Transcript Click Here for PPT of above poster

Abstract
The Dry Future of Corn: Exogenous Applications
of Salicylic Acid
Drought has been considered one of the most acute abiotic
stresses presently affecting agriculture (Khan, et al.). Salicylic
acid is a naturally occurring phenolic compound that plays an
important role in the response to abiotic stress, specifically
drought (Miura). However, the impact of SA depends on the
concentration, mode of application, and state of the plants.
This study examines the optimal mode of exogenous
applications of salicylic acid on corn plants to alleviate the
negative effects of drought. Modes of application include the
foliar spray and seed pre-treatment. In this study,
concentrations of 5 and 10 mM SA were used for the foliar
spray and concentrations of 0.5 and 0.1 mM SA were used
for the pretreatment solutions. It is predicted that the foliar
spray with 5 mM of salicylic acid will best alleviate the
negative effects of drought on Z. Mays.
Cindy Wang and Michelle Xing
Methods
All Z. Mays seeds are first sterilized with 1% sodium hypochlorite.
Foliar Spray
● 25 seeds planted in 5 pots per
treatment group
Background
● 25 seeds planted in 5 pots.
● Inducing Drought Stress
○ 20 days without water
Leaves placed in
separate vials with 10
mL of 95% ethanol
Leaves cut
into small
pieces
Mixture is boiled and
then strained into
separate falcon tubes.
Relative Water Content
Leaves are soaked in
water for 24 hrs, then the
turgid weight of the leaves
is measured.
Fresh weight
is measured.
Seed Pretreatment
● Two forms of the pretreatment method were used: the
seed priming method and the presoaking method to test
the effects of different reagents (water, NaCl, PEG, and
GA) on Z. mays plants.
● Results: the presoaking method is recommended to
harvest better benefits in the plants compared to the
priming method (Yu Tian, et al.).
Hypothesis
The maize plants treated with the 5 mM of SA by foliar spray will display
the best results because lower concentrations have shown to work
better than higher concentration (Manzoor).
Leaves are
oven dried for
72 hrs at 70
degrees C.
Absorbancy of leaf extract
measured at 648 and 664 nm
with spectrophotometer.
Relative Water Content calculated
using equation:
RWC = fresh weight-dry weight/turgid
weight-dry weight * 100
Shoot Length in inches
Relative Water Content percent
Results
Figure 3: The effect of Salicylic Acid (SA) on shoot length.
Error bars represent +/- one standard deviation of the mean.
PT 0.1 = Pretreatment 0.1 mM SA; PT 0.5 = Pretreatment 0.5
mM SA; Foliar 5 = Foliar Spray 5 mM SA; Foliar 10 = Foliar
Spray 10 mM SA. (n = 21-24 per group)
Shoot Weight in Grams
Foliar Spray
● Application of three concentrations of salicylic acid (5mM,
10mM and 15mM) were tested to ameliorate the effects of
salinity and drought stress, two related abiotic stresses
(Manzoor, et al.).
● Significant role of SA in drought and salinity tolerance.
Lower concentrations were seen to be more effective.
I. Overall, the pretreatment groups were found to improve
plant growth and development.
A. The difference between the percentages of relative
water content of PT 0.1 and control was 4.5 and
between PT 0.5 and control was 1.06.
B. On the other hand, Fol 10 and control group were the
same and Fol 5 actually did worse with a difference of
0.5 in RWC %.
C. In both chlorophyll a and b, the pretreatment groups did
way better than the foliar spray groups (differences = 3
with PT –0.5; 5 with 0.1)
II. The morphological parameters,shoot length and shoot
weight, showed a better alleviation of drought stress in the
pretreatment and foliar groups than the control group.
III.There was a decline in shoot length and shoot weight for
Fol 5 mM compared to the others.
A. It had the lowest values between all groups: 5.1386
inches shoot length and 0.33741 grams for shoot
weight
IV.Difference of means between PT .1 and Fol. 5 was
0.20188 grams as a significant increase in shoot weight
observed
V. Conflicting data with past results:
A. Manzoor found that lower concentration of SA, namely
5 mM, was more effective.
