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

1. 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

2. 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

3. 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

4. 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

5. Plant pot Emitter Water source Capillary pressure concept • No pumping needed • Low installation cost • Undemanding operator expertise and system maintenance H Schematic representation of the capillary irrigation system for container grown plants

6. 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

7. 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

8. 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.

9. System Design PES membrane on the disc Perforated acrylic discs Disc fixed into the plastic cup Plexiglass tube connected to the cup

10. System setup Initial setup As growth progressed...

11. 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

12. 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

13. Results and Discussion PLANT HEIGHT LEAF NUMBER

14. LEAF AREA

15. 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

16. 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 < 0.05.

17. 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 < 0.05.

18. 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

19. 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

20. 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)

21. Questions?