Optimizing the capillary irrigation system for better yield and quality of hot pepper

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Optimizing the capillary irrigation system for
better yield and quality of hot pepper

• V. Nalliah,
• R. Sri Ranjan Ph.D., P.Eng.
• DEPT. OF BIOSYSTEMS ENGINEERING
• UNIVERSITY OF MANITOBA
• WINNIPEG
• CANADA

CSBE/SCGAB 2008 50th Annual Conference Vancouver,
British Columbia July 13 - 16, 2008
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A need for capillary irrigation

• Water conservation is important in irrigated
  agriculture
• limited water resources
• losses during irrigation
• competition for water among the different users
• Improving the sustainability of water resources
• A potential solution is micro irrigation
• frequent water application in small flow rates
  either on or below the soil surface
• Drip, bubbler, spray jet, and subsurface
  irrigation systems

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Types of irrigation in Canada

• 49.8 sprinkler irrigation
• 23.2 travelling gun
• 13.1 drip system and
• 13.8 other irrigation systems such as flooding
  and subsurface irrigation

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Advantages of subsurface irrigation

• Lower risk of evaporation, runoff losses from the
  soil surface
• Greater savings of water, nutrient, and labor
• Fewer chances for foliage diseases
• More uniform plant growth
• Very adaptable to different soil conditions
• Gives a better chance to optimize the use of
  fertilizer and other chemical applications, and
• lower rate of weed growth

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Capillary pressure concept

• No pumping needed
• Low installation cost
• Undemanding operator expertise and system
  maintenance

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Schematic representation of the capillary
irrigation system for container grown plants
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Research in the past

• Livingston (1908) introduced the negative
  pressure concept with porous clay cups
• Richards and Loomis (1942) studied the
  performance of improved double-walled irrigator
  pots suitable for low flow rates and tension
• Kato and Tejima (1982) performed a theoretical
  analysis in subsurface irrigation on the basis of
  different negative pressures
• Lipiec et al. (1988) proposed a porous tube
  negative pressure water circulation technique
  suitable for measuring plant water uptake
  continuously under laboratory conditions

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Research in the past...

• A study on the efficiency of subsurface
  irrigation under various elevation differences by
  Jiang et al. (2004)
• tested various pressures ranging from 0.5 m
  positive pressure to 4.0 m negative pressure
• water infiltration into soil was observed up to
  2.0 m soil depth without applying any pressure to
  the system
• A soil-cooling and auto-irrigating system by Liu
  et al. (2006)
• simultaneously irrigating and cooling the soil
• used porous ceramic pipes
• electric pump was used to maintain the pressure

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Objectives

• To compare the yield and quality of hot pepper
  using capillary irrigation systems under
  different negative pressures.
• To optimize the pressure of the system for
  producing pepper under controlled environment.

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System Design
PES membrane on the disc
Perforated acrylic discs
Disc fixed into the plastic cup
Plexiglass tube connected to the cup
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System setup
As growth progressed...
Initial setup
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Treatments and Measurements

• Jalapeno hot pepper (Capsicum annuum) was grown
  in a controlled-environment
• -0.20, -0.40, -0.60 m negative pressure
  irrigation, and hand-watered treatments
• A Completely Randomized Design (four treatments
  replicated seven times)
• The four irrigation treatments received the same
  experimental conditions (light, temperature, RH)
• Measurements taken were
• Plant height, number of leaves, leaf area, water
  consumption, and plant and fruit biomass
• Hotness of pepper fruits was quantified using
  HPLC

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Determination of pepper hotness

• Capsaicinoids are responsible for hotness of
  pepper
• Capsaicinoids Capsaicin Dihydrocapsaicin
• The ground oven-dried fruits were used to extract
  the capsaicinoid using acetonitrile by heating at
  800C for 4h
• An Agilent-1100 series HPLC system with 4.6x250
  mm Eclipse XDB-C18 column was used
• Standards of capsaicin and dihydrocapsaicin were
  used to identify and quantify the concentration
  of capsaicinoid in samples

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Results and Discussion
PLANT HEIGHT
LEAF NUMBER
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LEAF AREA
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Capsaicin (CAP) and dihydrocapsaicin (DICAP)
concentration for pepper plant under -0.2 m, -0.4
m, and -0.6 m capillary pressures, and hand water
(HW) treatments
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Total water consumption, biomass yields, and WUE
of hot pepper plant
a Means in the same column followed by
different letters are significantly different
using LSD at P lt 0.05.
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Effect of two irrigation treatments on fruit
biomass, fruit size, and water use efficiency
(WUE)
a Means followed by the same letter in the
same column are not significantly different using
LSD at P lt 0.05.
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Conclusions

• Jalapeno hot pepper was able to grow well under
  capillary irrigation systems
• Continuous water supply in the system eliminated
  the need for larger soil depth to store water
• The plant height, leaf number, leaf area, and
  plant biomass were significantly higher in the
  -0.2 m and the control irrigation treatments
  compared to the -0.4 and -0.6 m treatments
• The vegetative growth parameters were not
  statistically different between -0.2 m and the
  control irrigation treatments

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Conclusions...

• The reproductive growth parameters (fruit length,
  diameter, and fruit biomass) in the -0.2 m
  capillary irrigation treatment were also
  comparable to the control treatment
• The hotness of fruits in water starved plants
  were greater than in the plants under sufficient
  water
• The -0.2 m negative pressure irrigation had
  better performance in terms of growth and yield
  parameters when compared to the manual irrigation
  while saving a considerable amount of water
• The system is simple, inexpensive, water saving,
  and reproducible with minimum labor requirements
  for container grown plants

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Acknowledgement

• Manitoba Agri-Food Research Development
  Initiative (ARDI)
• Dr. Aluko Rotimi (Dept. of Human Ecology,
  University of Manitoba)
• Ms. Amarbeer Bandari (Richardson Centre for
  Functional Foods and Nutraceuticals, University
  of Manitoba)
• Dr. R. Zakaluk (Civil Engineering Technology
  Department, Red River College, Winnipeg, Canada)

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Questions?