Transcript The Effects of Two Levels of Salinity on Wisconsin Fast Plants

The Effects of Two Levels of Salinity on Wisconsin Fast Plants
Megan Janssen, Emily Geison, Tiffany Bertoni, Matt Zimmerman
Augustana College
Abstract
Methods
Results
Discussion
Wisconsin fast plant (Brassica rapa, Brassicaceae) seeds
were planted in three, six-celled planting containers filled with
potting soil and put beneath a continuous grow-lux light. One
week after sprouting, one container (E1) was put into a separate
tray filled with 0.5% NaCl solution, another container (E2) was
put into a separate tray filled with 1.0% NaCl solution, and the
third container was left in regular tap water. At seven day
intervals thereafter the height of all plants was recorded, and
the numbers of leaves and flowers were recorded. By week five
of recording data, the average height (mm) of the control plants
was 175.1, 88.5 in the E1 plants, and 66.4 in the E2 plants. The ttest for height of the control plants vs the height of the E1 plants
was significant (p = 0.00004). Similarly, the t-test for the control
plants vs E2 plants was highly significant (p = 0.000002). The
height of E1 plants vs E2 plants was also significant (p = 0.004).
That same week, the average number of leaves for control
plants was 4.07, for E1 plants was 1.36, and for E2 plants was
2.00. The average weight for control plants was .51g, for E1
plants was .19 g, and for E2 plants was .15g. The T-Test for
weight comparison between control and E1 was significant
(p=.00003), between control and E2 was also significant
(p=.000003), but between E1 and E2 was not significant (p=.225).
Our hypothesis that higher salinity hinders plant growth,
flower production, and leaf production was fully supported.
We infer that fast plants and other herbaceous species may have
a lower tolerance of salinity compared to that of woody plants.
A large plastic tray with a liner had three small, 6 (4x4
cm) celled planting containers placed inside. They were labeled:
Control, E1 for 0.5% NaCl solution, and E2 for 1.0% NaCl
solution. Potting soil was put into each cell making sure that the
soil was packed down. We made small, approximately 1 cm
holes in each of the cells and placed one Wisconsin Fast Plant
seed (Brassica rapa) into each of the holes. A minimum of 15
seeds were planted in each 6-celled pack. The three packs were
then placed into the large tray and set under the grow lux light.
Two cm of water was poured into the tray. The Wisconsin Fast
plants were then left under the 24 hour grow lux light for a
week with a constant temperature of 27 degrees Celsius and
with the water level maintained at 1 cm.
On week 2 the E1 and E2 packs were put into individual
plastic containers. E1 and E2 were filled with their
corresponding salt water solutions. Every week for the next 5
weeks, our group maintained all of the specialized water levels
at 1 cm. The heights of each plant were recorded every Tuesday
morning for the five weeks by measuring from the soil surface
to the top of the apical meristem. The number of leaves and
fruits of each plant were also recorded at this time. After 3
weeks, bamboo braces were added to each plant for support.
On the sixth week, we recorded the heights, number of
leaves, and number of fruits. We then cut all of the plants at the
base of the stem, as close to the soil as possible. The plants were
weighed individually. All statistical analysis were done by the
student T-test.
Figure 1 shows that the control fast plants grew taller and
faster than the plants of E1 and of E2. The first week, where all
of the plants were in the same conditions, the heights were the
same. By week 3, the control plant’s average height was 153
mm, while E1 was just 99 mm and E2 was 72 mm. Week 5’s
average height differences proved to be significant. The
difference in height between control and E1 was significant
(p=.00005), as were between control and E2 (p=.000002), and
also between E1 and E2 (p=.005). Figure 2 exhibits the average
heights of each experimental group between weeks 2 and 5. The
difference in growth over those weeks in each of the groups is
clear. The control plants grew an average of 119.6 mm over the
3 weeks while E1 plants only grew 33.3, and E2 plants only
grew 20.5 mm (Figure 2). Significant results occured when
comparing the average weights on week 5 (Figure 3). Average
weight on week 5 for control was .51 g, for E1 was .19 g, and for
E2 was .15 g. Figure 3 shows that the weight comparison
between control and E1 were significant (p=.00003), between
control and E2 were significant (p=.000003), but between E1 and
E2 was not significant at all (p=.225). Average number of leaves
on week 5 demonstrated similar results. Figure 4 shows that
with control’s average leaves at 4.07, E1’s leaves at 1.35, and
E2’s leaves at 1.23, the comparison between control and E1 was
more significant (p=.0000002) than the comparison between
control and E2 (p=.000001). E1 and E2’s average number of
leaves were not statistically significant (p=.393).
