Tracer studies in the coffee plant (Coffea arabica L.)

Resumo

Due to the great importance of coffee to the Brazilian economy, a good deal of the work carried out in the "Laboratório de Isótopos", E. E. A. "Luiz de Queiroz", Piracicaba, S. Paulo, Brazil, was dedicated to the study of some problems involving that plant. The first one was designed to verify a few aspects of the control of zinc deficiency which is common in many types of soils in Brazil. An experiment conducted in nutrient solution showed that the leaf absorption of the radiozinc was eight times as high as the root uptake; the lower surface of the leaves is particularly suited for this kind of absorption. Among the heavy metal micronutrients, only iron did not affect the absorption of the radiozinc; manganese, copper, and molybdenum brought about a decrease of fifty per cent in total uptake. In another pot experiment in which two soils typical of the coffee growing regions were used, namely, a sandy soil called "arenito de Bauru" and a heavy one, "terra roxa", only O.l and 0.2 per cent of the activity supplied to the roots was recovered", respectively. This indicates that under field conditions the farmer should not attempt to correct zinc deficiency by applying zinc salts to the soil: leaf sprays should be used wherever necessary. In order to find out the most suitable way to supply phosphatic fertilizers to the coffee plant, under normal farm conditions, an experiment with tagged superphosphate was carried out with the following methods of distribution of this material: (1) topdressed in a circular area around the trees; (2) placed in the bottom of a 15 cm deep furrow made around the plant; (3) placed in a semicircular furrow, as in the previous treatment; (4) sprayed directly to the leaves. It was verified that in the first case, circa 10 per cent of the phosphorus in the leaves came from the superphosphate; for the other treatments, the results ware, respectively: 2.4, 1.7, and 38.0 per cent. It is interesting to mention that the first and the last methods of distribution were those less used by the farmers; now they are being introduced in many coffee plantations. In a previous trial it was demonstrated that urea sprays were an adequate way to correct nitrogen deficiency under field conditions. An experiment was then set up in which urea-C14 was used to study the metabolism of this fertilizer in coffee leaves. In was verified that in a 9 hours period circa 95 per cent of the urea supplied to the leaves had been absorbed. The distribution of the nitrogen of the urea was followed by standard chemical procedures. On the other hand the fate of the carbonic moiety was studied with the aid of the radiochromatographic technique. Thus, the incorporation of C14 in aminoacids, sugars and organic acids was ascertained. Data obtained in this work gave a definite support to the idea that in coffee leaves, as in a few other higher plants, a mechanism similar to the urea cycle of animals does exist.


Tracer studies in the coffee plant (Coffea arabica L.)* * Supported by the Rockefeller Foundation and by Brazilian National Research Council.

E. Malavolta; >L. Neptune Menard; J. D. P. Arzolla; O. J. Crocomo; H. P. Haag; W. L. Lott

E. S. A. "Luiz de Queiroz", University of S. Paulo Piracicaba, S. Paulo, Brazil

SUMMARY

Due to the great importance of coffee to the Brazilian economy, a good deal of the work carried out in the "Laboratório de Isótopos", E. E. A. "Luiz de Queiroz", Piracicaba, S. Paulo, Brazil, was dedicated to the study of some problems involving that plant.

The first one was designed to verify a few aspects of the control of zinc deficiency which is common in many types of soils in Brazil. An experiment conducted in nutrient solution showed that the leaf absorption of the radiozinc was eight times as high as the root uptake; the lower surface of the leaves is particularly suited for this kind of absorption. Among the heavy metal micronutrients, only iron did not affect the absorption of the radiozinc; manganese, copper, and molybdenum brought about a decrease of fifty per cent in total uptake. In another pot experiment in which two soils typical of the coffee growing regions were used, namely, a sandy soil called "arenito de Bauru" and a heavy one, "terra roxa", only O.l and 0.2 per cent of the activity supplied to the roots was recovered", respectively. This indicates that under field conditions the farmer should not attempt to correct zinc deficiency by applying zinc salts to the soil: leaf sprays should be used wherever necessary.

