INFLUENCE OF CITRUS LEPROSIS ON THE MINERAL COMPOSITION OF Citrus sinensis LEAVES

N. de L. Nogueira J.C.V. Rodrigues C.P. Cabral H.S. Prates About the authors

Abstracts

Citrus leprosis is the main viral disease affecting citrus in Brazil. Viral diseases can affect the mineral composition of citrus leaves, inducing mineral deficiencies. The aim of this work was to verify the influence of citrus leprosis on the mineral composition of citrus leaves, cultivar Pera. Orange seedlings were grown in pots containing sterile soil, and kept under greenhouse conditions. When plants had 15 to 20 leaves, they were infested with the mite Brevipalpus phoenicis, the leprosis vector, collected from infected citrus plants. Other plants were not infested, and were used as the control. Ninety days after infestation, all the infested plants presented leprosis lesions. The six upper leaves of each plant were collected and the determination of macro and micro-elements was performed. Leaves from the infected plants showed lower levels of N and higher levels of Ca, S and Fe, as compared to the control (= 0.05). Both treatments presented similar levels of P, K, Mg, Cu,Mn, Zn and B.

citrus; leprosis; mineral composition; leaf analysis


A leprose dos citros é uma das principais doenças de citros no Brasil. As doenças causadas por vírus podem afetar a composição mineral de folhas de citros, induzindo deficiências minerais. Este trabalho teve como objetivo analisar a influência da leprose dos citros na composição mineral de folhas de citros, cultivar Pera. Seedlings de laranja foram crescidos em vasos contendo solo estéril e mantidos em casa de vegetação. Plantas com 15 a 20 folhas foram infestadas com ácaro da espécie Brevipalpus phoenicis, vetor da leprose dos citros, provenientes de plantas de citros com sintomas da doença. Outras plantas não foram infestadas, e serviram como controle. Após noventa dias, todas as plantas infestadas apresentavam lesões de leprose. Seis folhas da parte superior de cada planta foram coletadas para determinação dos teores de macro e micronutrientes. As folhas das plantas infectadas apresentaram níveis mais baixos de N e mais elevados de Ca, S e Fe relativamente ao controle (= 0.05). Os dois tratamentos apresentaram níveis similares de P, K, Mg, Cu, Mn, Zn e B.

citrus; leprose; composição mineral; análise foliar


NOTA

INFLUENCE OF CITRUS LEPROSIS ON THE MINERAL COMPOSITION OF Citrus sinensis LEAVES

N. de L. NOGUEIRA1; J.C.V. RODRIGUES2,4; C.P. CABRAL1; H.S. PRATES3

1Centro de Energia Nuclear na Agricultura, C.P. 96, CEP: 13400-970 - Piracicaba, SP.

2Centro de Citricultura "Sylvio Moreira"-IAC, C.P. 4, CEP: 13490-970 - Cordeirópolis, SP.

3CATI/SAA, Campinas, SP.

4Bolsista RHAE/MCT.

ABSTRACT: Citrus leprosis is the main viral disease affecting citrus in Brazil. Viral diseases can affect the mineral composition of citrus leaves, inducing mineral deficiencies. The aim of this work was to verify the influence of citrus leprosis on the mineral composition of citrus leaves, cultivar Pera. Orange seedlings were grown in pots containing sterile soil, and kept under greenhouse conditions. When plants had 15 to 20 leaves, they were infested with the mite Brevipalpus phoenicis, the leprosis vector, collected from infected citrus plants. Other plants were not infested, and were used as the control. Ninety days after infestation, all the infested plants presented leprosis lesions. The six upper leaves of each plant were collected and the determination of macro and micro-elements was performed. Leaves from the infected plants showed lower levels of N and higher levels of Ca, S and Fe, as compared to the control (= 0.05). Both treatments presented similar levels of P, K, Mg, Cu,Mn, Zn and B.

Key Words: citrus, leprosis, mineral composition, leaf analysis

INFLUÊNCIA DA LEPROSE DOS CITRUS NA COMPOSIÇÃO MINERAL DAS FOLHAS DE Citrus sinensis

RESUMO: A leprose dos citros é uma das principais doenças de citros no Brasil. As doenças causadas por vírus podem afetar a composição mineral de folhas de citros, induzindo deficiências minerais. Este trabalho teve como objetivo analisar a influência da leprose dos citros na composição mineral de folhas de citros, cultivar Pera. Seedlings de laranja foram crescidos em vasos contendo solo estéril e mantidos em casa de vegetação. Plantas com 15 a 20 folhas foram infestadas com ácaro da espécie Brevipalpus phoenicis, vetor da leprose dos citros, provenientes de plantas de citros com sintomas da doença. Outras plantas não foram infestadas, e serviram como controle. Após noventa dias, todas as plantas infestadas apresentavam lesões de leprose. Seis folhas da parte superior de cada planta foram coletadas para determinação dos teores de macro e micronutrientes. As folhas das plantas infectadas apresentaram níveis mais baixos de N e mais elevados de Ca, S e Fe relativamente ao controle (= 0.05). Os dois tratamentos apresentaram níveis similares de P, K, Mg, Cu, Mn, Zn e B.

