Efecto de la temperatura del suelo y su oscilación sobre el crecimiento y la acumulación de nutrimentos en la parte aérea del café

Abstract

An apparatus was developed to control soil temperature inside experimental pots. The temperature was controlled in such a way as to imitate closely the continuous variation of the temperature of the top layers of the soil in the field during the daily 24 hour period. Starting from a predetermined lower level in the morning, the temperature was increased slowly to a maximum predetermined level just after noon. After staying about two hours at this higher level the temperature decreased slowly until reaching again the morning temperature. This daily cycle was maintained during the experiment. The lower and higher temperatures and the rate of their increase and decrease can be adjusted within wide limits. This equipment was used to study the influence of the soil temperature and its oscillation on the coffee plant growth. The temperature of 33°C in the root system, for a period of about two hours daily, resulted in a small decrease in the weight of the aerial parts and a pronounced decrease in the weight of the root system, but did not result in a noticeable decrease in the height of the plants in relation to those kept at a constant 23°C Under similar conditions the maximum. temperature of 38°C for a period of about two hours caused a pronounced decrease in the height of the plants and in their top and root weight. At the constant temperature of 33°C in the root system the height of the plants and the weight of their tops and roots were drastically reduced. There is evidence showing that the reduction of the growth of the coffee plants at the higher temperatures tested is due to a lack of translocation of the absorbed phosphorus from the roots to the aerial parts.