APPROVAL SHEET

The complete report of practicum plant physiology with title “Measurment

of water potential in Plant tissue”, created by:

Name : Nur Fahmi Utami

ID : 101 404 155

Class : Biology Bilingual

Group : V

it has been checked and consulted to Assistant/ Assistant Coordinator shall be

accepted.

Makassar, Mei 2nd 2012

Assistant Coordinator, Assistant,

Risna Irawati , S.Pd Yusmar Yusuf NIM . 081404172

Known by,Lecturer of Responsibility

Drs. Ismail, M.S NIP . 196112311986031015

CHAPTER IINTRODUCTION

A. Background Plants will develop normally and thrives as well as active when the

cells filled with water. At one point in time when development, water supply

shortages plant, the water content in plants decreased and the rate of

development is determined by the rate of all the functions is it’s also

declining. If the situation is prolonged drought could be killed the plants.

The simple and appealing explanation for osmosis is the concentration

of water explanation--water in pure water is simply more concentrated than

water in solutions because the solute has to take up some room in the

solution. According to this idea, water diffuses into a hyper osmotic solution

because it is diffusing down its concentration gradient. Apart from gradients

in potential required for water entry, the water potential of the tissue may also

affect growth rates directly because of the role of turgor in cell enlargement.

The behavior of tissue varies considerably in this regard. At one end of the

range, growth rate may be inversely proportional to the water potential of the

tissue, becoming zero at the water potential which corresponds approximately

to zero turgor.

Osmosis process also Occurs in living cells in nature. Changes in cell

shape occur if there is on a different solution. Cell located in an isotonic

solution, the volume will be constant. In this case, the cell will receive the

same and lose water. The last experiment, we measured the water potential of

plant tissues with high levels of salt (NaCl) is different. In this lab we will use

the Chardakov and Gravimetric techniques to determine the water potential

(Ψ w) of a potato tuber cells. We will determine the solute potential (Ψs) by the

Freezing Point Depression Method. We will determine the solute potential

(Ψs) by the Freezing Point Depression Method. Pressure in the cells can be

arithmetically calculated once Ψ s and Ψ w are known. Pressure in the cells

can be arithmetically calculated once Ψ s and Ψ w are known.

B. The PurposeTo measure of water potential value on potato tuber tissue.

C. The Benefit

Students University can be more understand about how to measure the water

potential value, especially in Solanum tuberosum.

CHAPTER IIPREVIEW OF LITERATURE

Osmosis is the diffusion of water across a semi permeable membrane

from an area where more water to areas with less water. Osmosis is determined by

the chemical potential of water or water potential, which describes the ability of

water molecules to be able to perform diffusion. A large volume of water will

have excess free energy than the little volume, under the same conditions. A free

energy per unit amount of substance, especially per gram molecular weight (mol

of free energy-1) is called chemical potential. Solute chemical potential

approximately proportional to the concentration of the solute. The diffusing solute

tends to move from areas of higher chemical potential to regions of lower

chemical potential (Sasmitamihardja, 1996).

The absolute value of water potential is not easily measured, but the

difference can be measured. As a handle or the base potential of pure water. So

the water potential is the difference in free energy or chemical potential per unit

molar volume of pure water and a solution at the same temperature. Ppotential of

pure water at atmospheric pressure is zero, and the water potential in the cell and

the solution was less than zero or negative (Ismail, 2012).

Water potential is an expression of free energy status of water, a measure

of power That Causes water to move into a system, Such as plant tissue, soil or

the atmosphere or from some other part that gets into one system. Water potential

is probably the most useful parameter to be measured in relation to the soil

system, plants and atmosphere (Ismail, 2009).

Osmotic potential is the potential Caused by the solutes. The sign is

always negative. Potential pressure is the pressure potential hydrostaticity caused

by cells in the cell wall. Its value is marked with numbers can be positive or

negative as well. Increase of pressure (pressure Turgid formation) resulted in

more positive pressure potential. Potential due to the bonding matrix of water in

colloidal protoplasm and surface (cell wall). Therefore, the above equation can be

simplified, tissue water potential is determined by immersing the tissue sections in

a series solution of sucrose or mannitol (non-electrolyte) which can be known

concentration (Ismail, 2009).

The entry of water into plant tissue is essential for cell enlargement.

Since water absorption occurs along graldients of decreasing water potential, the

water potential of growing plant tissue must be below that of the water supply.

The steepness of the gradient should depend to the resistance of the tissue to water

flow. Efforts to estimate gradients in potential of growing plant tissue have taken

2 main approaches. First, the water potential of the tissue and environment have

been deternmined by transferring the growing tissue to media containing solutes

and letermining the potential of the solution. however, in addition to problems

associated with the penetration of solutes inito the tissue, the interpretation of

these experiments is made difficult by the need to use reversible chainges in size

to identify tissue water potentials while the plant material is growing irreversibly.

