2. Introduction  Brassica rapa, a member of the crucifer family (such as cabbage, broccoli, and turnips), is a fast-growing mustard plant.  Discrete traits were purely genetic and should not have been affected by environmental factors.  Purple/Non-purple pigmentation  Green/Yell0w-green leaf color  Continuous traits were those that could be affected environmentally but may have had genetic bases.  Number of leaves  Number of trichomes  Number of flowers

3. Introduction (cont.)  Hypothesis:  The plants with high amounts of fertilizer will have a greater number of flowers,trichomes, and leaves because there are more nutrients to support more growth. The amount of fertilizer should not affect the pigmentation (of the plant and/or leaves) because these traits should be genetic.

4. Methods  There were four groups, half with high fertilizer containers and half with low fertilizer containers. Each group has three containers all with six Brassica seedlings.  On day 3, the discrete traits were observed.  On day 17, leaf number and trichome number were recorded.  On day 31, flower number was recorded.

5. Results  There were 52 nonpurple plants and 11 purple plants.  Green leaves:  High fertilizer: 29  Low fertilizer: 1  Yellow-Green leaves:  High fertilizer: 26  Low fertilizer: 7

6. Results (cont.)  There was an average of 5.2 leaves for the high fertilizer and an average of 4.9 leaves for the low fertilizer plants.  There was an average of 9 trichomes for the high fertilizer plants and an average of 8.9 trichomes for the low fertilizer plants.  There was an average of 2.2 flowers for the high fertilizer plants and an average of 3.3 flowers for the low fertilizer plants.

7. Figure 1. Frequency of different leaf numbers for high and low fertilized plants. Some data from the high fertilizer plants is missing. While low fertilized plants had numbers all throughout the range, high fertilized plants tended to have at least four or more leaves.

8. Figure 2. Frequency of number of trichomes in high and low fertilized plants. There was not much difference between the high and low fertilized plants in terms of trichome number. Most of them had very few hairs.

9. Figure 3. Frequency of number of flowers in high and low fertilized plants. The low fertilized plants seemed to have more blooming flowers than the high fertilized plants. Some of the high fertilizer data was missing, however.

10. Discussion  Chi-Square ( χ ^2) test was done for the green/yellow-green data.  Low fertilizer followed normal inheritance patterns.  High fertilizer plants did not.  There were more nonpurple (dominant trait) plants than purple plants, so it also followed normal inheritance.

11. Discussion (cont.)  Histograms and averages were compared for the continuous data.  The high fertilizer, as predicted, did have a slightly positive effect on the number of leaves and trichomes.  The number of flowers however, could not be explained from the amount of fertilizer placed in the cups, because the low fertilizer had more flowers (on average) than the high fertilizer plants.

12. Conclusion  The discrete traits tend to follow normal Mendelian inheritance patterns, except for the high fertilizer plants in the green versus yellow-green part.  High levels of fertilizer also tended to make the plants produce slightly more leaves and trichomes than the low levels of fertilizer.  In the number of flowers, however, there was no such trend.  Overall, high levels of fertilizer do have an slight effect on plant growth when compared to low levels of fertilizer.

13. Sources  http://www.plantingscience.org/ http://www.plantingscience.org/  http://www.fastplants.org/ http://www.fastplants.org/