Soil Temperature Simulator for Seed Germination Studies

Conventional laboratory equipment used in seed germination research provides only constant and alternating temperature. The temperature of the soil in the seed bed is hardly ever constant or alternating in the same manner, but fluctuates constantly. In order to simulate the fluctuation of soil temperature that occurs in the field, a soil temperature simulator (STS) was designed, built, and evaluated. Plastic crispers containing soil in which seed are to be planted can be partially submerged in a rectangular tank into which water can be placed to a depth of 10 cm. Temperature of the water can be adjusted by heating and refrigeration systems under the control of a variable input programmer system. Maximum capabilities of the STS are: (i) maximum temperature drop 4 °C/h, (ii) maximum temperature rise 7.5 °C/h, and (iii) maximum temperature gradient within the unit 1.0 °C. The STS is capable of simulating fluctuations in soil temperature within a range of 4 to 40 °C and is particularly suited for the study of seed imbibitional chilling injury. Journal no. J-7253