This investigation explores the effects of temperature on root nodulation and other plant growth factors in soy bean plants. Vegetative development such as node appearance rate increases as temperatures rise to the species’ optimum level, in which the maximum temperature for growth in C3 plants is 25 °C. (Hatfield, 2015). We hypothesized that soy bean plants would produce more nodules in 25°C than 35°C, rationalizing the Q10 theory which states that a 10 degree temperature change produces measureable effects in biological and chemical metabolic systems. This idea becomes worthy of experiment when looking at how increasing temperature affects plant health and productivity in response to Earth’s climbing temperatures. We utilized two growth chambers at 25 and 35 °C and grew 72 soy bean plants in each chamber for 3 weeks, expecting a 60% germination rate. We then uprooted the plants and collected and analyzed data on the numbers of root nodules, shoot and root height and weight ratios, wet and dry mass, and nodule diameter. Our results yielded a significant difference in number and size of root nodules, with soy bean plants grown in 25°C greatly outperforming those in 35°C. Comparatively, plants grown in 35°C had a much larger root and shoot height, representing the effects of energy expenditure placed elsewhere instead of nodulation.
O’Neill, Brooke and Kawachi, Katherine, "The Effect of Temperature on Root Nodulation and Growth in Glycine max" (2016). Pepperdine University, Featured Research. Paper 193.