1. VIKAS RAMTEKE 1ST SEM. PH.D. HORTICULTURE (FRUIT SCIENCE)
ASPEE COLLEGE OF HORTICULTURE AND FORESTRY,
NAVSARI AGRICULTURE UNIVERSITY, NAVSARI, GUJARAT
DEPARTMENT OF VEGETABLE SCIENCE
ON ROLE AND MANAGEMENT OF LIGHT FOR GROWTH AND DEVELOPMENT OF VEGETABLES
VIKAS RAMTEKE
1ST SEM. PH.D. HORTICULTURE (FRUIT SCIENCE)

2. INTRODUCTION
Light is the main environmental factor affecting the growth of plant and the production of biomass.
Many metabolic processes are stimulated by light, which regulates photosynthetic activity at different levels in higher plants.
Light is the most important factor which determines quality of vegetable seedlings.
Properly cultivated seedlings should be compact, with short internodes and firm stems, large and intensively green leaves.
It guarantees the optimal development of root system after transplanting, and have an effect on the earliness, quality and quantity of the yield
VIKAS RAMTEKE (Ph.D. 1ST Sem)

3. Recently developed high-brightness light-emitting diodes (LEDs) base the future lighting technology (solid-state lighting).
The option to select specific wavelengths for targeted plant response makes LEDs more suitable for plant-based uses than many other light sources
VIKAS RAMTEKE (Ph.D. 1ST Sem)

4. SUPPLEMENT LIGHTING IN GREENDHOUSE STRUCTURES
Fluorescent lamps
These have the advantage of higher light efficiency with low heat.
This type of lamp is the most widely used for supplemental light.
It is available in a variety of colors but cool-white lamps are the most common.
High intensity (1500 ma) fluorescent tubes that require higher wattage are also commonly used to reach 2000 foot candles.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

5. These vary in size from 60 watts to 500 watts.
Incandescent lamps
These vary in size from 60 watts to 500 watts.
They are used to extend day- length in greenhouses.
The grower can vary foot- candle levels by adjusting the spacing and mounting height above the plants.
High-intensity discharge (HID) lamps
These have a long life (5000 hours or more).
With improvements made possible by the addition of sodium and metal-halides, the lamp has a high emission of light in the regions utilized by plants.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

6. Light Meters
Inexpensive light meters are available for measuring the light intensity.
The most common light meters are calibrated in foot candles (1 ft cd =10.76 lux).
Foot candles should be measured at the growing level of the plants.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

7. LED lighting Longer lamp life. Potentially smaller fixture size.
Lower lamp wattage per light-generating unit (photons), which allows for placement close to the plants due to less emitted heat
Light spectrum can be tailored by selecting specific colors to induce targeted plant responses
Prospect of higher quantum efficiency of LEDs (number of photons of photosynthetically active radiation emitted per unit of energy input)
VIKAS RAMTEKE (Ph.D. 1ST Sem)

8. EFFECT OF SHORT-WAVELENGTH LIGHT ON PLANT PHYSIOLOGY
Plants are empowered with an array of photoreceptors controlling diverse responses to light parameters, such as spectrum, intensity, direction, duration etc. These photoreceptors includes,
the red and far-red-absorbing phytochromes,
the blue and UV-A light absorbing cryptochromes,
phototropins,
and other implied photoreceptors, absorbing in UV-A and green regions.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

9. Suitably selected lighting spectrum ensures normal plant growth.
Optimization of lighting system is of especial importance for plant cultivation in greenhouses and phytotrons.
Suitably selected lighting spectrum ensures normal plant growth.
Using purposefully designed lighting spectrum enables one to regulate flowering time, the balance between growth and development processes, biomass accumulation, stem elongation.
Impact plant primary and secondary metabolism, directly associated with the food quality of vegetables.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

10. The blue light
Blue light is favorable for growth of many plants, including lettuce, spinach, wheat, radish and other.
It affects the chlorophyll formation; photosynthesis processes, stomata opening, and through cryptochrome and phytochrome system raises the photomorphogenetic response.
The blue light (450 nm) promotes dry matter production and inhibits cell elongation in stems and leaves.
The optimal flux of blue light for leafy plants is about 10-15% of the total photosyntheticaly active radiation. Moreover, the higher flux of blue light is essential for radish (for normal carbohydrate metabolism and photosynthetic assimilate transport from leaves to the storage organs, thus assuring tuber formation).
Also it has a slight effect on primary and secondary metabolite synthesis, indicating light-dependent metabolism.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

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14. The green light
Plants are green because they reflect light in this spectral region;
The green light is more efficiently transmitted through the plant body and acts as a signal to tissues not directly exposed to the light environment.
Therefore, the supplemental green light enhances biomass accumulation in the above-ground part of the plants, and also affects chlorophyll and carotenoid synthesis, thus improving the color of leaves.
Phytochromes, principally thought of as red/far-red reversible
pigments, are extremely sensitive to the entire illumination spectrum and even small variations in the spectrum initiates responses in the phytochrome system.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

15. The cyan light
There are no solid scientific evidences on the effect of the cyan light on plants.
However, it is possible, that cyan light, being close to the green region, has the same positive biological effect.
Supplemental lighting with cyan light emitting diodes (505 nm) significantly affected carbohydrate and nitrate metabolism in lettuce and slightly improved radish growth.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

16. The near UV light
Though overexposure to UV light is dangerous for the flora, small amounts of near-UV light can have beneficial effects.
In many cases, UV-light is a very important contributor for plant colors, tastes and aromas.
This is an indication of near-UV light effect on metabolic processes.
The UV light (385 nm) promotes the accumulation of phenolic compounds, enhances antioxidant activity of plant extracts, but do not have any significant effect on growth processes.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

17. Light Regulated Plant Development - Photomorphogenesis
Photomorphogenesis is defined as the ability of light to regulate plant growth and development, independent of photosynthesis.
Plant processes that appear to be photomorphogenic include internode elongation, chlorophyll development, flowering, abscission, lateral bud outgrowth, and root and shoot growth.