In the second approach, measurements of the resistance to water entry have been

made by noting the half-time for equilibration of tissue segments in deuterated

water or in soltutions of various Concentrations (Boyer, 1968)

According to Anonymous (2012), as osmosis is a type of diffusion the

same things that affect diffusion have an effect on osmosis some of these things

are:

The concentration gradient - the more the difference in molecules on one side

of the membrane compared to the other, the greater the number of molecules

passing through the membrane and therefore the faster the rate of diffusion.

The surface area - the larger the area the quicker the rate of diffusion

The size of the diffusing particles - the smaller the particle the quicker the

rate and polar molecules diffuse faster than non-polar ones.

The temperature - the higher the temperature the more kinetic energy the

particles have and so the faster they move.

CHAPTER IIIPRACTICUM METHOD

A. Date and Place

Day/Date : Thursday, April 11th 2012

Time : At 10.50 – 13.00 pm

Place : Biology Laboratory of right side in 3rd floor at FMIPA UNM

B. Tools and Materials1. Tool

a. Drill 0.6 to 0.8 cm diameter cork 1 piece

b. 3 pieces of razor blade

c. 8 pieces of filter paper

d. Stopwatch 1 piece

e. Analytic scales of 1 pc

f. Petri dish 8 pieces

g. Tweezers

2. Materials

a. Potato tubers (Solanum tuberosum)

b. Distilled water

c. Sucrose solution of 0.1 M - 0.8 M

C. Work Procedure

1. Prepared 10 pieces of Petri dishes, each filled with 10 ml of solution like

that: distilled water, a solution of 0.1 M sucrose, 0.2 M, 0.3 M, 0.4 M, 0.5

M, 0.6 M, 0.7 M, and 0.8 M.

2. Performed the following steps quickly, making 10 in potato cylinders

with a diameter of 0.8 cm, each with a length of 4 cm, remove the skin.

Should all cylinders in potato tubers from the tuber only. Put the cylinder

in a closed container.

3. Used a razor blade, cut a potato cylinder into thin slices with a thickness

of 1-2 mm.

4. Rinsed the thin slices of potato with distilled water quickly, dry with

filter paper and weighed. Subsequently enter into a sucrose solution that

had been prepared. Do this on each cylinder of each potato to the next

solution.

5. Cylinder soak for 1 hour, remove the slices from each Petri dish, then dry

with a paper suction and weighed. Do this for all instances of the

experiment

6. The following formula to calculate the weight change, use the following

formula:

%Weight change= the final weight−the first weigtthe first weight

×100 %

7. Then made a chart and Plot percent weight change on the ordinate and

the concentration of sucrose solution (in molar) on the abscissa.

8. Tissue water potential can be obtained after first calculating osmotic

potential for each concentration of sucrose solution. Used the following

formula:

-Ψs = MIRT

Where M = molarities of sucrose solution

I = ionization constant, for sucrose = 1

R = gas constant () 0.0831 bar / degree mol

T = absolute temperature = (C + 273)

The formula above is used to calculate the osmotic potential of sucrose

solution temperature.

9. Then determined with polarize of the graph, the concentration of sucrose

which does not produce weight change. And calculate ψs of this solution.

Ψs value is proportional to water potential (ψw) tissue.

CHAPTER IVOBSERVATION RESULT AND DISCUSSION

A. Observation Result

Data analysis

%Weig h t c h ange=t he final weig ht−t he first weigtt h e first weig h t

× 100 %

Weight change = final weight - initial weight

1. Sucrose solution with concentration of 1,4

The first weight = 4,50 grams

The final weight = 4,50 grams

Weight change = 0 grams

Percent weight change = 0 %

2. Sucrose solution with concentration of 1,6

The first weight = 4,40 grams

The final weight = 4,50 grams

Weight change = 0.90 grams

Percent weight change = 25 %

3. Sucrose solution with concentration of 1,8

The first weight = 4,35 grams

The final weight = 4,50 grams

Consentration of Sucrosa

solution(M)

The first weight

(gr)

The final weight

(gr)

The change of weight

(gr)

Percentation of weight

(%)

1,4 4,50 4,50 0 01,6 4,40 5,50 1,10 251,8 4,35 4,50 0,25 0.572 4,30 5,00 1,30 30,2

2.2 4,45 3,50 -0,95 21,32,4 4,40 3,50 -0,90 20,42.6 4,00 4,50 0,50 12,52,8 4,35 4,00 -0,35 0,80

