The results refuted our original prediction that the water from the enclosure would result in poorer growth of duckweed due to lower levels of phosphorus. The water from within the enclosure, which had 0.005 micrograms per liter of phosphorus, yielded better growth than the water from the lake, which had 0.091 micrograms per liter (see Fig. 3). If, according to the results of the experiment, phosphorus is such a significant factor in plant growth, then our prediction should have been correct. This leads us to conclude that there are other factors playing some important role in plant growth that we did not measure.
The only major differences between the various water groups used in this experiment occur with the high phosphorus group. After 20 days, the high phosphorus group had at least 15 times more total fronds then the, second highest group, the enclosure (see Fig. 1). The high phosphorus group grew at a significantly more rapid pace than the other groups (see Fig. 2). With the high phosphorus group so disproportionately high, either the initial conditions of the experiment were flawed or phosphorus has an unexpectedly powerful effect on plant growth. The difference between the enclosure group and the Lake Wingra group were relatively scant (with a difference of 1.3 fronds), compared to the high phosphorus group.
With the high phosphorus group aside, a comparison between the low phosphorus group (with an average of 7.6 fronds), the Lake Wingra group (with an average of 8.3 fronds) and the enclosure group (with an average of 9.6 fronds) shows that the amount of phosphorus in the enclosure and Lake Wingra groups is low.
If we were to continue this experiment we would try even higher levels of fertilizer to determine at which point the duckweed could not reproduce within it. This would show just how resilient the duckweed is and if it could withstand a drastic change in the watershed. It would also be noteworthy to see what data could be produced from a longitudinal study, to observe long-time growth patterns.
We could also reattempt the experiment in a different time of the year and try using a different chemical for comparison; so that we might isolate what other factors made the enclosure water a better environment for plant growth.