The Effect of Saline Irrigation
on Capsicum Fruit Quality
Barry Dungan
Plant and Environmental Sciences
Chile Products
•Chile is an versatile crop for New Mexico
•Chile produces two commercially valuable
secondary metabolites:
Carotenoids extracted for oleoresin
production.
Color
Capsaicinoids extracted for spices,
medicinal creams, and pepper spray.
Pungency
New Mexico Agriculture Issues
• Quality and abundance of water is an issue in New
Mexico
– semi-arid climate
– Agriculture crops
– Drought periods
• Approximately ¾ of the groundwater in New Mexico
is saline (Reynolds, 1962)
• This study will compare the metabolite production in
three chile cultivars irrigated with three different
levels of saline water.
Objectives
•Determine the effect of saline irrigation on fruit
quality traits in Capsicum species
•Characterize the expression of genes on the
capsaicinoid and carotenoid biosynthetic pathway
Materials and Methods
Takanotsume
NuMex Garnet
Early Jalapeno
• Germinated in a growth chamber, transplanted to the
greenhouse
– 2 gallon pots
– Metro Mix 360 soil
Materials and Methods
• Saline water treatments
– Control (potable water)
– 750 PPM/TDS
– 1500 PPM/TDS
• 1.5 L every other day
• ~2 month period
• Fruit/Flower development monitored by
tagging
Salt Profile
• Water collected from Geothermal well AC19373
near the NMSU golf course.
• 930 mg/L Na2SO4
• 105 mg/L KCl
• 150 mg/L MgSO4
• 489 mg/L CaCO3
• pH 6.5-6.8
Data Collection
• Upon harvest the fruit was grouped by age,
weighed.
• Half of the fruit was placed in a forced air
oven for capsaicinoid and carotenoid analysis.
• Half of the fruit was placed at -80° for RNA
analysis.
Metabolite Extraction
• Capsaicinoids:
– 1g dry material sonicated in isopropanol 30
minutes, vortexed
• Carotenoids:
– 2g dry material was sonicated in isopropanol 30
minutes
– Saponified using Methanolic Potassium Hydroxide
UPLC Chromatogram
Ultra Pressure Liquid Chromatography was used to identify 5 carotenoids
Peak A
Peak B
Peak C
Peak D
Peak E
Capsanthin
Capsorubin
Zeaxanthin
β-Cryptoxanthin
β-Carotene
HPLC Chromatogram
A
B
High Pressure Liquid Chromatography was used to identify 2 major
capsaicinoids
Peak A
Peak B
Capsaicin
Dihydrocapsaicin
Accumulation of capsaicinoids in the fruit of
Early Jalapeno
1500000
1250000
1000000
750000
500000
250000
0
SHU
1500 PPM TDS
750 PPM TDS
Control
10 dpa
18-23 dpa 30-35 dpa 44-50 dpa
Accumulation of capsaicinoids in the fruit of
Takanotsume
700000
600000
500000
400000
300000
200000
100000
0
SHU
Control
750 PPM TDS
1500 PPM TDS
10 dpa
18-23 dpa 30-35 dpa 44-50 dpa
Total carotenoid accumulation in
Takanotsume based on developmental
80,000.00
stage
70,000.00
60,000.00
50,000.00
40,000.00
30,000.00
20,000.00
10,000.00
Peak 0.00
Area
60 DPA Control
60 DPA 1500 PPM
45 DPA Control
45 DPA 1500 PPM
Total carotenoid accumulation in Garnet based
on developmental stage
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
Peak 0
Area
60 DPA Control
60 DPA 1500 PPM
45 DPA Control 45 DPA 1500 PPM
70,000
Total carotenoid accumulation in Garnet
and Takanotsume
60,000
50,000
40,000
30,000
20,000
10,000
Peak
Area
0
Garnet Control
Garnet 1500
PPM/TDS
Takanotsume Control Takanotsume 1500
PPM/TDS
Results
• The HPLC and UPLC results show that capsaicinoid
content in Early Jalapeno was increased with salt stress.
• Their was a neutral effect in both capsaicinoid and
carotenoid accumulation in Takanotsume.
• Garnet showed a decrease in carotenoid accumulation
with salt stress.
Discussion
• Currently isolating RNA to characterize the gene
expression for the capsaicinoid and carotenoid
pathways.
• The second replication for this experiment has been
harvested and fruit analysis is underway.
• Depending on the results, other cultivars may be
tested.
– Other salt concentrations or salt ratios may be tested.
Acknowledgments
•
•
•
•
•
•
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Dr. O’Connell
Dr. Rich Richins
Erin Fitzgerald
Harvest Crew
Omar Holguin
S.W.A.T lab
Chile Pepper Institute
Reynolds, S.E., 1962, Twenty-fifth biennial report of the State Engineer of New Mexico
for the 49th and 50th fiscal years July 1, 1960, to June 30, 1962: Albuquerque, The
Valliant Company, p 193
Questions?