Weight change = 0,25 grams

Percent weight change = 0,57 %

4. Sucrose solution with concentration of 2

The first weight = 4,30 grams

The final weight = 5 grams

Weight change = 1,30 grams

Percent weight change = 30,2 %

5. Sucrose solution with concentration of 2,2

The first weight = 4,45 grams

The final weight = 3,50 grams

Weight change = -0, 95grams

Percent weight change = 21,3 %

6. Sucrose solution with concentration of 2,4

The first weight = 4,40 grams

The final weight = 3,50 grams

Weight change = -1,90 grams

Percent weight change = 20,4 %

7. Sucrose solution with concentration of 2,6

The first weight = 4 grams

The final weight = 4,50 grams

Weight change = 0,50 grams

Percent weight change = 12,5 %

8. Sucrose solution with concentration of 2,8

The first weight = 4,35 grams

The final weight = 4 grams

Weight change = -0,35 grams

Percent weight change = 0,80 %

1,4 1,6 1,8 2 2.2 2,4 2.6 2,8

-1.5

-1

-0.5

0

0.5

1

1.5

The change of weight (gr)

The change of weight (gr)

B. DiscussionSeen from the table, a solution of sucrose concentration each 1.4, 1.6,

1.8, 2, 2.2, 2.4, 2.6, and 2.8 M affects the absorption of water on the potato

that causes weight changes in potato and percentage changes. All potato its

weight changes are positive except potatoes with sucrose concentration 2.2,

2.4, and 2.8 M which is negative. Positive value is obtained from the final

weight of potatoes is greater than the first weight of potatoes, due to the

weight of the water tissue by sucrose solution.

1,4 1,6 1,8 2 2.2 2,4 2.6 2,80

1

2

3

4

5

6

The graph of weight potatoes (gr)

The first weight (gr)The final weight (gr)

Movement of water from a solution of sucrose to the potato cells

showed with the concentration of water in the solution of sucrose higher than

in the potato cells. Thus the solution sucrose 1.4, 1.6, 1.8, 2, and 2.8 M called

hypotonic solution (a solution with content solute is lower than other

solutions). Negative values and % change in weight changes that occur in the

final sucrose concentration of 2.2, 2.4, and 2.8 M is obtained from the final

weight of potatoes that are smaller than its first weight, due to severe tissue

shrinkage occurs because the water out of cells into a solution of sucrose so

that it can be concluded that the solution is hypertonic (its solute content

higher than the surrounding). And if they occur in plants are still actively

growing, the plants may experience stress due to disruption of the water

absorption process. This happens because the number of solutes in the cell or

tissue of the plant will increase the value of the osmotic potential of the plant

itself and the lower the water potential value.

At this practical, there is no potato tissues that do not have additional

expenses or water or no movement of water molecules because there is no

concentration gradient solution having a concentration equal to the

concentration of the solution in the cell called the isotonic solution.

From the observations, all the potatoes with different concentrations

experienced additional weight except potato tubers with sucrose solution of

2.2 M, 2.4 M, and 2.8 M experienced of weight decrease after immersion and

drying.

The reduction of the first weight of potato tubers caused by water

potential in potato tubers is higher than the water potential in the sucrose

solution, so water moves out of place in the potato. Based on the theory that

water moves from higher water potential to lower water potential.

Displacement or movement of water molecules from the high water potential

to low water potential called osmosis (Anonymous, 2012).

CHAPTER VCONCLUSION AND SUGGESTION

A. Conclusion

1. Water potential is the ability of water to perform the movement or

displacement, water passes from the solution with higher water potential

to a solution with a lower water potential.

2. additional of water potential of the cell or plant tissue due to lower

osmotic potential, whereas the decrease in water potential of plant cells

or tissue due to increased osmotic potential, the process of that happening

are caused or influenced by solutes that exist in the cell or plant tissue.

3. The concentration sucrose of 2.2 M, 2.4 M and 2.8 M its solution is

hypertonic while the other concentration sucrose is hypotonic

B. Suggestion

1. Suggestion for the laboratory;

The laboratory staff should be paid attention is material that

uncompleted.

2. Suggestions for assistant.

Assistant should be gave more again information about observation

3. Suggestion for friend.

The student hope able works well and carefully in this practicum so the

picture result better.

BIBLIOGRAPHY

Anonymous. 2012. To determine the water potential, (Online),

http://www.coursework.info/GCSE/Biology/Life_Processes___Cells/_

To_determine_the_water_potential_of_a_p_L78204.html, access April

17th 2012.

Boyer, Jhon S. 1968. Relationship of Water Potential to Growth of

Leaves',Department of Botany, University of Illinois. Urbana, Illinois

61801 (Received January 25, 1968) (Online,access April 17th 2012.

Ismail. 2009. Fisiologi Tumbuhan. Makassar: Jurusan Biologi FMIPA UNM.

Ismail & Abd. Muis. 2012. Penuntun Praktikum Fisiologi Tumbuhan. Makassar:

Laboratorium Biologi. FMIPA UNM.

Sasmitamihardja, dradjat. 1996. Fisiologi tumbuhan. Bandung : FMIPA ITB.