NOTA
Tarcizo Toledo Carnaúba; Altino Aldo Ortolani
SUMMARY
An injury has been observed on trunks of grafted young avocado trees in plantations of tropical regions of the State of São Paulo, with typical characteristics of sun burn. The beginning of the lesion is always noted on the side of the trunk exposed toward north, close to the grafting side. Under conditions of controlled temperature, 40 plants were tested by means of a G.E. infra-red industrial reflector. Tests were carried out with temperature at 35, 40, 42, 44, 45, 48 and 50°C, with exposure of 120 minutes, all of them with 5 repetitions. The trunk temperature was taken with the help of thermocouples copper-constantan, n.° 30, and of a potentiometer of Leeds and Northrup. The results obtained in the laboratory showed that the harm was lethal in the treatments at 45°C and that the levels of resistance of the stock and the graft differ. The former resisted to temperatures up to 45°C and were only harmed at the temperature of 48°C.
Comparing these data obtained in the laboratory, with the climatic and microclimatic conditions of the regions where this fruit tree is being cultivated, the harm caused can be accounted for by the over-heating of the microclimatic layer near the surface of the soil, a fact which is normally observed in several avocado producing countries.
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Recebida para publicação a 8 de junho de 1966.
Lesão do colo de mudas de abacateiro por temperatura elevada
Datas de Publicação
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Publicação nesta coleção
24 Mar 2009 -
Data do Fascículo
1966
