This document summarizes an experiment on the effects of light intensity on tissue cultures. The experiment measured light intensity from different sources using a luxmeter. It found that intensity increased with the number of fluorescent tubes used, and was highest for sunlight outside. Covering cultures with aluminum foil or newspaper reduced intensity. The discussion notes that low light is better for callus formation but cultures need sufficient light for photosynthesis. Improvements suggested include using LED lights and optimizing spacing and lighting conditions for cultures.

1. Effects of Light on Tissue Cultures
Cell & Tissue Culture
BSc (Hons) Biotechnology
University of Mauritius
Presented By:
- Ritesh Bhagea
- Rouksaar Buctowar
- Huda Nazeer
- Christabelle Cecile
- Keshavi Ghoorbin
Date: 20th
March 2014

2. Overview
● Aims and Objectives
● Introduction
● Materials and Methods
● Result
● Discussion
● Problem with varying light intensity - How varying light
intensity affects tissue cultures
● Alternatives / Improvements
● Conclusion
● References

4. ● Luxmeter: Device to measure light intensity (SI unit: lux,
Symbol: lx) per unit area.
Introduction
● Importance of light in tissue culture:
○ Type of light source will affect light
intensity.
○ Light intensity affects photosynthesis
ability: leaf anatomy, chlorophyll
formation & chloroplast differentiation
(Aitken-Christie J., et al, 1994).
○ Callus formation & growth: low light
works better for carrot callus.

5. Materials
Luxmeter
Fluorescent Tubes Incubator
Laminar Flow
Hood (covered it
with dark cloth)
Tray Aluminium Foil
Newspaper

6. Measuring light intensity using a luxmeter:
● Experiment carried out in the Biotechnology lab and outside on FoA
ground.
● Light meter placed in the middle of the work area.
● Light sensor gripped steadily and flat - pointing towards light source.
● Three readings taken for the same place.
● Lux values converted into Watt - mean and standard deviation
calculated.
Note: The range on the luxmeter was changed depending on the
environment - outside and inside - to get more exact values of lux.
Methods

7. Results
Conditions Light Intensity Means
(Watt)
A Using one fluorescent tube 0.014 ± 2.84 x 10^-3
B Using two fluorescent tubes 0.043 ± 4.12 x 10^-3
C Using three fluorescent tubes 0.056 ± 7.36 x 10^-3
D Using four fluorescent tubes 0.069 ± 5.24 x 10^-3
E In the incubator 0.000
F In dark laminar airflow 0.000
G In a tray covered with aluminium
foil
0.000028 ± 0.019 x 10^-3
H In a tray covered with newspaper 0.00012 ± 0.025 x 10^-3
I Outside in sunlight 0.86389 ± 0.042
Table 1 : Intensity of light from different sources.

8. How light intensity affects tissue cultures:
● More light = increased adaptation of leaves in terms of leaf
anatomy, chlorophyll formation & chloroplast differentiation.
● In vitro = low light = lack of grana stacking, thinner leaves,
poorly defined mesophyll with large intercellular spaces, 1
layer of palisade cells only.
● Hence, cultures cannot use light to its maximum,
photosynthesis saturates at low light levels.
● Increasing light intensity during culture would increase
photosynthesis, given all other conditions required are
present (Aitken-Christie J., et al, 1994).
● However, low light intensity, for instance the dark, is
beneficial for callus formation in carrot.
Discussion

9. ● Explants are placed in jars
that are short and have an
opaque/ metallic cap.
● This prevents light from
reaching the explant which is
carrying out photosynthesis.
● Stressful for the explant
when the jars are crammed.
Problems
Figure 1: Jars crammed unto shelf - bad
light distribution.

10. ● The lighting system
● Use of fluorescent tubes-cool
daylight/white
● 5 tubes per shelves
○ Some were flashing
(defective ones)
● Different brands: Lamptan,
Astra, Tungsram, Osram
○ Leads to different quality of
light
Problems
Figure 2: Out of 5, only 3 lamps are
working.

11. ● Osram lamps- 36W
○ Colour - Daylight
○ Luminous flux at 25 °C = 3350 lm
○ Color rendering index Ra = ≥ 80
○ Color temperature = 2700 K
○ Lifespan = 20000 hours
● Lamptan lamps
Problems

12. Use of LED lights
● Precise beam control.
● Accelerate plant growth.
● Do not generate heat hence do not heat the plants below.
● 3 times for efficient than fluorescent lamps ( LED: 20W, Fluorescent:
~58W).
● LED are used for about 12 hrs compared to fluorescent light 16hr
per day.
● Lifetime: approximately 8 years.
Overall, LED is best for raising the best plants for the least amount
of money. Commercial growers can cut their electric bills for plant
lighting roughly in half by using colored LED lighting instead of
fluorescent lighting because they essentially pay only for the light the
plants need.
Improvements

13. ● Plants use red and
blue light the most.
● Using LED of Red
and Blue colour,
○ Plants get light of
required
wavelength
○ Money is saved
● Correct ratios must
be established for
red:blue
Improvements

14. ● Transparent caps
- Allowing transparency for maximum light to enter the jars so that the
explant can carry out photosynthesis
● Spacing the culture jars
- To allow light to pass sideways
● Use of same lighting brands
- To avoid variation in quality of light
Improvements

15. ● Source of light affects light intensity.
● Increasing no. of fluorescent tubes increases light intensity.
● Light intensity outside is greatest.
● Aluminium foil is more effective at preventing light from
passing through - more opaque.
Conclusion

16. References
● http://www.hemp-technologies.com/page87/page87.html
● http://www.ehow.com/about_5452900_led-vs-fluorescent-lighting.html
● http://cipotato.org/genebank/conservation-methods/images/in-vitro-jpg
● http://www.ledinside.com/news/2011/7/illumitex_20110712
● http://www.osram.com/osram_com/index.jsp
● http://www.carnivorousplants.org/howto/SoilsWater/Lighting.LED.php
● http://www.rapidtables.com/calc/light/lux-to-watt-calculator.htm
● http://upload.wikimedia.
org/wikipedia/commons/0/09/Plant_Tissue_Culture_Lab_-
_Atlanta_Botanical_Garden.JPG

17. Thank you for your attention!