Resumos
Tem sido observada ocasionalmente uma lesão no colo de cafeeiros novos ao nível do solo. .Estudos dc laboratório mostraram que o caule de cafeeiros novos foram danificados quando ao redor dêle se fêz circular água aquecida às temperaturas de 45 o 50ºC. O aquecimento da superfície do solo, compreendendo o colo de cafeeiro vegetando em laminados, com o auxílio de uma lâmpada de raios infravermelhos, resultou em lesão semelhante àquela observada nas culturas. Essa lesão apareceu em tratamentos cujas temperaturas estiveram entre 44 e 51°C. O fato dessas temperaturas serem freqüentemente observadas em solos expostos ao sol, sugere que a lesão do caule do cafeeiro, observada freqüentemente em cafèzais novos, seja conseqüência do aquecimento excessivo da superfície do solo pelos raios solares.
A collar injury of young, field coffee plants at the soil level has been observed occasionally in the summer. The location of the abnormality and the season when it appears .suggested that excessive heating of the soil surface by the sun rays could be its cause. Two experiments were then conducted in the laboratory to investigate this bypothesis. The first experiment consisted in circulating water at the desired temperature around the stem ofyoung coffee plants, using the same apparatus described in a previous paper. In a second experiment the base of the stem and the soil around it was heated by means of a G. E. 250 watts infrared industrial reflector. By changing the distance between the heat source and the plant, different temperatures at the soil surface could be obtained. The results of the first experiment showed that 4 plants out of o that were treated at 45ºC showed injury; the other 2 plants survived without damage. From 5 plants that were treated at 50ºC, 2 showed injury and 3 died shortly after the treatment. All plants subjected to the temperature treatments at 35°C and 40ºC survived without damage, while those treated at 55ºC and 60ºC, died. In the second experiment, 5 plants out of 18 that were treated at temperatures ranging from 45ºC to 51ºC showed injury similar to that observed in the field. All plants treated at temperatures below 45ºC survived without damage with the exception of one treated al 44°C which died. All treatments above 51°C resulted in the death of the plants. It has been observed in the summer that the soil surface temperatures in the field frequently reaches the 45ºC - 51ºC range or sometimes even exceeds it. The results of the present experiments strongly suggest that coffee collar injury at the soil level as observed in the field is caused by excessive sun heating of the soil surface and stem base.
Lesão do colo do cafeeiro, causada pelo calor1 1 Trabalho apresentado na "First FAO Technical Meeting on Coffee Production and Protection, Abidjan, Ivory Coast, 21-29 October 1960.
Collar injury- young coffe plants caused by heat
Coaracy M. Franco
Seção de Fisiologia, Instituto Agronômico
RESUMO
Tem sido observada ocasionalmente uma lesão no colo de cafeeiros novos ao nível do solo. .Estudos dc laboratório mostraram que o caule de cafeeiros novos foram danificados quando ao redor dêle se fêz circular água aquecida às temperaturas de 45 o 50ºC. O aquecimento da superfície do solo, compreendendo o colo de cafeeiro vegetando em laminados, com o auxílio de uma lâmpada de raios infravermelhos, resultou em lesão semelhante àquela observada nas culturas. Essa lesão apareceu em tratamentos cujas temperaturas estiveram entre 44 e 51°C.
O fato dessas temperaturas serem freqüentemente observadas em solos expostos ao sol, sugere que a lesão do caule do cafeeiro, observada freqüentemente em cafèzais novos, seja conseqüência do aquecimento excessivo da superfície do solo pelos raios solares.
SUMMARY
A collar injury of young, field coffee plants at the soil level has been observed occasionally in the summer. The location of the abnormality and the season when it appears .suggested that excessive heating of the soil surface by the sun rays could be its cause. Two experiments were then conducted in the laboratory to investigate this bypothesis.
The first experiment consisted in circulating water at the desired temperature around the stem ofyoung coffee plants, using the same apparatus described in a previous paper. In a second experiment the base of the stem and the soil around it was heated by means of a G. E. 250 watts infrared industrial reflector. By changing the distance between the heat source and the plant, different temperatures at the soil surface could be obtained.
The results of the first experiment showed that 4 plants out of o that were treated at 45ºC showed injury; the other 2 plants survived without damage. From 5 plants that were treated at 50ºC, 2 showed injury and 3 died shortly after the treatment. All plants subjected to the temperature treatments at 35°C and 40ºC survived without damage, while those treated at 55ºC and 60ºC, died.
In the second experiment, 5 plants out of 18 that were treated at temperatures ranging from 45ºC to 51ºC showed injury similar to that observed in the field. All plants treated at temperatures below 45ºC survived without damage with the exception of one treated al 44°C which died. All treatments above 51°C resulted in the death of the plants.
It has been observed in the summer that the soil surface temperatures in the field frequently reaches the 45ºC - 51ºC range or sometimes even exceeds it.
The results of the present experiments strongly suggest that coffee collar injury at the soil level as observed in the field is caused by excessive sun heating of the soil surface and stem base.
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LITERATURA CITADA
Recebido para publicação em 20 de maio de 1961
- 1. CAMARGO, A. PAES DE. ORTOLANI, ALTINO A., RODRIGUEZ. ODY [e outro]). Efeito da cobertura do terreno em laranjal sôbre as temperaturas extremas do ar. Bragantia 20: [xi]-xvii. 1961.
- 2. DAUBENMIRE, R. R. Plants and Environment. New York, John Wiley & Sons, Inc., 1950. xiii 424 p.
- 3. __________ Soil temperature versus drought as a factor determining lower altitudinal limits of trees in the Rocky Mountains. Bot. Gaz . 105(1):1-492. 1943.
- 4. FRANCO. COARCY. M. Estrangulamento do caule do cafeeiro. causado pelo frio. Bragantia 19:[515]-521. 1960.
- 5. HARTLEY, CARL. Stem lesions caused by excessive heat. J. agric. Res. 14(13):595-604. 1918.
- 6. LEVITT, J. The Hardiness of Plants. New York, Academic Press Inc., 1956. viii, 278 p.
- 7. MEDCALE, J. C. Preliminary study on mulching young coffee in Brazil. New York, IBEC Research Institute, 1956. 47 p.
- 8. RICHARDS, S. J., HAGAN, R. M. & McCALLA, T. M. Soil temperature and plant growth. In Shaw B. T., ed. Soil Physical Conditions and Plant Growth. New York, Academic Press Inc., 1952. p. [303] 480.
Datas de Publicação
-
Publicação nesta coleção
09 Mar 2010 -
Data do Fascículo
1961
Histórico
-
Recebido
20 Maio 1961