Descritores: citrus, leprose, composição mineral, análise foliar

INTRODUCTION

Citrus leprosis is one of the main diseases occurring in sweet orange orchards of the São Paulo State - Brazil. It is characterized by the occurrence of localized symptoms on fruits, leaves and branches, possibly induced by virus introduction during the feeding process of the vector mite, Brevipalpus phoenicis.

The development of a viral disease may interfere with the host plant metabolism and induce alterations which may affect the mineral composition of the plant. Alterations in the mineral composition of leaves of citrus from plants attacked by other viral diseases such as exocortis, xyloporosis and psorosis have been reported by Rodriguez & Gallo, 1968.

Recognizing alterations in the mineral composition due to virus infection helps to interpret leaf chemical analyses more realistically. Low mineral levels may not only be indicatives of soil deficiency, but can be a result of viral induced metabolic changes.

The objective of this work was to study the influence of citrus leprosis on the mineral composition of Citrus sinensis leaves, cv. Pera.

MATERIAL AND METHODS

Twelve sweet orange seedlings (Citrus sinensis) cv Pera were grown in pots containing one kilogram of sterile soil and kept under greenhouse conditions. When the plants had 15-20 leaves, six plants were infested with 40-50 mites (Brevipalpus phoenicis) of the citrus leprosis vector. The mites were collected from infected citrus plants which had been used in previous studies of Rodrigues, 1995. The other six plants were not infected and used as control. Ninety days after infestation, all the infested plants presented many leprosis lesions. The six upper leaves of each plant (infested and non-infested) were collected for mineral analysis of macro and micro elements, performed according to Malavolta et al. (1989).

RESULTS AND DISCUSSION

Results chemical analysis showed that the development of leprosis on the sweet orange cv. Pera is always accompanied by significant alterations in the levels of Cu, Fe, Mn and Zn (TABLE 1), which may or may not be induced by the causal agent.

Leaves collected from the infected plants presented lower levels of nitrogen and higher levels of calcium, sulphur and iron as compared to the control (a= 0,05). Both treatments presented statistically similar levels of phosphorus, potassium, magnesium, boron, copper, manganese and zinc.

Sulphur absorption by the plants is an active process and the sulphate absorption from soil by the roots is dependent of the accompanying cation. This cation can be Ca+2 which is transported passively. Calcium accumulates in plant tissues which have a higher rate of transpiration (Malavolta, 1980) indicating that the infected leaves possibly present alterations in the transpiration rates. This was observed in citrus plants infected by others viruses (Rodriguez & Inforzato, 1968).

According to Malavolta (1980) sixty percent of the total Ca and seventy five percent of Fe in the leaves are present in the chloroplasts and show structural changes due the infection caused by the leprosis virus (Kitajima et al., 1972, Rodri-gues, 1995). These results allow speculation on the effect of the disease on the photosynthetic metabo-lism, causing the degeneratAion of the photosynthetic apparatus and death of the infected tissues.

Recebido para publicação em 21.03.96

Aceito para publicação em 21.10.96

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  • MALAVOLTA, E. Elementos de nutriçăo mineral de plantas Săo Paulo: Agronômica Ceres, 1980. 254 p.
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  • RODRIGUES, J.C.V. Leprose dos citros: cíto-histopatologia, transmissibilidade e relaçăo com o vetor Brevipalpus phoenicis Geijskes (Acari: Tenuipalpldae). Piracicaba, 1995. 79p. Dissertaçäo (Mestrado) - Centro de Energia Nuclear na Agricultura, Universidade de Săo Paulo.
  • RODRIGUEZ, 0.; GALLO, J.R. The influence of viruses on the mineral composition of citrus leaves. ln: CONFERENCE OF THE INTERNATIONAL ORGANIZATION OF CITRUS VIROLOGISTS, 4., Gainesville, 1968. Proceedings... Gainesville: Florida University Press, 1968. p.307-310.
  • RODRIGUEZ, 0.; INFORZATO, R. The influence of virus on the transpiration of citrus plants. ln: CONFERENCE OF THE INTERNATIONAL ORGANIZATION OF CITRUS VIROLOGISTS, 4., Gainesville, 1968. Proceedings... Gainesville: Florida University Press, 1968. p.304-306.

Publication Dates

  • Publication in this collection
    10 Feb 1999
  • Date of issue
    May 1996

History

  • Accepted
    21 Oct 1996
  • Received
    21 Mar 1996
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