Estrangulamento do caule do cafeeiro, causado pelo frio

Abstract

Com o objetivo de investigar se o estrangulamento do caule de cafeeiros novos, observado em alguns anos de inverno rigoroso, poderia ser conseqüência do acúmulo de camadas de ar frio nas proximidades do solo, tratou-se com temperaturas baixas a haste de plantas com cêrca de seis meses de idade. O tratamento consistiu em se fazer circular salmoura refrigerada ao redor do caule, sem, entretanto, entrar em contato com êste. Obteve-se o estrangulamento com o emprêgo de vários tratamentos que incluiam temperaturas de — 2 a — 6º C. Uma planta tratada com temperatura de — 5 a — 7º C morreu duas semanas após o tratamento. Plantas tratadas por duas horas com as temperaturas de 0 a — 2º C não exibiram estrangulamento nem qualquer outro sintoma de anormalidade.A strangulation of the stem of young coffee plants a few inches above ground has been observed in some years after a cold winter. To know if this strangulation could be caused by the action of a layer of cold air that had settled over the surface of the soil as has been suggested (1), an experiment was carried out wich consisted of circulating cold water around the stem for a certain period of time. To accomplish this a special apparatus was mode using plexiglass. To obtain temperatures below the freezing point, pre-chilled salt water was used. To avoid an injurious direct contact of brine with the stem, this was wrapped with aluminum foil which was made waterproof. Two plants subjected to temperature treatments of 0° to — 2° C survived without damage. All treatments with temperatures below — 2° C resulted in strangulation and in the case of the coldest treatment used (— 5 to — 7° C) in the death of the plant.