transpiration in plants , introduction, historical background, definition and types , rate of transpiration , materials, methedology and working plans , observation and result , discussion and conclusion .

1. MEASURING THE RATE OF TRANSPIRATION
SUBMITTED BY MAYITRAYEE DAS
GUIDED BY SIR. PRIYAJEET SINHA
KARANJIA
AUTONOMOUS
COLLEGE

2. CONTENTS:-
 1. INTRODUCTION
 2. HISTORICAL BACKGROUND
 3. DEFINATION AND TYPES
 4. RATE OF TRANSPIRATION IN DIFFERENT
PLANTS
 5. MATERIALS, METHEDOLOGY AND
WORKING PLANS
 6. OBSERVATION OR RESULTS
 7. STATISTICAL HYPOTHESIS
 8. DISCUSSION AND CONCLUSION

3. INTRODUCTION:-
 This experiment was performed to see the differing rate of
transpiration and the opening and closing of stomata on plant
leaves between certain conditions. Different variables are used
to test how the stomata would react to each condition (wind,
heat, light) and be measured through water loss . An increased
amount of water loss would signal that the stomata remained
open longer and lost more water therefore supporting higher
rates of transpiration.

4. Historical background:-
Transpiration was first worked out by Stephen Hales (17
September 1677 – 4 January 1761), an English clergyman. He
proved what is still believed, that the evaporation of water
molecules from leaves is the main force pulling the water column
up from its origin in the root.
CONT….

5. Historical background:-
 Leaf surfaces are dotted with openings called stomata, which act
rather like pores. In most plants there are more on the
undersides of the leaves than on the top. The stomata are
bordered by guard cells that open and close the pore.
Transpiration happens when the guard cells open the stomata.
This lets oxygen and water vapour flow out, and carbon dioxide
flow in. The carbon dioxide is used in photosynthesis, and the
oxygen is produced by photosynthesis.

6. Definition and types :-
The process of loss of water in the form of vapours from the
aerial portion of the living plant is called transpiration.
TYPES –
 Based on the plant parts or structure involved , tarnspiration is of 3
types;
 Stomatal transpiration:- It is the transpiration that occurs through
the stomata. The epidermis of the leaves and green stems have
numerous stomata. These are responsible for about 80-90% of the
total water tarnspired. This is also known as foliar tarnspiration.
 Cuticular transpiration :- water vapours also lost directly from the
outer walls of epidermal cells through the cuticle. Cuticle is a wax like
layer of cutin that covers the epidermis of leaves and stems. Cuticular
transpiration accounts for about 10% of the total amount of

7. TRANSPIRATION:-

8. DEFINITIONS AND TYPES:-
 Lenticular transpiration:- lenticels are small
openings in the cork of the woody stems, twigs and
fruits. Water vapours are lost through these
openings. The amount of water vapours lost
through lenticels is usually significant. However, in
deciduous trees, which shed their leaves during
autumn , lenticular transpiration can be significant.

9. Cuticular transpiration :-

10. RATE OF TRANSPIRATION :-
Plants regulate the rate of transpiration by controlling the size of the
stomatal apertures. The rate of transpiration is also influenced by the
evaporative demand of the atmosphere surrounding the leaf such as
boundary layer conductance, humidity, temperature, wind and
incident sunlight. Soil water supply and soil temperature can influence
stomatal opening, and thus transpiration rate. The amount of water lost
by a plant also depends on its size and the amount of water absorbed
at the roots. Transpiration accounts for most of the water loss by a
plant by the leaves and young stems. Transpiration serves to
evaporatively cool plants, as the evaporating water carries away heat
energy due to its large latent heat of vaporization of 2260 kj per lit.

11. Lenticular transpiration :-

12. Stomatal transpiration :-

13. ENVIRONMENTALFACTOR THAT EFFECT RATE OF
TRANSPIRATION:-
 Light: Stomata are triggered to open in light so plants transpire more
rapidly in the presence of light than in the dark.
 Temperature: Plants transpire more rapidly at higher
temperatures because water evaporates more rapidly as the
temperature rises.
 Humidity: Humidity is expressed as the percentage of water vapour
present in the atmosphere. The higher the relative humidity of the
outside atmosphere, the lower the rate of transpiration.
 Wind: When there is no breeze, the air surrounding a leaf surface
becomes increasingly humid, thus decreasing the rate of transpiration.
The increase in the wind velocity increases the rate of transpiration by
removing the humidity from the leaf surface.

