The meaning of this experiment was to test the three hypotheses, when planted in a nitrogen poor soil, soybeans will grow larger if their roots are infected with the nitrogen fixing bacteria, Rhizobium. Also if planted in a nitrogen rich soil, soybeans will resist becoming infected by Rhizobium. Lastly, if planted in a nitrogen rich soil, than soybeans that do become infected by Rhizobium will grow less than those that are not infected.

The most widespread of symbiotic relationships are those between the plant family Fabaceae and the bacterial genus Rhizobium. Rhizobium bacteria enter roots through the root hairs. The first nodules are formed on the primary root. The invading bacterium induces the formation known as an infection thread. The infection thread grows through the root hair cell, and into the cells root cortex. When the thread grows through the root cortex, bacteria are released, the bacteria are then enclosed by a portion of the plasma membrane surrounding the thread. The root nodules then begin to form. Root nodules are necessary for nitrogen fixation, without them nitrogen fixation cannot occur.

The enzyme nitrogenase requires large amounts of energy to break the nitrogen bond. This energy comes from carbohydrates produced by the plant. In return for the carbohydrates expended by the plant, the plant receives nitrogen, which is fixed by the Rhizobium.

In the first step of the experiment four pots were planted with soybean seed. Four soybean seeds were inoculated with Rhizobium. This was accomplished by rolling the seeds around in dried Rhizobium. Also four seeds were kept free of Rhizobium inoculation, these were carefully kept away from any contact with the dried Rhizobium.

Soybeans infected with Rhizobium (+L) were 1.74 grams. The individual shoot weight of the plant in low nitrogen soil that was not infected with Rhizobium (-L) was much smaller at 0.4 grams.

Introduction paraphrased from; Wolfe, Andrea. Wi98, Plants, People and the Environment, 79-81

Some common words found in the essay are:
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Approximate Word count = 1436
Approximate Pages = 6 (250 words per page double spaced)