The effect of salinity on the growth rate of Zizania palustris in controlled and natural settings

Abstract

We compared the growth rate of wild rice, Zizania Palustris, in varying concentrations of road salt—0 mg/L, 100 mg/L, 500 mg/L, 1000 mg/L, 3000 mg/L, and 5000 mg/L. Then, we conducted two experiments, one in a controlled environment using a growth chamber, and the other outside. In the growth chamber, we had six replicates of each salt solution, giving us a total of 36 Petri dishes, with two seeds in each replicate. In the outdoor experiment, we set up three tubs and each contained nine plastic Solo® cups to grow the wild rice in. We put approximately 222 grams of sand from the shore of Douglas Lake in each cup and distributed the six solutions randomly throughout each tub. The remaining three cups contained only sand to make sure weight was distributed evenly and the cups had an equal amount of space within the tubs. We weighed the seeds in the growth chamber on day 5 of the experiment, and then weighed them again on day 7, along with the root and shoot of each plant. On day 10, we did the same for the plants outside. Using a significance level of 0.05 for both environments, we analyzed the seeds from the growth chamber and used a linear regression model. On both day 5 and day 7 in the growth chamber, weights of the wild rice plants confirmed that there was a negative relationship between salinity level and seed growth (R2 = 0.960 for day 5 and 0.964 for day 7, both with a p-value of 0.00). However, for the outdoor experiment, the linear regression test was not significant (R2 = 0.428, p-value = 0.159). Both experiments showed significance when ANOVA tests were conducted (growth chamber p-value = 0.010, outside = 0.020) and we concluded that higher salt concentrations have a negative effect on the growth of wild rice. Using a Dunnett test we found this was true for the plants in the growth chamber, particularly at the higher levels of 3000 mg/L and 5000 mg/L.