14. MATERIALS, METHEDOLOGYANDWORKINGPLANS :-
 Materials :-
 4 plastic bags were taken
 4 approx. 1 foot long string were taken
 4 Coleus plant cuttings were taken
 1 wind fan was taken
 1 heat lamp was taken
 1 scale was taken.
 Methodology and working plans:-
 Acquire 4 coleus cuttings.
 Cut off any flowers/buds on the cuttings.
 Place each of the cuttings in their own plastic bag with the top wrapped
tightly around the stem of the cuttings and tied in place with a string .
 Mass each cutting (with the plastic bag ).
 Place one cutting in a controlled environment (near window )
CONT…..

15. MATERIALS, METHEDOLOGY ANDWORKING
PLANS :-
 Place a separate cutting under a heat lamp
 Place a separate cutting next to a constant fan
 Place a separate cutting under increased light
sources
 Wait 24 hours.
 Mass each cutting separately
 Place each cutting in their respective places
again.
 Wait another 24 hour.
 Mass each cutting separately .
 Repeat steps 1-13 for multiple trials.

16. OBSERVATION:-
PLANT CONTROL WIND HEAT LIGHT
Group-1 0.0446 0.0722 0.1002 0.0596
Group-2 0.0509 0.0836 0.1065 0.0522
Group-3 0.1001 0.0939 0.1406 0.0222
Group-4 0.0617 0.0555 0.1040 0.0661
Group-5 0.0404 0.0940 0.0760 0.0638
Average 0.0595 0.0798 0.1055 0.0528
T- test None 0.0810 0.0076 0.3140

17. STATISTICAL HYPOTHESIS :-
 Null hypothesis / T-test:-
 If a Coleus plant is placed besides a source of constant wind then
there will be no differences(value of 0.0810 is not less than 0.5).
Null hypothesis is not rejected.
 If a Coleus plant is placed under a heat lamp, then there will be no
difference (value of 0.0076 is less than 0.5). Null hypothesis is
rejected.
 If a coleus plant is placed under a direct light, then there will be no
difference (value of 0.3140 is not less than 0.5) Null hypothesis is
not rejected.

18. DISCUSSIONANDCONCLUSION :-
 Rates of transpiration were measured on the amount of water lost by the plants divided by the surface
area of leaves. The more water lost would imply that
 stomata were open longer and more transpiration was occurring. After running a T-Test
 for each average value of the variables, only one p-value was less than .05. Even
 if the data tables showed differences than the control, the heat variable was the only
 variable that caused a difference according to the T‐Tests. With a p- value of .0076,
 the heat lamp was able to reject the null hypothesis and in turn support the
 alternate hypothesis stated at the beginning of the experiment. Even if the values of
 .0798 (Wind) and .0528 (Light) were different than the control, the p‐values failed
 to reject their respective null hypothesis and therefore show no tangible difference.
 As a result, our original hypothesis was supported and heat was able to increase the
 rate of transpiration. Light and Wind failed to show a difference in the rates of their
 respective plants.
 CONT………

19. DISCUSSIONANDCONCLUSION :-
 The experiment was valid and was run with multiple trials. There
were some
 discrepancies that could have altered the experiment. The wind
fan was turned off
 for a decent amount of time and could have changed the values
in the wind variable
 plant. Other small items such as the consistency of the bags tied
around each plant
 could also result in alterations. The experiment could be run for
more trials and
 have these problems fixed. Nevertheless, the experiment was
able to yield reliable
 results.
 Transpiration controls the rate of water absorption. It helps in the
absorption of minerals and regulate the temperature. At the
same time, it has disadvantages such as it leads water
deficiency in plants and thus, impair the process of
photosynthesis and growth etc. it is therefore said ‘transpiration
is a necessary evil’.