Our study of the Wisconsin Fast Plants corroborated
other scientific studies that exhibited decreased plant height
and a reduced amount of leaves in other species of plants
(Qados, 2011). Rameeh and Gerami’s (2015) experiment with
Rapeseed showing that increased level of salinity caused
decreased growth and lower seed production, agreed with our
results. The Student T-Tests indicated that the plant heights of
the Fast Plants was inhibited by increases of salinity. We found
that the difference in height was statistically significant when
comparing the means for each group, including the comparison
between experiment group 1 and experiment group 2. This
indicates that increasing amounts of salinity decreases the
amount of stem growth in the plants. The significant difference
between E1 and E2 indicates that increasing the amount of
salinity has greater inhibition on the stem growth of Fast Plants.
When comparing the plant weights of each experimental group
to the control, both E1 and E2 were significant. Although the
difference comparing plant weights between E1 and E2 was not
significant, this could be due to the fact that many plants were
already dead and had dried out.
Our study confirmed that increasing levels of salinity is
detrimental to the growth of Fast Plants. With levels of salinity
predicted to increase, this could have increasingly negative
effects on the growth of many plants, including the Fast Plant.
It is believed that there could be a 50% loss of land from this
salinization by 2050 (Baby and Jini, 2010). Further research
should be done to examine the difference in salinity tolerance of
other plants including a comparison of herbaceous plants and
woody plants. Our hypothesis that higher salinity hinders
plant growth, flower production, and leaf production was fully
supported by the results.
Introduction
Salt water makes up about 71% of the Earth’s surface, but
only a few plants thrive in it (Glenn and O’Leary, 1985). High
salinity of groundwater may not be a common problem now for
land in Illinois, but that could change. Salinization of land is
predicted to have detrimental, worldwide effects in the coming
years due to global warming. Because of this, some believe that
there will be up to 30% land loss within the next 25 years, and
possibly up to 50% by 2050 (Baby and Jini, 2010).
The genus, Brassica, includes mustard plants, cabbages,
and other cruciferous vegetables. The Wisconsin Fast Plant
(Brassica rapa) used in this experiment is a plant with
numerous subspecies including many well-known leafy
vegetables and field mustard. So, it is widely used for human
and animal consumption throughout the world. Unlike some
plants, such as smooth cordgrass (Spartina alterniflora) that
actually do better with a higher concentration of salt, the
Wisconsin Fast Plant is not accustomed to the excess NaCl
(Courtney et al., 2016). According to Serrano and colleagues
(1999), the stresses of salt water on the plants are mostly found
to be osmotic, which disrupts homeostasis of cells and the
distribution of ions. It has been found that Rapeseed plants,
closely related to Fast Plants, grown in varying levels of salinity
were found to have decreased height and lower seed
production when compared to the plants grown without
salinity (Raheem and Gerami, 2015). It was also found that in
bean plants, the higher the concentration of NaCl, the lower the
height of the plant and the lower the number of leaves were
noticed (Qados, 2011).
The present study was performed in order to determine
the effects of two salinity levels on growth characteristics of
stem, leaves, and fruit of the Wisconsin Fast Plant. We
hypothesize that the higher the percentage of salinity, the
shorter the plant height will be and the fewer fruit and leaves
will be produced.
RESEARCH POSTER PRESENTATION DESIGN © 2015
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References
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Ramo´n Serrano1, Jose M. Mulet, Gabino Rios, Jose A. Marquez,
In˜ igo F. de Larrinoa, Martin P. Leube, Iratxe Mendizabal,
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Montesinos