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Crop-water relation and production of two soybean varieties under different water supplies

Anda, Angela, Simon, Brigitta, Soós, Gábor, Teixeira da Silva, Jaime A., Kucserka, Tamás
Theoretical and applied climatology 2019 v.137 no.1-2 pp. 1515-1528
canopy, climatic factors, crops, evapotranspiration, instrumentation, seed yield, soybeans, stress tolerance, temperature, water requirement, water stress, water supply, water use efficiency
The estimation of evapotranspiration in a canopy rather than at the plant level is of interest to crop scientists. Information about the plant-water relationship at the canopy level permits better irrigation-related estimates. In addition, there is very limited proper instrumentation to measure evapotranspiration in water-stressed crops in trials under field conditions. The aim of this study was to estimate the evapotranspiration rates, canopy temperatures, Tc, crop water stress index (CWSI), and production of two soybean varieties using three water supply levels (unlimited water, 50% of water requirement in evapotranspirometers, and rainfed conditions). To date, there are no studies that have attempted to estimate the amount of water loss in stressed field-grown crops while operating converted evapotranspirometers. For each 0.1 increase in CWSI above 0.2, seed yield decreased by 434.1 ± 28.8 g m⁻². Mean CWSI and Tc data were inversely related to crop water use efficiency (WUE). WUE and CWSI showed a quadratic relationship, and the economic limit of CWSI was 0.62. Tc and CWSI could serve as indicators for selecting soybean varieties with different levels of stress tolerance. However, due to the short observation period in this study, results might be site-specific and should not be extrapolated to locations with completely different climatic conditions.