In order to find out the most suitable way to supply phosphatic fertilizers to the coffee plant, under normal farm conditions, an experiment with tagged superphosphate was carried out with the following methods of distribution of this material: (1) topdressed in a circular area around the trees; (2) placed in the bottom of a 15 cm deep furrow made around the plant; (3) placed in a semicircular furrow, as in the previous treatment; (4) sprayed directly to the leaves. It was verified that in the first case, circa 10 per cent of the phosphorus in the leaves came from the superphosphate; for the other treatments, the results ware, respectively: 2.4, 1.7, and 38.0 per cent. It is interesting to mention that the first and the last methods of distribution were those less used by the farmers; now they are being introduced in many coffee plantations.

In a previous trial it was demonstrated that urea sprays were an adequate way to correct nitrogen deficiency under field conditions. An experiment was then set up in which urea-C14 was used to study the metabolism of this fertilizer in coffee leaves. In was verified that in a 9 hours period circa 95 per cent of the urea supplied to the leaves had been absorbed. The distribution of the nitrogen of the urea was followed by standard chemical procedures. On the other hand the fate of the carbonic moiety was studied with the aid of the radiochromatographic technique. Thus, the incorporation of C14 in aminoacids, sugars and organic acids was ascertained. Data obtained in this work gave a definite support to the idea that in coffee leaves, as in a few other higher plants, a mechanism similar to the urea cycle of animals does exist.

Full text available only in PDF format.

Texto completo disponível apenas em PDF.

BIBLIOGRAFIA

  • BIDDULPH, O. 1953 - Translocation of radioactive mineral nutrients in plants. A conference on the use of isotopes in plant and animal research, TID-5098: 48-58.
  • BONNET, J. A. and A. R. RIERA. 1954 - Radioactive studies with p32 in tropical soils and crops of Puerto Rico. Trans. Vth Internatl. Congr. Soil Sci. (Leopoldville) 2: 369-375.
  • CAIN, J. Ç. -956 - Absorption and metabolism of urea by leaves of coffee, cacao and banana. Proc Am. Soc. Hort. Sci. 67: 279-286.
  • EPSTEIN, E. and C. E. HAGEN. 1952 - A kinetic study of the absorption of alkali cations by barley rocts. Plant Physiol. 27: 457-474.
  • FRANCO, C. M. and H. C. MENDES. 1953 - Deficiência de microelementos em cafeeiro (Nota preliminar). Boi. Super. Serv. Café 28: 19-22.
  • KASTING, R. and C. C. DELWICHE. 1958 - Ornithine, citrulline, and arginine metabolism in watermelon seedlings. Plant Physiol. 33: 350-354.
  • MALAVOLTA, E. and D. PELLEGRINO. 1954 - Estudos sôbre a distribuição do radiozinco no tomateiro (Lycopersidum esculentum) An. E. S. A. "Luiz de Queiroz" 11: 78-84.
  • MALAVOLTA, E., J. D. P. ARZOLLA and H. P. HAAG, 1957 - Absorption of urea sprays by coffee leaves under field conditions. Plant Physiol. 32 (Suppl.): XIV.
  • MALAVOLTA, E., J. D. P. ARZOLLA, H. P. HAAG, T. COURY e O. J. CROCOMO. 1958 - Nota sôbre a aplicação da uréia em pulverização no cafeeiro. Rev. Agric. 32: 223-226.
  • OVERSTREET, R. and L. JAÇOBSON. 1952 - Mechanism of ion absorption by roots. Ann. Rev. Plant Physiol. 3: 189-206.

  • *
    Supported by the Rockefeller Foundation and by Brazilian National Research Council.

Datas de Publicação

  • Publicação nesta coleção
    10 Set 2012
  • Data do Fascículo
    1959
Universidade de São Paulo, Escola Superior de Agricultura Av.Páduas Dias, 11, C.P 9 / Piracicaba - São Paulo, Brasil, tel. (019)3429-4486, (019)3429-4401 - Piracicaba - SP - Brazil
E-mail: scientia@esalq.usp.br