18. Photomorphogenesis differs from photosynthesis in several major ways:
The plant pigment responsible for light-regulated growth responses is phytochrome, not chlorophyll.
Phytochrome is a colorless pigment that is in plants in very small amounts.
Only the red (600 to 660 nm) and far red (700 to 740 nm) wavelengths of the electromagnetic spectrum appear to be important to influence the phytochrome pigments.
The wavelengths, which affect photosynthesis, are broader (400 to 700 nm) and less specific.
Photomorphogenesis requires very little light energy (light intensity) to get a growth-regulating response.
Plants generally require a greater amount of energy for photosynthesis to occur.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

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21. Using Light To Regulate Plant Growth In The Greenhouse
VIKAS RAMTEKE (Ph.D. 1ST Sem)

22. Exposing the Plants to Red and Far-red Light
Transplants of tomatoes and peppers were exposed to either End-of-Day (EOD) red (R) light or far red (FR) light, each day, for four weeks in a controlled environment room.
A treatment for comparison received no EOD R or FR light.
R and FR wavelengths were generated by filtering light from fluorescent and incandescent light sources, respectively.
After four weeks of light treatments, the transplants were then placed in large pots in the greenhouse under ambient light conditions to evaluate subsequent growth and yield.
The plants treated with EOD FR were taller and had longer total leaf lengths or larger leaf areas than plants either treated with EOD R or plants not treated with EOD light (Table 1).
For example, tomatoes treated with Far red light were 44% taller than the control, but tomatoes treated with Red light were 10% shorter than the control. EOD light during transplant production had no effect on subsequent fruit production.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

23. Table 1. Effect of End-of-Day (EOD) treatment of tomato and pepper transplants on plant height and leaf lengths or leaf area.
EOD
Tomato
Peppers
Light
Plant height
(cm)
Total Leaf
Lengths (cm)
Leaf area
(cm2)
Red
9.1
88.7
43.7
2524
Far red
14.5
115.2
51.8
3170
Control
10.1
102.0
43.8
2357
Significance * NS
VIKAS RAMTEKE (Ph.D. 1ST Sem)

24. Supplementing the Greenhouse Light Environment with Fluorescent Light
Tomato and pepper transplants grown in a glass greenhouse were treated with supplemental cool-white fluorescent light each day for one hour before sundown for a period of six weeks.
Fluorescent lamps enrich the environment with Red wavelengths, and they have been used is in previous photomorphogenesis research as a Red light source.
A control treatment consisted of no supplemental fluorescent light.
Transplants were then placed in the to evaluate subsequent growth and yield.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

25. Table 2. Tomato and pepper plant growth as affected by EOD supplemental fluorescent light prior to transplant
EOD
treatment of
transplant
Before transplanting
Height
(cm)
Leaf area
(cm2)
Tomatoes
18.6
75.3
Control
22.1
90.3
Significance *
Peppers
12.3
99.11
14.6
113.87
VIKAS RAMTEKE (Ph.D. 1ST Sem)

26. Prior to transplanting to the field, tomato and pepper plant height and leaf areas were reduced in plants treated with supplemental fluorescent light (enriched Red light) (Table 2).
Plant height was reduced by 16% compared to the control for both tomato and pepper.
Subsequently, this supplemental fluorescent light treatment reduced plant height, leaf area, and fruit weight and number prior to first fruit harvest in the field.
Total fruit production of tomatoes and peppers was not affected by fluorescent light treatment.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

27. Filtering out FR Light Using the Greenhouse Covering
As an alternative to adding more Red light, a similar effect can be obtained by removal of Far-red light, as a means to modify the R:FR ratio from the natural solar radiation.
Using liquid copper sulfate (CuSO4) filters, reduced plant height in Rosa x hybrid ‘Meirutral’ (McMahon and Kelly, 1990) and chrysanthemum (Dendranthema x grandiflorum (Ramat.) (Rajapakse and Kelly, 1992).
However, the use of CuSO4 filters is not practical in commercial horticulture due to the difficulty in handling, maintenance, as well as the phytotoxicity of CuSO4 if leakage occurred.
VIKAS RAMTEKE (Ph.D. 1ST Sem)

28. Review of Research Works

29. Athocyanin (ug/plant)
EFFECT OF LIGHT QUALITY ON MORPHOLOGY AND ANTI-OXIDANT CONTENT OF RED LEAF LETTUCE
Effect of LED quality on dry mass, anthocyanin content, and ORAC content of
21-day old lettuce cv. Outredgeous
Treatments
Dry mass (g)
Athocyanin (ug/plant)
Triphosphor fluorescence
0.70 (0.03)
26.6(3.3)
RGB: Red ( 640 nm), green (530 nm), blue (440 nm)
1.07 (0.11)
57.5(6.9)
RB: : Red ( 640 nm), blue (440 nm)
0.97(0.21)
62.2(4.0)
R : Red (640 nm)
0.83(0.13)
15.3(2.3)
Rfr : Red (640 nm), far red (730 nm)
1.21(0.06)
12.5(1.8)
Gary W. Stutte1, Sharon Edney1, Patricia Bisbee1 and Tony Skerritt2
Space Life Sciences Laboratory, Dynamac Corporation, Kennedy Space Center, FL
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35. THANK YOU….
VIKAS RAMTEKE (Ph.D. 1ST Sem)