Temperatures of alfalfa, sorghum, soybean and grass as measured with leaf thermocouples and an infrared thermometer.

• Autor(a) principal: STEINMETZ, S.
• Data de Publicação: 1977
• Tipo de documento: Tese
• Idioma: fra
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1044099
• topic: Forrageira; Agroclimatologia; Ambiente; Alfafa; Gramínea; Soja; Temperatura; Sorgo

In order to obtain accurate measurements of crop tempearture it is necessary to understand how various plant, soil and meteorological factors affect crop temperature as measured with different techniques. This study was designed to evaluate the influence of several of these factors on crop temperature as measured with leaf thermocouples and an infrared thermometer. Specifically, the objectives of this study were: 1) to determine the influence of percent cover, leaf area index, planting pattern, plant morphology, etc. on the agreement of crop temperatureas measured with attached leaf thermocouples and an infrared thermometer; 2) to detect tempearature differences between different types of crops when subjects to similar environmental conditions and 3) to studythe effects of planting pattern on crop temperature. Plant, air and soil temperature were measured on plots of alfafa, grass, soybean and sorghum. Crop temperature was measured at three canopy levels with evanohm-constantan thermocouples and with an infrared thermometer. Data were collected in 1976 on July 24-25 (24 hr period), August 2-3 (27 hr period) and on August 17-18 (36 hr period) with clear or nearly clear skies. During daytime the temperature given by the infrared thermometer (TIR) showed better agreement with temperature measured by the thermocouples on sunlit leaves (TTC3) than with the temperatures given by the thermocouples at the lower canopy levels. This was particularly true for alfafa and soybean, In sorghum TIR agreed about equally (...