Temperature and precipitation at specific growth stages influence soybean tocopherol and lutein concentrations.

Soybean [Glycine max (L.) Merr.] is an important source of health beneficial compounds, including tocopherols and lutein. Seeds with elevated concentrations of these health beneficial compounds may be required to meet the increasing needs of the functional food market. A study was conducted for a period of 11 years in Ottawa, ON, Canada to examine the relationship between temperature and precipitation during specific growth stage intervals (GSI) and the concentration of tocopherol (toc) and lutein in the seeds at harvest. Tocopherol concentrations in soybean were most influenced by air temperature changes, while lutein concentration was more sensitive to precipitation. Heat stress via the accumulation of temperatures greater than 31°C during the mid‐vegetative to physiological maturity GSI was positively correlated (r2 = 0.94) with α‐toc concentration. Lutein concentration was negatively correlated (r2 = 0.61) with mean cumulative precipitation (cppt) during the seed development to maturation GSI. Overall, reproductive stages were more responsive to climatic variables than vegetative stages. In addition, the cultivars with higher toc or lutein concentrations were less affected by climatic variables than cultivars with lower concentrations. Climatic factors and abiotic stress during specific growth stages may have significant impact on concentrations of health beneficial compounds in mature seeds and this should be considered in the production of soybean for the functional food market. [ABSTRACT FROM AUTHOR]