Climatic thresholds for concentrations of minerals and heavy metals in Argentinean soybean

Abstract

Minerals affect the nutritional, rheological, and safety features of food products. Soybeans represent a good source of minerals. The objective of this study was to evaluate the effect of the environment on the variability of mineral elements in Argentinean soybeans in field experiments. Climatic variables (maximum, mean, and minimum air temperature; solar radiation; precipitation; and potential evapotranspiration) were recorded daily during the seed filling period; soil properties were also reported. Minerals in soybeans were determined by inductively coupled plasma?mass spectrometry. Selenium was determined by hydride generation coupled to an atomic absorption spectrophotometer. Molybdenum and selenium were significantly increased (over 100%) in soybeans grown at higher soil pH with high available molybdenum. Air temperature was the climatic variable that best predicted changes in the soybean seed mineral composition. Optimum weather conditions (OWC) were defined by thresholds of the climatic variables by regression trees for desirable mineral composition. Maximum and minimum daily air temperatures during the seed filling period (30.1 and 17.1°C, respectively) were the OWC for maximizing calcium, magnesium, and manganese contents. A maximum daily air temperature over 28.0°C resulted in higher iron and cobalt levels (p < 0.001). Maximum zinc content was observed when solar radiation exceeded 18.1 MJ m−2 during seed filling (p < 0.001). Results from this study showed variation in the mineral composition of soybeans. Environmental features during the seed filling period should be considered when desired mineral composition is expected in soybean according to the end uses.