<i>LiCl Calc</i>: tools to use lithium chloride solutions to control relative humidity in seed experiments

Lithium chloride (LiCl) solutions are used in seed science for creating controlled relative humidity (RH) environments which are critical for studies on seed longevity, storage behaviour and moisture content analysis. While Hay et al. (2008) remains the foundational reference for the use of LiCl solutions in seed research, applying the information can be complex at times. Automating the calculation necessary to put this information into practice has the potential to simplify preparation for experiments requiring modified RH environments while enhancing reproducibility. In this research note, we present a refitting of the Boltzmann sigmoidal equation based on Hay et al . (2008) data to predict RH values based on LiCl concentration. This equation is then used in a series of R functions available through the R package seedTools and as an online Shiny app, LiCl Calc , that incorporates these functions into an intuitive interface, enabling researchers without R programming expertise to easily create and adjust LiCl solutions. Both the functions and the app support four tasks: preparing new solutions for specific RH values, modifying existing solutions to achieve new RH’s, predict the resulting RH when mixing two LiCl solutions and estimating RH when LiCl concentration is known. The functions are presented through practical examples.