Browsing by Author "Abadia, J."
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- 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.
- 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.
- 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 . 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.
- The use of floral analysis to diagnose the nutritional status of orange treesPublication . Correia, Maribela Pestana; Correia, P. J.; de Varennes, A.; Abadia, J.; Faria, E. A.A field experiment was conducted in a commercial orange orchard (Citrus sinensis L. cv. 'Valencia late'), established on a calcareous soil in the south of Portugal, to investigate if flower analysis could be used to diagnose the nutritional status of the trees and predict fruit quality. In April 1996, during full bloom, flowers and leaves were collected from 20 trees. Leaf samples were again collected in June and August from the same trees. In February 1997 the fruits were harvested and their quality evaluated. The concentrations of phosporous (P) and magnesium (Mg) in flowers were correlated with those in leaves, and were also predictive of the chlorophyll content of leaves 60 days later. However, by 120 days after full bloom these effects were masked, possibly by a fertilizer application carried out by the fanner. The iron (Fe) concentration in flowers was correlated with chlorophyll measured either 60 or 120 days after full bloom. These parameters can therefore be used to predict the appearance of iron chlorosis. Fresh weight and diameter of fruit were related to flower P, Mg, and manganese (Mn) concentrations, while the percentage of citric acid in the fruit juice was inversely correlated with Fe flower concentrations.