Fast Plant Lab - Walp 1 Introduction Background: Brassica...

Walp 1
Introduction
Background:
Brassica rapa (B. rapa) is a form of wild mustard from the plant family Cruciferae which
also includes mustards, radishes, and cabbages. These crops are known for their nutritional
value. Dr. Paul Williams was the person to work with these ‘fast plants’ and select characteristics
that were most useful in a classroom or laboratory setting. He bred the plants for many years,
always selecting for the shortest flowering time, the most rapid seed maturations, and plants with
no seed dormancy required. He selected for their ability to produce seeds even at high planting
density, and also a small plant size. Another selection made was made to ensure their ability to
grow under continuous florescent light and in a standard potting soil. The Fast Plants that we
used had a life cycle of 5 weeks. This time period is 1/5 of the time of the life cycle of the
original plants the Fast Plants were bred from. Our section dealt with varying the concentration
of NaCl. By doing this we are performing a single variable experiment and are able to examine
the effect chemical stress has on our Fast Plants. Salinity has a negative effect on plant growth
when too much gathers near the roots. When there is excess salt in the root zone, water uptake is
hindered and thus plant growth is hindered.
Hypothesis:
We expect that extreme NaCl concentration, 320 mM NaCl, will not be beneficial to the
growth of our fast plants and will result in shorter stem height. The more moderate
concentrations of NaCl, 0 mM, 40 mM, 80 mM, and 160 mM, will promote the healthiest plants
with longer stems and more leaves.

Walp 2
Null Hypothesis:
We expect that extreme NaCl concentration, 320 mM NaCl, will have no effect on the
growth of our fast plants where height or leaf count is concerned. The more moderate
concentrations of NaCl, 0 mM, 40 mM, 80 mM, and 160 mM, will also have no marked effect on
our plants and we will see no change in height or leave count.
Materials and Method
For this experiment we used a total of 15 fast plant seeds, 5 salsa cups, vermiculite,
Peter’s solution, peat moss, and five concentrations of NaCl: [0], [40], [80], [160], and [320]. We
began by preparing 5 of the salsa cups for planting. We poked a small hole in the bottom of each
cup and then placed a wick inside the hole. Three pebbles were added to the bottom of the cup
and on top of that the potting mix was added. We then moistened the soil with the nutrient
solution until it dripped freeing from the wick. Three seeds were added to each of the five cups
and then covered with a small amount of vermiculite. Each cup was then watered again and then
placed back on the tray in the reservoir. Each pot was labeled with the set concentration for easy