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MONITORING WATER STRESS IN SOYBEANS WITH REMOTE SENSING TECHNIQUES (THEMATIC MAPPER, MULTISPECTRAL SCANNER, LANDSAT-D, INFRARED THERMOMETRY, AGRICULTURAL METEOROLOGY)
Abstract
Studies were conducting during 1982 and 1983 on two isolines of Harosoy cultivar differing in pubescence density (dense and normal) under two different water treatments (full irrigation and no irrigation) to determine the effect of moisture on agronomic parameters, canopy temperature and canopy reflectance. The major objectives of this study were: (1) to develop prediction models for estimating canopy agronomic parameters (such as leaf area) which minimize the influence of soil background but which respond in a relatively sensitive manner to crop development and (2) to determine, for the dense and normal pubescence soybeans, how the diurnal changes in insolation affect the canopy temperature and canopy reflectance characteristics in the Thematic Mapper (TM) wavebands under stressed and nonstressed conditions. Reflectance measurements in the Thematic Mapper and Multispectral Scanner wavebands were made with a Barnes Model 12-1000 Modular Multiband Radiometer (MMR) and an Exotech-100A Radiometer, respectively. Canopy temperatures were measured using a Telatemp Ag-42 infrared thermometer. The field research was conducted at the University of Nebraska Sandhills Agricultural Laboratory located in central Nebraska. Four data sets (one for bare soil and three for soybeans) were used to evaluate the performance of leaf area index prediction models. Vegetation indices for estimating leaf area are presented and evaluated. A relatively unbiased LAI prediction model using the MSS wavebands (MEX22) was based on the Kauth and Thomas greenness transformation. The best LAI prediction model using the TM wavebands was the TM greenness model (MTM23). Diurnal azimuthal canopy temperature data (measurements made from the four cardinal directions) did not show any consistent differences due to pubescence or water treatments. Canopy temperatures measured on the sides of the canopy facing towards and away from the sun showed consistent and statistically significant differences between the non-stressed and stressed soybean isolines. Diurnal canopy reflectances in all the TM wavebands showed statistically significant differences between the water treatments IIII (full irrigation) and IINN (no irrigation after the flowering stage) for both the dense and normal pubescence isolines. Under full irrigation the dense pubescent isoline reflected more than the normal isoline in all the visible TM wavebands.
Subject Area
Atmosphere|Remote sensing
Recommended Citation
RAMANA RAO, TANTRAVAHI VENKATA, "MONITORING WATER STRESS IN SOYBEANS WITH REMOTE SENSING TECHNIQUES (THEMATIC MAPPER, MULTISPECTRAL SCANNER, LANDSAT-D, INFRARED THERMOMETRY, AGRICULTURAL METEOROLOGY)" (1985). ETD collection for University of Nebraska-Lincoln. AAI8516880.
https://digitalcommons.unl.edu/dissertations/AAI8516880