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XIV. MODIFYING LIGHT INTENSITY. A. Supplementary Artificial Light 1. Light Intensity and Quality Quality –400-800 nanometers Intensity –100-300 mmols/sec/m.

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Presentation on theme: "XIV. MODIFYING LIGHT INTENSITY. A. Supplementary Artificial Light 1. Light Intensity and Quality Quality –400-800 nanometers Intensity –100-300 mmols/sec/m."— Presentation transcript:

1 XIV. MODIFYING LIGHT INTENSITY

2 A. Supplementary Artificial Light 1. Light Intensity and Quality Quality – nanometers Intensity – mmols/sec/m 2 – ft. cds. Distance vs. Intensity –decrease the greater the distance

3 2.Types of Lamps a. Incandescent primarily red light point source short life b. Fluorescent deficient in red? 2', 4', 8' lengths greater uniformity shadows

4 c. Combination: -fluorescent lamps -incandescent lamps complete spectrum shadows suitable for growth room

5 d. High intensity discharge (HID) Mercury vapor –not used today Metal halide –good spectrum –lower eff. than HPS & LPS

6 High Pressure Sodium –high light intensity – watt –eff. conversion of energy Low Pressure Sodium –narrow band of light –efficient conversion

7 New Lights for Greenhouses Sulfur and microwaveDiode

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9 3. Commercial Application a. Crops Roses, chrysanthemums, seedlings, lettuce, tomatoes b. Benefits timing quality less prod. time; lower cost less fuel costs increasing branching increased keeping quality roses; fewer blind shoots

10 3.Commercial Application (contu.) c. Where used northern latitudes growth rooms d. Installation/operating costs fixture + ballast $150+ fixture + installation $2.25/sq. ft. operation: $1.50/sq.ft./yr depreciation interest on money borrowed

11 3.Commercial Application (contu.) e. Management Greenhouse –HPS 400watt; spaced 10 x 10: 10 ft above plant umols/sec/m 2 ; ft.cd. Oct to Apr night & cloudy days

12 High pressure sodium light arrangement

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15 Growth room

16 20 sq. ft. 2 ft. above plants –106 umols/sec/m2: 750 ft.cd watts –200 umols/sec/m2: 1400 ft.cd watts

17 3. Commercial Application (contu.) f. Accumulated light 200 umol/sec/m 2 for 18 hrs. –equals 23 mol/day/m 2 Summer - natural light –48 mol/day/m 2 Winter - natural light –19 mol/day/m 2

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19 A. Reducing light intensity - Why - External shading compounds –Latex paint: 1 part to 8-10 parts H 2 O –Saran cloth –Internal permanent Saran cloth Aluminum strips –Internal movable

20 B. Increasing light intensity –Clean covering –White or reflective surface –Reduce shade producing items


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