B. This study found that 10 mM fol is better than 5 mM.
Chlorophyll Extraction
–
Figure 2: Representation NO, salicylic acid (SA), and jasmonic acid (JA) interactions
during plant responses to biotic challenges.
● 25 seeds soaked in SA solution for
24 hours and planted in 5 pots, per
treatment group.
**
**
**
Figure 5: The effect of Salicylic Acid (SA) on shoot weight.
Error bars represent +/- one standard deviation of the mean.
There is significance (P<0.05) between groups PT 0.1 and Fol
5; PT 0.1 and Control. (n = 21-24 per group)
Figure 4: The effect of Salicylic Acid (SA) on relative water
content (RWC). Error bars represent +/- one standard deviation
of the mean. Group PT 0.1 had the smallest P values when
compared to each of the other groups. (n = 4 per group)
Chlorophyll Concentration percent
● Regulation of stomatal guard cells is an adaptive
mechanism that helps plants withstand pathogenic infection
and weather conditions like drought. When pathogens enter
through stomata, endogenous SA are increased to induce
systemic acquired resistance. Salicylic acid induces ROS
production which helps regulate homeostatic processes.
● SA response genes turn on plant defenses against drought
stress and pathogens.
SA)
● Thinned to 3 seedlings per pot
● Keep soil HYDRATED for 31
days
● Inducing Drought Stress
○ 20 days without water
○ Plants sprayed with
SA solution at 10 day
intervals
Figure 2: Model that shows loop
between SA and ROS (reactive
oxygen species) in response to
stress.
Pre-treatment (.1 and .5 mM
Control
(5 and 10 mM SA(salicylic acid))
Discussion
Figure 7: Living conditions for plants. 16 hours daylight and 8 hours of
darkness cycle.
Conclusion
I. Goals
A. Find the method of exogenous application of Salicylic
Acid that would be most beneficial for maize plants
undergoing drought stress, a prevalent problem today.
B. Pretreatment with 0.1 mM SA was the most effective
treatment
1. Reasoning: smallest concentration of SA.
2. The spraying of SA directly onto the leaves in the
foliar spray treatment may have inhibited some
chemical processes resulting in decreased levels of
chlorophyll.
II. Future research: SA operates in a variable manner,
promoting factors like growth, but inhibiting other plant
functions. As seen in this project, the relative water
content and chlorophyll content did not improve
significantly compared to the control group.
A. Use SA in conjunction with another compound to more
effectively ameliorate the effect of drought stress.
Bibliography
Figure 6: The effect of Salicylic Acid (SA) on chlorophyll a and
b content. Error bars represent +/- one standard deviation of
the mean. Chlorophyll a had the most significance (P= .077). (n
= 4 per group)
Idrees, M., Naeem, M., Khan, M. N., Aftab, T., Khan, M., & Moinuddin, K. (2011). Alleviation of
Salt Stress in Lemongrass by Salicylic Acid. Springer-Verlag, 249, 709-720.
Khan, M., Fatma, M., Per, T. S., Anjum, N. A., Khan, N. A. (2015). Salicylic Acid-Induced Abiotic
Stress Tolerance and Underlying Mechanisms in Plants. Frontiers in Plant Science, 6, 462.
Manzoor, K., Ilyas, N., Batool, N., Ahmad B., & Arshad M. (2015). Effect of Salicylic Acid on the
Growth and Physiological Characteristics of Maize under Stress Conditions. The Chemical
Society of Pakistan, 37, 588-593.
Premachandra G. S., Saneoka, H., Fujita K., & Ogata, S. (1993). Water Stress and Potassium
Fertilization in Field Grown Maize {Zea mays L.): Effects on Leaf Water Relations and Leaf
Rolling. J. Agronomy & Crop Science, 170, 195-201.
Tian, Y., Guan, B., Zhou, D., Yu, J., Li, G., & Lou, Y. (2014). Responses of Seed Germination,
Seedling Growth, and Seed Yield Traits to Seed Pretreatment in Maize (Zea mays L.). The
Scientific World Journal.