The Effect of Saline Irrigation on Capsicum Fruit Quality

Barry DunganPlant and Environmental Sciences

Carotenoids extracted for oleoresin production.

Capsaicinoids extracted for spices, medicinal creams, and pepper spray.

Color Pungency

Chile Products• Chile is an versatile crop for New Mexico• Chile produces two commercially valuable

secondary metabolites:

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

Takanotsume NuMex Garnet Early Jalapeno

Materials and Methods

• Germinated in a growth chamber, transplanted to the greenhouse – 2 gallon pots– Metro Mix 360 soil

• 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

Materials and Methods

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 ECapsanthin Capsorubin Zeaxanthin β-Cryptoxanthin β-Carotene

HPLC Chromatogram

High Pressure Liquid Chromatography was used to identify 2 major capsaicinoids

Peak A Peak BCapsaicin Dihydrocapsaicin

B

A

Accumulation of capsaicinoids in the fruit of Early Jalapeno

10 dpa 18-23 dpa 30-35 dpa 44-50 dpa0

250000500000750000

100000012500001500000 1500 PPM TDS

750 PPM TDS

Control

SHU

Accumulation of capsaicinoids in the fruit of Takanotsume

10 dpa 18-23 dpa 30-35 dpa 44-50 dpa0

100000200000300000400000500000600000700000

Control

750 PPM TDS

1500 PPM TDS

SHU

60 DPA Control 60 DPA 1500 PPM 45 DPA Control 45 DPA 1500 PPM 0.00

10,000.00

20,000.00

30,000.00

40,000.00

50,000.00

60,000.00

70,000.00

80,000.00

Total carotenoid accumulation in Takanotsume based on developmental stage

PeakArea

60 DPA Control 60 DPA 1500 PPM

45 DPA Control 45 DPA 1500 PPM

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

Total carotenoid accumulation in Garnet based on developmental stage

PeakArea

Total carotenoid accumulation in Garnet and Takanotsume

Garnet

Contro

l

Garnet

1500

P

PM/TDS

Takan

otsum

e Con

trol

Takan

otsum

e 150

0 PPM/T

DS0

20,00040,00060,000

Peak Area

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 • 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?