature trees distributed in two plots with different values of SOM, phosphorus (P), and potassium (K), but with the same level of active lime. The concentration of nitrogen (N), P, K, magnesium (Mg), calcium (Ca), Fe, copper (Cu), zinc (Zn), and manganese (Mn) in young and mature leaves and flowers was evaluated. The level of Mg and the Mg/Zn ratio in flowers from both plots, although significantly different, only indicated moderate Fe chlorosis, as predicted by a previously developed model, and was consistent with the amount of chlorophyll present in the leaves. However, nutrient partitioning between leaves of contrasting age was very different. Mature leaves from trees grown in the high-fertility plot (HF) had larger concentrations of N, P, and K but lower concentrations of Ca, Fe, and Mn than did those from the low-fertility plot (LF). Young leaves from the LF had more N, P, Mg, Cu, and Mn and less Ca and Fe than did those from the HF. Flower analysis, although useful to predict Fe chlorosis, failed to detect differences in the nutritional status of plants resulting from contrasting levels of soil fertility. Furthermore, endogenous SOM had only a marginal effect on Fe chlorosis.
- Relationship between tipburn and leaf mineral composition in strawberryPublication . Palencia, P.; Martinez, F.; Ribeiro, E.; Correia, Maribela Pestana; Gama, Florinda; Saavedra, Teresa; de Varennes, A.; Correia, P. J.Malformation of emerging leaves with distortion of leaf tips, a condition known as tipburn, is frequently observed in strawberry. Calcium (Ca) deficiency has been considered the main cause of tipburn. The aim of the present study was to analyse the relationship between leaf mineral composition and the incidence of tipburn in three short-day strawberry (Fragaria x ananassa Duch.) cultivars ('Ventana', 'Camarosa' and 'Candonga') submitted to different concentrations of Ca. The studies were conducted in a hydroponic system in a greenhouse. Calcium was added as Ca(NO(3))(2) at 2 mM, 3 mM, 4 mM and 5 mM. A completely randomized block design (4 Ca concentrations x 3 cultivars) with three replications was used. Each replicate consisted of 12 plants grown in a polyethylene bag (100 cm x 18 cm x 3 cm) filled with coconut peat. Crown diameter and tipburn incidence were evaluated throughout the experimental period, and at the end of the experiment leaf mineral composition was assessed. In general, plants with larger crown diameters had a greater incidence of tipburn. The 'Candonga' cultivar had the smallest incidence of tipburn, while the 'Camarosa' and 'Ventana' cultivars were more susceptible. There was no correlation between level of Ca applied and incidence of tipburn. The incidence of tipburn was associated with foliar K:Ca and K:Mg ratios. Ratios above 3.40 for K:Mg and 1.77 for K:Ca represented a risk of more than 50% of tipburn incidence, when overall means for all cultivars and levels of Ca were used. (C) 2010 Elsevier B.V. All rights reserved.
- Response of five citrus rootstocks to iron deficiencyPublication . Pestana, M.; Correia, P. J.; David, Maria Manuela; Abadía, Anunciación; Abadía, Javier; de Varennes, A.Citrus established in calcareous soils can be affected by iron (Fe) deficiency chlorosis which limits yield and the income of the farmer. The degree of the deficiency depends on the rootstock, but their tolerance to Fe chlorosis still requires further investigation. To study physiological parameters of citrus rootstocks that could be used to evaluate tolerance to Fe deficiency, plants of Troyer citrange (Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.), Carrizo citrange, Volkamer lemon (Citrus volkameriana Ten. & Pasq.), alemow (C. macrophylla Wester) and sour orange (C. aurantium L.) were grown in nutrient solutions with 0, 5, 10, 15 or 20 μM Fe. For each rootstock, plant height, root and shoot dry weights, and concentration of Fe in the shoots and roots were measured at the end of the experiment. Chlorophyll (CHL) concentration was estimated throughout the experimental period using a portable CHL meter (SPAD-502) calibrated for each rootstock. At the end of the experiment, CHL fluorescence parameters were measured in each rootstock with a portable fluorimeter. Maximal and variable fluorescence values indicated that the photochemistry of Troyer was more affected by a low concentration of Fe in the nutrient solution than other rootstocks. To compare rootstocks, the absolute CHL concentration was converted into relative yield by employing a scaling divisor based on the maximum value of total CHL in plants without Fe deficiency symptoms. Exponential models were developed to determine the minimum Fe concentration in nutrient solution required to maintain leaf CHL at 50% of the maximum CHL concentration (IC50). Models were also developed to assess the period of time the rootstocks were able to grow under Fe-stress conditions before they reached IC50. Volkamer lemon and sour orange needed the lowest Fe concentration (between 4 and 5 M Fe) to maintain IC50, and Troyer citrange had the highes! Fe requirement (14 M Fe). C. macrophylla and Carrizo citrange required 7 and 9 M of Fe, respectively. Similarly, Volkamer lemon and sour orange rootstocks withstood more days under total Fe depletion or with a low concentration of Fe (5 M Fe in nutrient solution) until they reached IC50, compared to the other rootstocks. The approach used led to a classification of the rootstocks into three categories, regarding their tolerance to Fe chlorosis: tolerant (sour orange and Volkamer lemon), with intermediate tolerance (C. macrophylla and Carrizo citrange), and with reduced tolerance (Troyer citrange).
- 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.
- Responses of "Newhall" orange trees to iron deficiency in hydroponics: Effects on leaf chlorophyll, photosynthetic efficiency, and root ferric chelate reductase activityPublication . Correia, Maribela Pestana; David, Maria Manuela; de Varennes, A.; Abadia, J.; 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 muM iron (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 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 muM 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 muM Fe. In the absence of calcium carbonate the photosystem 11 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.